A plurality of p anode regions are formed at one surface of an nxe2x88x92 substrate. A trench is formed in each p anode region. An ohmic junction region is formed between an anode metallic electrode and the p anode region. The p anode region has a minimum impurity concentration at a portion near the ohmic junction region which enables ohmic contact. A cathode metallic electrode is formed at the other surface of the nxe2x88x92 substrate with an n+ cathode region interposed. Accordingly, a semiconductor device which has an improved withstand voltage and in which the reverse recovery current is reduced can be obtained.

1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing a semiconductor device. The invention particularly relates to a semiconductor device which has a higher withstand voltage and in which the reverse recovery current is reduced, and a method of manufacturing such a semiconductor device.
2. Description of the Background Art
A semiconductor device such as an IGBT (Insulated Gate Bipolar Transistor) is applied to various inverter circuits as a switching element. In order to release the energy stored in an inductive load in the switching process and utilize it as the circulating current, a diode is connected in antiparallel with a main semiconductor device. Such a diode is especially referred to as a flywheel diode.
Excess carriers are stored in a diode in the forward bias state, that is, in the ON state. The stored excess carriers are released in the process of transition to the OFF state, that is, the reverse bias state. At this time, current flows in a direction opposite to the forward direction of the diode. This current is especially referred to as reverse recovery current which flows into a semiconductor device such as the IGBT, resulting in the loss. The excess carriers which constitute the reverse recovery current are, in this case, minority carriers or holes.
A diode in which the minority carriers are not stored is the Schottky diode. Description of the Schottky diode is given below referring to the figure. With reference to FIG. 54, at one surface of an nxe2x88x92 substrate 101, a silicon oxide film 107 is formed. An anode metallic electrode 105 is further formed via a Schottky junction region 104. At the other surface of nxe2x88x92 substrate 101, a cathode metallic electrode 106 is formed via an n+ cathode region 102.
In this structure, most current flowing through Schottky junction region 104 is constituted by the majority carriers. Therefore, no minority carrier is stored in nxe2x88x92 substrate 101, and the reverse recovery current is small. As a result, a high speed switching is possible. However, the withstand voltage in the reverse bias state depends on Schottky junction region 104. The withstand voltage is about 100V at most, and improvement of the withstand voltage is impossible.
In order to improve the withstand voltage, a structure has been used in which a pn junction is provided around the Schottky junction region, a depletion layer extending from the pn junction in the reverse bias state is utilized, and the withstand voltage is obtained. A first conventional diode having such a structure is described referring to the figure. With reference to FIG. 55, a plurality of p anode regions 103 are formed at one surface of nxe2x88x92 substrate 101. On the one surface of nxe2x88x92 substrate 101 including p anode regions 103, an anode metallic electrode 105 is formed. Schottky junction region 104 is formed between anode metallic electrode 105 and n substrate 101. On the other surface of nxe2x88x92 substrate 101, a cathode metallic electrode 106 is formed via n+ cathode region 102.
In this diode, a depletion layer extends from an interface between p anode regions 103 and nxe2x88x92 substrate 101 toward the nxe2x88x92 substrate particularly in the reverse bias state. In the vicinity of Schottky junction region 104, the depletion layers extending from the interfaces between the adjacent p anode regions 103 and nxe2x88x92 substrate 101 connect with each other, easing the electric field. As a result, the withstand voltage in the reverse bias state is improved compared with the Schottky diode.
A second conventional diode is described referring to the figure. With reference to FIG. 56, a plurality of p anode regions 103 are formed at one surface of nxe2x88x92 substrate 101. At regions between respective p anode regions 103, a pxe2x88x92 region 108 is formed. On p anode regions 103 and pxe2x88x92 region 108, anode metallic electrode 105 is provided. On the other surface of the nxe2x88x92 substrate, cathode metallic electrode 106 is formed via n+ cathode region 102.
In this diode, a depletion layer extends from an interface between p anode region 103 and nxe2x88x92 substrate 101 toward nxe2x88x92 substrate 101, and a depletion layer further extends from an interface between pxe2x88x92 region 108 and nxe2x88x92 substrate 101 toward nxe2x88x92 substrate 101, particularly in the reverse bias state. As a result, the withstand voltage is further improved compared with the diode shown in FIG. 55.
A third conventional diode disclosed in Japanese Patent Laying-Open No. 4-321274 is described referring to the figure. With reference to FIG. 57, a plurality of concave portions 206 are formed at one surface of a semiconductor substrate of one conductivity type 201. A semiconductor region of opposite conductivity type 204 is formed along an inner surface of each concave portion 206. A one electrode metal 205 is formed on one conductivity type semiconductor substrate 201 including the surface of concave portion 206. On the opposite side of one conductivity type semiconductor substrate 201, an ohmic electrode metal 203 is formed via a one conductivity type semiconductor 202 of low resistance. One conductivity type semiconductor substrate 201 and one electrode metal 205 constitute the Schottky barrier junction.
In this diode, a depletion layer extends from an interface between semiconductor region of opposite conductivity type 204 and semiconductor substrate of one conductivity type 201 toward one conductivity type semiconductor substrate 201 in the reverse bias state. At this time, the portion adjacent to the interface between one conductivity type semiconductor substrate 201 and one electrode metal 205 is sandwiched between the depletion layers. Accordingly, in a portion adjacent to one conductivity type semiconductor substrate 201 and one electrode metal 205, the electric field is eased and the withstand voltage is improved.
Next a fourth conventional diode disclosed in U.S. Pat. No. 4,982,260 is described. Referring to FIG. 58, on one surface of a first semiconductor substrate layer 502, a second semiconductor layer 506 is formed. At a main surface 508 of the second semiconductor layer 506, a plurality of trenches 512A-12F are formed. P+ regions 510A-10D as well as mesa regions 514A-14C are alternately provided between adjacent trenches. The depth of p+ regions 510A-10D is substantially identical to that of trenches 512A-12F. Oxide layers 522A-22F are respectively formed at respective inner surfaces of trenches 512A-12F. A metallic anode 518 is formed on main surface 508 of the second semiconductor layer 506. Schottky barrier regions 550A-50C are formed between metallic anode 518 and the second semiconductor layer 506. A cathode 504 is formed on the other surface of the first semiconductor substrate layer 502.
In this diode, a depletion layer extends from an interface between p+ regions 510A-10D and the second semiconductor layer 506 toward the second semiconductor layer 506 in the reverse bias state. The depletion layer extending from each interface is connected with adjacent depletion layers, and the withstand voltage of the diode is improved.
Another diode disclosed in U.S. Pat. No. 4,982,260 is described as a fifth conventional art using the figure. With reference to FIG. 59, on one surface of a first semiconductor substrate layer 702, a second semiconductor layer 706 is formed. A plurality of trenches 710A-710F are provided at a main surface of second semiconductor layer 706. At the bottoms of respective trenches 710A-710F, p+ regions 720A-720F are provided. Respective trenches 710A-710F have their side surfaces at which oxide layers 722A-722J are formed. On the main surface of the semiconductor layer 706, a metallic anode 716 is formed. On the other surface of the first semiconductor substrate layer 702, a cathode 704 is formed.
In this diode, a depletion layer extends from an interface between p+ regions 720A-720F and the second semiconductor layer 706 toward the second semiconductor layer 706. Each depletion layer is connected to adjacent depletion layers, and extends to still deeper region in the second semiconductor layer 706. As a result, the withstand voltage of the diode is further improved.
Problems of those conventional diodes described above are as follows.
In the diode shown in FIG. 55 presented as the first conventional art, holes as minority carriers are injected from p anode region 103 toward nxe2x88x92 substrate 101 in the forward bias state. At this time, p anode region 103 includes a relatively large number of impurities, so that still more holes are injected into nxe2x88x92 substrate 101 and stored therein. Therefore, the reverse recovery current increases in the process of transition from the forward bias state to the zero bias state.
In the diode shown in FIG. 56 presented as the second conventional art, p anode region 103 has a relatively high concentration, so that still more holes are injected from p anode region 103 into nxe2x88x92 substrate 101 in the forward bias state. As a result, the reverse recovery current increases.
When the potential between the metallic anode 716 and cathode 704 in the reverse bias state becomes higher, a depletion layer extends from an interface between pxe2x88x92 region 108 and nxe2x88x92 substrate 101 toward nxe2x88x92 substrate 101, and the depletion layer further extends toward pxe2x88x92 region 108. If the edge of the depletion layer has contact with anode metallic electrode 105, the dielectric breakdown could occur.
In the diode shown in FIG. 57 as the third conventional art, after concave portion 206 is formed at one conductivity type semiconductor substrate 201, opposite conductivity type semiconductor region 204 is formed along the inner surface of concave portion 206. Therefore, the concentration of impurities is relatively high in the entire semiconductor region of opposite conductivity type 204. As a result, still more holes are injected from opposite conductivity type semiconductor region 204 into one conductivity type semiconductor substrate 201 in the forward bias state. As a result, the reverse recovery current increases.
In the diode shown in FIG. 58 as the fourth conventional art, the concentration of impurities in the formed p+ regions 510A-10D is relatively high. Still more holes are injected from the p+ regions into the second semiconductor layer in the forward bias state. As a result, the reverse recovery current increases.
In the diode shown in FIG. 59 as the fifth conventional art, the concentration of impurities in the formed p+ regions 720A-720F is relatively high, and the reverse recovery current also increases.
The invention is made to solve the problems above. One object of the present invention is to provide a semiconductor device which has an improved withstand voltage and in which the reverse recovery current is reduced. Another object of the present invention is to provide a method of manufacturing such a semiconductor device.
A semiconductor device according to a first aspect of the invention includes a semiconductor substrate of a first conductivity type, a plurality of trench portions, a plurality of impurity regions of a second conductivity type, and a first electrode layer. The plurality of trench portions are selectively formed at a first main surface of the semiconductor substrate. The plurality of impurity regions of the second conductivity type are in contact with at least bottom surfaces of respective trench portions and are formed deeper than respective trench portions. The first electrode layer is formed on the first main surface of the semiconductor substrate. The first electrode layer and a region of the first conductivity type of the semiconductor substrate constitute a Schottky junction at the first main surface. The first electrode layer is in ohmic contact with the impurity region at a prescribed junction surface. Each impurity region has a minimum impurity concentration which enables the ohmic contact with the first electrode layer at a portion near the prescribed junction surface, and has an impurity concentration still lower than the minimum impurity concentration which enables the ohmic contact at a portion other than the portion near the prescribed junction surface.
In this structure, minority carriers are injected from the impurity region in ohmic contact with the first electrode layer into the semiconductor substrate in the forward bias state in which one prescribed potential is applied to the first electrode layer and the semiconductor substrate respectively. An amount of injected minority carriers depends on an impurity concentration in the impurity region. In this case, the impurity region has a minimum impurity concentration which enables the ohmic contact with the first electrode layer at a portion adjacent to a prescribed junction surface, and has an impurity concentration still lower than the minimum impurity region at the other portion. Accordingly, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein is reduced. As a result, the reverse recovery current flowing into the semiconductor device in a reverse bias direction in the process of transition from the forward bias state to the reverse bias state.
A depletion layer extends from an interface between the impurity region and the semiconductor substrate toward the semiconductor substrate in the reverse bias state in which another prescribed potential is applied to the first electrode layer and the semiconductor substrate respectively. At this time, at a region adjacent to the Schottky junction, the electric field is eased since depletion layers extending from adjacent impurity regions are connected with each other. The depletion layer extends deeper in the semiconductor substrate since each impurity region is formed deeper than the trench portion. Therefore, the distance from the first electrode layer to the edge of the depletion layer increases. The withstand voltage of a semiconductor substrate in the reverse bias state is thus improved.
Preferably, each impurity region is formed to be in contact with both sides of the trench portion as well as the first main surface in the vicinity of the both sides. A prescribed junction surface is located at, at least the first main surface of the impurity region.
In this case, each impurity region has a trench portion formed therein, so that the impurity region is substantially located at a portion near the junction with the semiconductor substrate. An impurity concentration of the impurity region formed at the semiconductor substrate gradually decreases from the portion near the center of the first main surface of the impurity region to an interface between the impurity region and the semiconductor substrate. A portion having a relatively high impurity concentration is removed by forming the trench portion in the impurity region. An impurity concentration of a portion remaining substantially as an impurity region is relatively low. Therefore, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein in the forward bias state is further reduced. As a result, the reverse recovery current is further reduced.
Preferably, insulator is embedded in each trench portion.
In this case, the first electrode layer is in ohmic contact with the impurity region only at the first main surface. The area of the ohmic contact between the first electrode layer and the impurity region is reduced. An amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein in the forward bias state is further reduced. As a result, further reduction of the reverse recovery current is achieved.
Still preferably, an insulating layer formed at surfaces of both sides of the trench portion is included. Each impurity region is formed to be in contact with only a portion near a bottom surface of each trench portion, and a prescribed junction surface is located at a bottom surface of each trench portion.
In this case, the impurity region is formed within the semiconductor substrate to be in contact with only a portion near the bottom surface of the trench portion. In other words, the impurity region is formed at a position distant from the first main surface of the semiconductor substrate. A depletion layer extends from an interface between the impurity region and the semiconductor substrate toward the semiconductor substrate to a still deeper position in the reverse bias state. The electric field of a portion near the Schottky junction is further eased. As a result, the withstand voltage of the semiconductor device in the reverse bias state is improved.
A semiconductor device according to the second aspect of the invention includes a semiconductor substrate of a first conductivity type, a plurality of trench portions, a conductor, an impurity region of a second conductivity type, and a first electrode layer. The plurality of trench portions are selectively formed at a first main surface of the semiconductor substrate. The conductor is embedded in each trench portion with a first insulating layer therebetween. The impurity region of the second conductivity type is formed at a region between respective trench portions of the first main surface of the semiconductor substrate, in contact with at least one of the opposite sides of adjacent trench portions, and has a depth deeper than that of the trench portion. The first electrode layer is formed on the first main surface of the semiconductor substrate. The first electrode layer is in ohmic contact with each impurity region at the first main surface. Each impurity region has a minimum impurity concentration which enables ohmic contact with the first electrode layer at a portion near the first main surface, and has an impurity concentration still lower than the minimum impurity region which enables ohmic contact, at a portion other than that near the first main surface.
In this structure, minority carriers are injected from the impurity region in ohmic contact with the first electrode layer into the semiconductor substrate in the forward bias state in which one prescribed potential is applied to the first electrode layer and the semiconductor substrate respectively. An amount of injected minority carriers depends on an impurity concentration of the impurity region. In this case, the impurity region has the minimum impurity concentration which enables ohmic contact with the first electrode layer at the first main surface, and has an impurity concentration still lower than the minimum impurity concentration at the other portion. Accordingly, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein is reduced. As a result, the reverse recovery current flowing into the semiconductor device in the reverse bias direction in the transition from the forward bias state to the reverse bias state is reduced.
A depletion layer extends from an interface between the impurity region and the semiconductor substrate toward the semiconductor substrate in the reverse bias state in which the other prescribed potential is applied to the first electrode layer and the semiconductor substrate respectively. Since the impurity region has its depth larger than that of the trench portion, the depletion layer further extends toward the first main surface at a portion near the region in which the interface and the side of the trench portion are in contact with each other. Accordingly, the depletion layer further extends at a portion adjacent to both sides of the trench portion, and the withstand voltage of the semiconductor device in the reverse bias state is improved.
Preferably, the impurity region is formed to be in contact with the opposite sides of adjacent trench portions, and the first electrode layer and a region of the first conductivity type of the semiconductor substrate form the Schottky junction at the first main surface.
In this case, a region in which the impurity region is formed is reduced. An amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein in the forward bias state is further reduced. As a result, the reverse recovery current flowing in the semiconductor device in the reverse bias direction in transition from the forward bias state to the reverse bias state is reduced.
Preferably, each impurity region is formed at both sides of each trench portion to be in contact with one side of each trench portion. The first electrode layer and a region of the first conductivity type of the semiconductor substrate form the Schottky junction at the first main surface.
In this case, an impurity region formed to be in contact with the side of each trench portion is located in a region sandwiched between respective trench portions. The first conductivity type region of the semiconductor substrate sandwiched between impurity regions and the first electrode layer form the Schottky junction. Therefore, a region in which the impurity region is formed is further reduced. As a result, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein in the forward bias state is further reduced.
A depletion layer extends from an interface between the impurity region located between respective trench portions and the semiconductor substrate toward the semiconductor substrate in the reverse bias state. A depletion layer extending from the portion between respective trench portions is easily connected with an adjacent depletion layer. As a result, the reverse recovery current flowing in the semiconductor device in the reverse bias direction in the transition from the forward bias state to the reverse bias state is reduced. Further, the withstand voltage of the semiconductor device in the reverse bias state is improved.
Preferably, a second insulating layer formed on each conductor which insulates the first electrode layer from each conductor, and an electrode portion electrically connected with each conductor are included.
In this case, voltage of at least a prescribed threshold voltage is applied to the electrode portion. At this time, the conductivity type of the impurity region near the second insulating layer of each trench portion is reversed and a channel region is formed. At the same time that minority carriers are injected from the impurity region toward the semiconductor substrate, carriers of a conductivity type opposite to that of the minority carriers reach the first electrode layer through the channel region. The carriers of the opposite conductivity type which reach the first electrode layer again couple with the minority carriers in the impurity region and disappear. Accordingly, an amount of the minority carriers injected from the impurity region into the semiconductor substrate and stored therein is reduced. Reduction of the reverse recovery current flowing in the semiconductor device in the reverse bias direction in transition from the forward bias state to the reverse bias state is achieved.
Voltage of a prescribed threshold voltage or less is applied in the reverse bias state. The absolute value of the voltage is approximately equivalent to that of the voltage applied in the forward bias state. At this time, a depletion layer extends from an interface between the second insulating layer of each trench portion and the semiconductor substrate toward the semiconductor substrate. A depletion layer further extends from an interface between the impurity region and the semiconductor substrate toward the semiconductor substrate. These depletion layers easily connect with adjacent depletion layers. As a result, the withstand voltage of the semiconductor device in the reverse bias state is improved.
Preferably, the impurity region is formed to be in contact with the opposite sides of adjacent trench portions, and includes a second insulating layer formed on each conductor and insulates the first electrode layer from each conductor, and includes an electrode portion electrically connected with each conductor.
In this case, the impurity region is formed at a region between respective trench portions. In the forward bias state, voltage of at least a prescribed threshold voltage is applied to the electrode portion. At this time, the conductivity type of the impurity region near the second insulating layer of each trench portion is reversed and a channel region is formed. At the same time that minority carriers are injected from the impurity region toward the semiconductor substrate, carriers of a conductivity type opposite to that of the minority carriers reach the first electrode layer again through the channel region. Carriers of the opposite conductivity type which reach the first electrode layer again couple with minority carriers in the impurity region and disappear. As a result, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein is reduced.
Voltage of a prescribed threshold voltage or less is applied in the reverse bias state. At this time, in addition to a depletion layer extending from an interface between the impurity region and the semiconductor substrate toward the semiconductor substrate, a depletion layer extends from an interface between the second insulating layer of each trench portion and the semiconductor substrate toward the semiconductor substrate. As a result, reduction of the reverse recovery current flowing in the semiconductor device in the reverse direction in transition from the forward bias state to the reverse bias state, as well as improvement of the withstand voltage of the semiconductor device in the reverse bias state are achieved.
Preferably, the first electrode layer is formed of aluminum, and the minimum impurity concentration which enables ohmic contact with the first electrode layer is 1xc3x971016xe2x88x921xc3x971017/cm3.
In this case, ohmic contact can be formed easily as desired.
A method of manufacturing a semiconductor device according to the third aspect of the invention includes following steps. Into a first main surface of a semiconductor substrate of a first conductivity type, impurities of a second conductivity type are selectively introduced. A plurality of impurity regions are formed by heat treatment. A Schottky junction portion is formed at the first main surface of a region of the first conductivity type of the semiconductor substrate. A trench portion is formed in each impurity region by the anisotropic etching. A first electrode layer is formed on the first main surface of the semiconductor substrate such that it is in ohmic contact with the impurity region at, at least the first main surface.
This manufacturing method allows an impurity concentration of the impurity region formed at the semiconductor substrate to be gradually reduced from the portion near the center of the semiconductor substrate of the first main surface toward the interface with the semiconductor substrate. By forming the trench portion at the impurity region, a region having a relatively high impurity concentration is removed from the impurity region. Therefore, an impurity region actually formed corresponds to a portion having a relatively low impurity concentration located at a portion near the interface with the semiconductor substrate. The impurity region is in ohmic contact with the first electrode layer at, at least the first main surface. An amount of minority carriers injected from the impurity region into the semiconductor substrate in the forward bias state is thus reduced. A semiconductor device in which the reverse recovery current flowing in the reverse bias direction in transition from the forward bias state to the zero bias state is reduced can be obtained.
The method further includes a step of embedding an insulator in each trench portion.
In this case, the first electrode layer is in ohmic contact with the impurity region only at the first main surface. Accordingly, an area of a portion in which the first electrode layer and the impurity region are in ohmic contact with each other is reduced. Further, an amount of minority carriers injected from the impurity region into the semiconductor substrate and stored therein in the forward bias state is reduced. As a result, a semiconductor device in which the reverse recovery current is further reduced can be obtained.
Preferably, aluminum is used for the first electrode layer, and the impurity region is formed such that it has an impurity concentration of 1xc3x971016xe2x88x921xc3x971017/cm3at a portion near the junction surface with the first electrode layer.
In this case, the impurity region is formed to have a minimum impurity concentration which enables ohmic contact with the first electrode layer.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

Semiconductor device and method of manufacturing thereof


A dental curing light including an elongate wand having a proximal end and a distal end, a plurality of LEDs disposed at or near a distal end of the elongate wand and a printed circuit board for mounting the plurality of LEDs. The LEDs include a main through mount LED and a plurality of surface mount LEDs positioned around the main through mount LED. The main LED is through mounted relative to the printed circuit board such that the power connections of the main through mount LED are made through a hole or holes in the printed circuit board. The power connections of the main through mount LED are made on an opposite surface of the printed circuit board relative to the “top” surface to which the surface mount LEDs are mounted.

1. The Field of the Invention
The present invention generally relates to the field of light curing devices and, more specifically, to light curing devices incorporating light emitting diodes (LEDs).
2. The Relevant Technology
In the field of dentistry, dental cavities are often filled and/or sealed with photosensitive compounds that are cured by exposure to radiant energy, such as visible light. These compounds, commonly referred to as light-curable compounds, are placed within dental cavity preparations or onto dental surfaces where they are subsequently irradiated by light. The radiated light causes photosensitive components within the compounds to polymerize, thereby hardening the light-curable compounds within the dental cavity preparation or another desired location.
Existing light-curing devices are typically configured with a light source, such as a quartz-tungsten-halogen (QTH) bulb or an LED light source. QTH bulbs are particularly useful because they are configured to generate a broad spectrum of light that can be used to cure a broad range of products. In particular, a QTH bulb is typically configured to emit a continuous spectrum of light in a preferred range of about 350 nm to about 500 nm. Some QTH bulbs may even emit a broader spectrum of light, although filters are typically used to limit the range of emitted light to the preferred range mentioned above.
One reason it is useful for the QTH bulb to emit a broad spectrum of light is because many dental compounds cure at different wavelengths. For example, camphorquinone is a common photo-initiator that is most responsive to light having a wavelength of about 460 nm to about 470 nm. Other light-curable products, however, including many adhesives are cured when they are irradiated by light wavelengths in the 350 nm to 400 nm range. Accordingly, QTH bulbs can be used to cure both camphorquinone initiated products as well as adhesives.
One problem with QTH bulbs, however, is that they generate a relatively high quantity of heat, making it impractical to place QTH bulbs on the portions of the light-curing devices that are inserted within the mouth of a patient. In particular, if the QTH bulbs were disposed at the tips of the light-curing devices, the heat generated by the QTH bulbs could burn or agitate the sensitive mouth tissues of the patient. Accordingly, the QTH bulbs are typically disposed remotely from the portion of the light-curing device that is inserted within a patient's mouth. The heat generated by QTH bulbs also represents wasted energy, which increases the power requirement to achieve a desired light intensity.
To channel and direct the light emitted by a QTH bulb to the desired location within a patient's mouth, existing curing lights must utilize light guides, such as fiber optic wands and tubular light guides, or special reflectors. Although fiber optic wands and reflectors are useful for their intended purposes, they are somewhat undesirable because they can add to the cost and weight of the equipment, thereby increasing the overall cost and difficulty of performing the light-curing dental procedures.
In an attempt to overcome the aforementioned problems, some light-generating devices have been manufactured using alternative light generating sources, such as light-emitting diodes (LEDs) which are generally configured to only radiate light at specific wavelengths, thereby eliminating the need for special filters and generally reducing the amount of input power required to generate a desired output of radiation.
LEDs are particularly suitable light sources because they generate much less heat than QTH bulbs, thereby enabling the LEDs to be placed at the tip of the curing lights and to be inserted directly within the patient's mouth. This is particularly useful for reducing or eliminating the need for light guides such as optical fiber wands.
One limitation of LEDs, however, is that they are only configured to emit a narrow spectrum of light. For example, a 460 nm LED or LED array will generally only emit light having a spectrum of 460 nm±30 nm. Accordingly, a light curing device utilizing a 460 nm LED light source will be well designed to cure camphorquinone initiated products, but will not be suitable for curing adhesives that are responsive to light in the 400 nm±30 nm range. Likewise, a light-curing device utilizing a 400 nm light source may be suitable to cure some adhesives, but will be unsuitable for curing camphorquinone initiated products.
In an attempt to overcome this limited utility, some light generating devices have been manufactured that include multiple LEDs configured to emit light at different wavelengths. However, because the different wavelengths of light are generated at different points (in contrast to a QTH bulb, or light redirected through a light guide, for example), it can be difficult to produce sufficient intensities of desired wavelengths across the full footprint of light emitted by the device. In other words, there are often "hot" and "cold" areas within the footprint of light generated with respect to any given wavelength.
In view of the foregoing, there exists a need to develop dental curing lights including multiple LEDs capable of providing more even intensities of any given wavelength across the full footprint of light emitted. It would be a further improvement to provide a dental curing light capable of better blending different wavelengths across the full footprint of light emitted in order to provide a broader spectrum of light across the full footprint.

Dental curing light with specially arranged LEDs


Methods, systems and components for use with or as a phase frequency detector. The phase frequency detector stretches its output pulse, allowing the detector to operate in a more linear region. As part of the invention, a new configuration for a D type flip flop is also disclosed. In one embodiment, the D type flip flop triggers at both the rising and the falling edges of the reference input, allowing a lower frequency input to be used while having the advantages of a higher frequency.

The recent revolution in telecommunications has led to a corresponding revolution in electronics. Wireless communications devices are now as plentiful as the rotary telephone of yesteryears. One key component of many wireless circuits is the delta sigma controlled fractional N frequency synthesizer. Such a circuit allows for the synthesizing of almost any required signal frequency. As part of this component, a phase frequency detector (PFD) receives an input reference signal with a known frequency and a variable input signal, known as a divider input, with a variable frequency determined by dividing a VCO (voltage controlled oscillator) frequency. The PFD outputs a signal that is proportional to the difference in phase between the input reference signal and the divider input. This output can then be used to increase-or decrease the VCO frequency to minimize the phase difference. This feedback arrangement is called a phase lock loop or a PLL.
Current PFD designs suffer from what is commonly termed a "deadzone". When the frequency synthesizer is in lock, the phase difference between the reference and the divider input is very close to zero. Thus, the output (or outputs as the PFD may have more than one output) should not be active or, if they are, the pulses produced should be very narrow. For small phase errors close to zero, due to delays and uncontrollable circumstances, it is not possible to create a complete pulse at the output of the PFD. This results in a flat or non-linear section in the PFD transfer curve normally termed a deadzone. While not very serious for integer-N synthesizers, this can result in increased fractional-N spur levels for delta sigma controlled fractional-N frequency synthesizers.
As such, there is therefore a need for systems and components which avoid the above problems. It is therefore an object of the present invention to mitigate if not overcome the shortcomings of the prior art.

Phase frequency detector with a novel D flip flop


Systems and methods for determining whether mechanical fatigue exists in a downhole cable using thermally-induced acoustic waves are disclosed herein. A cable fatigue monitoring system includes a thermal source, one or more light sources, one or more photodetector arrays, and a computing system comprising a processor, a memory, and a cable distortion module. The cable distortion module is operable to generate acoustic waves in a cable using the thermal source, direct light from the one or more light sources toward the cable, detect light from the one or more light sources transmitted past the cable at the one or more photodetector arrays, and determine, based on the detected light transmitted past the cable, whether a change in velocity of the acoustic waves has occurred in the cable.

The present disclosure relates generally to measuring mechanical fatigue in downhole loading cables and, more particularly, to determining mechanical fatigue in polymer composite material based wireline or slickline cables using thermally-induced acoustic waves.
Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations that may be located onshore or offshore. When performing operations for removing the hydrocarbons from the subterranean formations, it may be desirable to obtain information about the formation. One method of obtaining information about the formation is the use of a wellbore logging tool coupled to a wireline or slickline system, wherein the wellbore logging tool is lowered into the wellbore using a downhole loading cable. Mechanical fatigue of the polymer composite material based cable may occur over time due to structural defects in the cable (e.g., small cracks, delaminations, or voids) and may cause logging service failure during logging operations. Current nondestructive cable inspection methods (e.g., x-ray, microwave, or gamma-ray inspection methods) may require a direct measurement of a portion of the logging tool cable, and may therefore require the cable to be relatively stationary while the measurement is taken. However, the logging tool cable may be lowered into the well during logging operations at high velocities, making stationary methods of measuring mechanical fatigue on the cable impracticable. It is therefore desirable to provide a dynamic and nondestructive inspection method to identify potential cable failure events, onset of failure modes in the cable, and degradation trends in the cable's structural strength.
While embodiments of this disclosure have been depicted and described and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.

Wireline cable fatigue monitoring using thermally-induced acoustic waves


A liquid crystal display panel includes a first substrate, a second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, a color filter having a plurality of first color barriers, second color barriers, and third color barriers. A lower alignment layer is disposed on the first substrate having a plurality of first lower alignment units, second lower alignment units, and third lower alignment units corresponding to the plurality of first color barriers, second color barriers, and third color barriers, respectively. An upper alignment layer is disposed on the second substrate having a plurality of first upper alignment units, second upper alignment units, and third upper alignment units corresponding to the plurality of first color barriers, second color barriers, and third color barriers, respectively. A lower regionalized polarizer is disposed on the first substrate, and an upper regionalized polarizer is disposed on the second substrate.

Among various flat panel display devices, thin film transistor liquid crystal displays (TFT-LCD) dominate the mainstream flat penal display market due to their compact size, low power consumption, relatively low manufacturing cost, and zero radiation. A liquid crystal display device mainly includes a liquid crystal display panel and a back light module. The back light module is the light source that provides the light to illuminate the liquid crystal display panel. The light emitted out of the liquid crystal display panel is modulated by the liquid crystal display panel to display images.
The liquid crystal display panel includes a color filter. The light emitted from the back light module passes through the color filter and is mixed together to display various colors. Ideally, the displayed colors reproduce the natural colors as much as possible. Alternatively, the displayed colors are adjusted to approximate the desired colors to satisfy user's requirements and to adapt to the specific application environment of the liquid crystal display panel.
The white point adjustment is most important for quantitatively processing all natural colors. FIG. 1 illustrates a schematic view of a CIE-xy chromaticity diagram. Referring to FIG. 1, the diagram represents a given color in chromaticity hue and saturation position in the color base coordinate system. Specifically, the XYZ display system has the tristimulus values X, Y, and Z represented in the chromaticity coordinates as the horizontal axis x=X÷(X+Y+Z) and the vertical axis y=Y÷(X+Y+Z). All the colors that can be seen by human eyes are shown in the diagram as the inner portion of the horseshoe shape formed by the closed curve C. The R, G, and B points in the diagram represent the three primary colors, red, green, and blue respectively in a certain color display system. All the colors on the sides of the triangle RGB or inside the triangle RGB may be represented in a proper mixture of the three primary colors. In addition, the white color with the maximum brightness is represented at the point W where all three primary colors reach the maximum brightness. The white color W point is in the vicinity of the triangle RGB centroid.
When designing a color display system, an optimized and requirement satisfying white color point is obtained by adjusting the maximum brightness of the R, G, and B points. In the current technologies, the thicknesses of the red color barriers, green color barriers, and blue color barriers in the color filter are adjusted to optimize the white color point. For example, increasing the thickness of the green color barriers may decrease the light-transmittance of the green color barriers and thereby reduce the maximum brightness of the green light.
However, the method of matching the white color point by adjusting the thicknesses of the color barriers may have certain limitations. For example, after the thicknesses of the color barriers are determined, the brightness of the color barriers cannot be changed. When the color display system has additional special requirement for the white color point, further adjustment of the thicknesses of the color barriers to optimize the white color point may cause substantial differences in the thicknesses of the color barriers and thereby may affect the display effect.
Another drawback of the color barrier thickness adjustment method is that each white color point designed for a certain specification requires a matching color filter with fixed thicknesses of the color barriers. As a result, liquid crystal display panels with different product specifications may need different color filters. The inability of sharing a common color filter across different liquid crystal display panel products may increase the production cost.
The disclosed liquid crystal display panel and fabrication method are directed to solve one or more problems in the art.

Liquid crystal display panel and fabrication method thereof

XIAMEN TIANMA MICRO-ELECTRONICS CO., LTD.


An electrical connector includes an insulating housing (1) having four side walls interconnecting with each other and defining a receiving space (10) therein. Only one of the side walls defines a plurality of terminal grooves therein and a plurality of terminals (22) are mounted in said terminal grooves. A metallic shell (4) covers on the insulating housing and said shell (4) has a first resilient arm (431) extending in a first direction with a first contacting portion (4311) bending outwardly, and a second resilient arm (432) extending in a reverse direction toward the first resilient arm with a second contacting portion (4321) bending outwardly. The first and second resilient arms (431, 432) space away from each other in a transverse direction perpendicular to said first direction, and said first and second contacting portions (4311, 4321) offset with each other in said first direction.

1. Field of the Invention
The present invention relates to an electrical connector, and particularly to an electrical connector with a metallic shell therearound.
2. Description of the Related Art
For an electrical connector, especially the electrical connector in the field of high frequency communication, a metallic shell is usually provided to reduce the influence of the electromagnetic interference (EMI) by mechanically and electrically contacting with a casing, which is used for accommodating the electrical connector. TW patents No. M289243 and M277149 respectively disclose such an electrical connector with a metallic shell forming with a pair of resilient arms thereon. The pair of resilient arms respectively extend from a front portion of a side wall along a front-to-rear direction for contacting with the casing so as to release the current centralized thereon. Because the pair of resilient arms are formed at the same side of the side wall, the electrical connector may incline toward the other side of the side wall when the electrical connector is received in the casing with the metallic shell contacting with the casing. Therefore, a steadily electrical contact can not be provided between the metallic shell of the electrical connector and the casing. Hence, an electrical connector is needed to solve the problem.

Electrical connector having metal shell equipped with a pair of outwardly protruding resilent arms offset from each other


A method for testing latch-up phenomenon of a chip is provided. The chip is tested on a test platform, the test platform storing a test program of the chip for testing the chip. The method includes (a) obtaining the test program of the chip tested on the test platform, (b) obtaining pin data of the chip by the test program of the chip, (c) setting up an input pin of the chip with an initial value, and (d) providing a test current to the pin of the chip, and then measuring the current between a power end and a ground end of the chip to see if it exceeds a first predetermined value.

1. Field of the Invention
The invention relates to a universal test platform and related test method for latch-up, and more particularly, to a universal test platform and related test method for latch-up implemented by a test platform for developing a chip.
2. Description of the Prior Art
Please refer to FIG. 1 showing a cross-sectional view of a conventional CMOS and its associated parasitic circuit. In an integrated circuit (IC) two problems may occur: either a short circuit between a drain voltage node (VDD) and a source voltage node (VSS) may be formed due to a parasitic circuit effect, or the circuit cannot normally operate due to sudden voltage change when the power is off. Such kind of influence by a parasitic circuit is called a latch-up phenomenon. When a large amount of electrons is injected into an N-type substrate and received by a P-type well, the voltage drop between parasitic resistors Rs and Rw caused by a large current formed by the electrons is sufficient to conduct a low voltage in equivalent transistors T1, T2, resulting in a short circuit between VDD and VSS so that latch-up phenomenon occurs and the system fails. In order to prevent system failure due to latch-up, the resistance of the parasitic resistors Rs, Rw need to be lowered or the gain constant of the equivalent transistors be reduced. The gain constant of the equivalent transistors can be reduced by improving the IC manufacturing process. In addition, connecting the base of an N-type field transistor to the source voltage node can reduce the resistance of the parasitic resistors Rs, Rw, so that latch-up phenomenon is less possible to occur.
Please refer to FIG. 2 showing a conventional method for testing latch-up phenomenon in an IC 10. During the test, a test voltage 12 and an ammeter 14 is first installed between a power end (Vs) and a ground end (GND), and a trigger current 16 is then applied between a pin under test (PUT) and GND so that the ammeter 14 measures a current between Vs and GND. If latch-up phenomenon does not occur, the trigger current 16 is increased to continue the test. Such kind of latch-up test is standardized by JEDEC EIA/JESD78, in which each pin is required to sustain a trigger current 16 of 200 mA. The trigger current 16 increases 25 mA each time starting from 25 mA, and during the test the current measured between Vs and GND cannot exceed 100 mA. Generally, each different IC has its own test platform for developing and testing its functions. The test platform provides a parameter measurement unit (PMU), which is a set of power supplies providing current source and voltage source, as well as a set of units for measuring current and voltage. It is easy to execute latch-up test by PMU. Therefore, IC makers develop test programs on a test platform for different types of ICs according to JEDEC EIA/JESD78, to ensure that each IC passes the latch-up test.
As described above, latch-up phenomenon due to the parasitic circuit of the IC itself causes malfunction of the circuit system; thus each IC is required to pass the latch-up test by complying with the JEDEC EIA/JESD78 standard to ensure that the system operates normally. Since different ICs have their own test platforms, the IC makers can develop test programs on the test platforms for different types of ICs according to JEDEC EIA/JESD78 standard. However, it is troublesome to develop test programs for every different IC, since there are various types of ICs.

Universal test platform and test method for latch-up


A rotor hollow shaft for a rotor of an electric machine may include a cylinder barrel that is closed off on both sides by end flanges. On each side, a shaft journal may be positioned or formed on the end flanges. At least one of the shaft journals may include an access bore that provides access to a shaft cavity surrounded by the cylinder barrel. A leadthrough element may be fitted into the access bore so as to impart a sealing action with respect to the shaft cavity. The leadthrough element may extend through the shaft cavity to the shaft journal on the other side of the cylinder barrel, where the leadthrough element may likewise be fitted so as to impart a sealing action with respect to the shaft cavity. The leadthrough element may permit the leadthrough of a liquid or gaseous medium.

As is evident for example from DE 42 40 045 C1 and DE 203 07 198 U1, such rotor hollow shafts have long been known and are used wherever it is sought to achieve a construction which is as lightweight as possible. If the rotor hollow shafts are "assembled" from multiple parts, in particular a cylinder barrel and two end flanges, they are also referred to as "assembled" rotor shafts.
With regard to hollow rotor shafts of electric machines, it is also known for these to be flowed through by a medium in particular for the purposes of cooling the rotor. In this regard, reference is made for example to EP 0 659 308 or DE 199 13 199 A1, wherein the cooling medium is conducted via a pipe into the cavity and through this back to an outlet. It has however been found that this type of cooling is inadequate and is not in proportion to the outlay in terms of construction and to the impairment of the running characteristics of the motor.
Furthermore, electric machines are known in the case of which a medium, for example a lubricant or coolant, must be transported from one end side to the other, for example because an oil pan is provided on one side, but the oil is required at a different location. In this case, the rotor comprises purely a leadthrough function. Hitherto known hollow shafts are scarcely suitable for this function because the medium is supplied via a narrow duct formed into the shaft journal, and then distributes in the hollow shaft of significantly greater diameter in order to emerge again on the other side through a narrow duct. Such a leadthrough of liquid medium may be advantageous for the purposes of supplying the cooling medium to the stator, for example.
In the case of such machines with a leadthrough function, it is possible, owing to the considerable widening of the line cross section, for running roughness to arise, which is caused by the expansion of the medium into the hollow shaft and by the turbulence within the hollow shaft. Furthermore, a hollow shaft that is completely filled with liquid medium cancels out the advantage of the weight saving. In particular, with regard to use in the electric machine, filling a hollow cylinder with liquid has an adverse effect on the rotational inertia of said hollow cylinder. In this respect, the disadvantages of said prior art lie in the unduly large medium volume in the rotor shaft cavity and in the unduly heavy rotor shaft, and/or in the restricted possibility of optimization for a low weight.


Apparatus and process for the production of gaseous sulphur dioxide mixture for conversion to sulphur trioxide in a catalytic converter in the production of sulphuric acid by the contact process. Apparatus comprises the furnace to produce sulphur dioxide gas from elemental sulphur and a first dry air stream; means for feeding a first portion of the sulphur dioxide gas to a waste heat boiler to cool the gas; the improvement comprising combining a second portion of the sulphur dioxide gas exiting the furnace with a second dry air stream to provide a combined gaseous stream which bypasses the boiler and subsequently is combined with the cooled sulphur dioxide stream. The system provides use of a bypass valve which experiences only cooled sulphur dioxide containing gases with its attendant reduced corrosion. Further, the system may operate at higher temperatures than is common to provide further advantages.

In sulphuric acid manufacture from sulphur by the contact process, elemental sulphur is burned in a large excess of dry air in a sulphur furnace to produce a gaseous sulphur dioxide-air mixture at a temperature in the range of 900.degree.-1100.degree. C., containing 8-12% v/v SO.sub.2 and significant, excess oxygen. The downstream conversion of the resultant sulphur dioxide to sulphur trioxide requires 1 mole of oxygen for every 2 moles of sulphur dioxide and since there is a need for excess oxygen to drive the chemical equilibrium to low concentrations of sulphur dioxide there is always much more oxygen than required for stoichiometric combustion of sulphur to sulphur dioxide. The stoichiometric sulphur oxidation would produce a 21% sulphur dioxide gaseous mixture.
Downstream of the furnace in almost all sulphur burning plants is a waste-heat boiler, which cools the sulphur containing gas to, typically, 390.degree.-420.degree. C. for supply to a catalytic converter, while raising steam at pressures in the range 40-60 atm. These steam pressures correspond to boiling water temperatures in the range of 250.degree. to 275.degree. C.
The temperature of the sulphur dioxide containing gas fed to the converter is regulated at present by allowing a portion of the hot sulphur dioxide gas leaving the furnace to bypass the boiler through a hot gas bypass valve. The hot sulphur dioxide containing gas produced in the furnace is, however, very corrosive and few, if any, metallic materials provide a long and reliable life for the valve in the hot sulphur dioxide containing environment. In consequence, furnace temperatures are generally restricted and damper valves at normal design temperatures of about 950.degree. to 1050.degree. C. already have a limited life and require repairs at major plant shutdowns. Typical materials used for the valves include 310, 442 and 446 stainless steel, and several nickel based alloys. Ducting is typically brick lined and a typical valve uses a damper closing on a brick seat having a vertical movement of the valve. Unfortunately, such a valve seat does not provide a tight seal, which results in hot gas bypassing even when the valve is closed. In consequence, the boiler must therefor cool the gas below the desired temperature for entering the first bed of a converter in order to compensate for this hot gas leakage. This results in wasteful additional cooling surface in the boiler to achieve the required cooling.
A further variation on furnace and boiler design systems has air bypassing both the furnace and the boiler, with hot gas also bypassing the boiler. With both air and hot gas bypassing the boiler the temperature of the exit gas leaving the boiler is now higher than in the previous prior art arrangement, for the same converter gas inlet temperature and results in more efficient heat transfer. However, the furnace gas temperature is higher and the corrosive attack on the bypass valve is accelerated as compared to the earlier described system.
Both of the above bypass arrangements represent prior art systems which leave the hot gas bypass valve exposed to very high temperatures where the valve life is limited, despite the use of expensive heat and corrosion resistant alloys.
With plant sizes, steam pressures and boiling temperatures increasing, and lower temperature catalysts available on the market, cooling of the gases between the furnace and the converter by means of the boiler is becoming increasingly difficult as the typical fire-tube boiler used in sulphuric acid plants is becoming difficult to provide in many cases. In addition, the trend to higher efficiency in acid plants also tends to reduce the throughput air used, which further raises the furnace temperature and reduces the life of the bypass valve.


This disclosure relates to a driver assistance system for a motor vehicle comprising a vehicle headlight, which is designed to illuminate the surroundings of the motor vehicle, and an image capture unit, which is designed to evaluate light having a pre-definable first polarization direction for generating image data as a function of the surroundings of the motor vehicle. The vehicle headlight is designed, during normal operations, in which a pre-definable light output is provided by the vehicle headlight, according to a pre-definable modulation pattern and/or with a pre-definable portion of the light output, to generate linearly polarized light with a second polarization direction to provide lighting for the surroundings. In addition, this disclosure relates to a motor vehicle with such a driver assistance system and a corresponding method.

In modern motor vehicles, particularly including motor vehicles with internal combustion engines and/or electric motors, the recognition of the environment by computer-based assistance systems is playing an increasingly important role. Sensor data of various kinds are evaluated as a basis for the creation of a three-dimensional virtual model of the real environment. This includes, in addition to GPS data, infrared and ultrasound sensor data, and, above all, image data that is produced by an image capture unit, which usually manifests as a 2D camera and which performs a scan in the visible wavelength range. Especially in the direction of travel, aligned camera systems benefit here from the improved illumination through the existing headlight systems of the motor vehicle. The visible light spectrum of the headlight clearly increases the accuracy of the camera detection, but reduces the quality of the images in fog and similar poor visibility, because the particles in the air reflect the emitted light and thus worsen the image.
According to the current state of the art, the illumination of the camera field of view is largely carried out by the headlights of the motor vehicle. In this case, great care is taken to minimize the glare for the driver in the event of fog. Since the high light intensity of the high beam in the fog leads to reflections, modern motor vehicles provide additional fog lights whose function is optimized to illuminate the road without blinding the driver. For this purpose, an area of the roadway is illuminated, which is not necessarily evaluated by built-in camera systems. These driver assistance systems encounter the same problems that a human driver faces, i.e., significant visibility deterioration in fog.
A program-controlled computing unit, for example, a microcontroller or a microprocessor, calculates the surroundings of the motor vehicle from the sensor input data. Reflections on wet pavement, and on reflective buildings and surfaces such as rear windows of other vehicles, increase the noise in the input data of the camera. A previously uniquely identifiable object can be difficult for a computer algorithm implemented using a computer program to recognize due to the superimposition of reflections. This noise distorts the signal of the image and introduces an element of uncertainty. Fog and water vapor at a mid-to-long distance (30 meters to 500 meters) make the contours of objects blurry. This makes it difficult for the driver assistance system to recognize patterns. The signal-to-noise ratio deteriorates, especially with increasing distance.
In this context, DE 10 2012 018 121 A1 discloses an image capture device for capturing images of the surroundings of a motor vehicle, comprising a stereo camera unit which has a first optical device for capturing images of the surroundings and a second optical device at a distance from the first optical device. One of the optical devices is assigned at least one polarizing filter element for at least partially absorbing light. The one of the optical devices is arranged and adjustable between at least one use position in which the polarizing filter element is provided at least partially in a detection range of the one of the optical devices, and a non-use position, in which the polarizing filter element is provided outside the detection range of the one of the optical devices.
Moreover, DE 10 2014 205 204 B3 discloses a camera-based driver assistance system with a stereo camera having first and second image sensors for generating image data of the vehicle surroundings, in which the image data are evaluated by an image evaluation unit and a polarization filter is connected upstream of the second image sensor that transmits horizontally polarized light. The image evaluation unit is provided to compare the intensities of the frames of image data simultaneously generated by the first and second image sensors and to display the surface condition of the road taken by the stereo camera depending on the intensity ratio.
DE 10 2013 207 148 A1 proposes a light propagation time camera system comprising a light propagation time camera, which is designed to provide a preferred polarization of light, and a light, which is designed to emit polarized light.
The features and advantages of the present embodiments will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

Linearly polarized light emission by a vehicle headlight for use in a camera-based driver assistance system


A hydrocarbon cooling system including a housing having a substantially rectangular base defining a diagonal, a front wall defining a first air inlet, a back defining a first air outlet, and a pair of side walls. The cooling system includes a condenser mounted within the housing adjacent the first air inlet; a compressor; an evaporator; and a fan mounted within the housing and defining an axis. The fan is positioned such that a vertical plane aligned along the axis defines a first a non-perpendicular angle relative to a second vertical plane aligned perpendicular to the back of the housing. The fan creates a first horizontal airflow path, which enters the housing through the first air inlet and exits the housing through the first air outlet. The first horizontal airflow path induces a second horizontal airflow, which moves around the housing along a line substantially parallel to the diagonal.

1. Field of the Invention
The present invention relates to refrigeration systems, particularly refrigeration systems that use hydrocarbon refrigerants and means for venting hydrocarbon refrigerant leaks.
2. Description of the Related Art
Refrigerators commonly include an insulated cabinet, the interior of which is cooled by a cooling system. The cooling system is typically disposed within a housing, which is located beneath or behind the cabinet. The cooling system generally includes a compressor; a condenser fluidly connected to the compressor; and an evaporator fluidly connected to both the compressor and the condenser and in thermal communication with the interior of the cabinet. In operation, a refrigerant gas enters the compressor where it is compressed under high pressure. The compressed refrigerant gas then flows to the condenser where it is cooled in a series of coils and is condensed into a liquid. The liquid refrigerant then flows to the evaporator where the liquid refrigerant absorbs heat from the interior of the cabinet, thereby cooling the interior and converting the refrigerant liquid back to a gas. The refrigerant gas then flows back to the compressor where the cycle is repeated. A fan is typically incorporated in the cooling system to cool the compressor and force air through the condenser coils.
An effective refrigerant should be capable of readily evaporating at low temperatures and compressing at high pressure without decomposing. Consequently, compounds that are ideal for use as refrigerants are stable compounds having low evaporation temperatures. In the past, CFCs (chlorofluorocarbons) have been used as refrigerants. However, it is believed that CFCs are harmful to the environment and, as a result, hydrocarbon refrigerants, such as propane and isobutanes, have been used in place of CFCs. Unfortunately, hydrocarbon refrigerants have a Low Flammability Limit, which means that even a small hydrocarbon refrigerant leak in the housing could result in a build up of hydrocarbon refrigerant to a concentration level above the Low Flammability Limit. A concentration of hydrocarbon refrigerant above the Low Flammability Limit is sufficient to trigger an explosion in the presence of oxygen and a flame or spark.
Hydrocarbon refrigerant leaks are, to some degree, flushed from the housing by the fan. The fan, often referred to as the condenser blower, is typically located behind the condenser near the back of the housing. The fan is typically positioned such that its axis is perpendicular to the back of the housing. The fan draws air in through the front of the housing, over the condenser coils and out through the back of the housing. This airflow path may not reach the compressor and, thus, may not sufficiently cool the compressor. In addition, the air flows perpendicular to the back of the housing such that, when the air reaches the building wall behind the refrigeration system, it is deflected in both the upward and downward directions. The air that is forced upward flows up above the cabinet and ultimately mixes with the ambient air above the cabinet. However, the air that is forced downward flows beneath the housing and back to the front of the housing, where it may then be drawn back into the housing. Consequently, any hydrocarbon refrigerant contained within this air is re-circulated back into the housing, thereby permitting the accumulation of hydrocarbon refrigerant, possibly to a level above the Low Flammability Limit.
Attempts have been made to prevent hydrocarbon refrigerant leaks by reducing the number of joints in the condenser, where leaks are most likely to occur. In addition, the operating pressure may be reduced in an effort to prevent hydrocarbon refrigerant leaks. Attempts have also been made to develop systems for detecting hydrocarbon refrigerant leaks. Such systems may monitor the thermal dynamic parameters of the system and/or the electrical consumption of the compressor, or may sense the molecules of hydrocarbon refrigerant in the air. Despite these attempts, a need remains for a system that ventilates the cooling system area to effectively flush, dissipate and dilute hydrocarbon refrigerant leaks from the housing.

Apparatus for and method of venting hydrocarbon refrigerant leaks


A combination cutter and stencil device. The device includes a cutter having a cutting peripheral edge, and a gripping portion, and a stencil plate with openings arranged in a design. The stencil plate is permanently or temporarily fixed to the cutter. Once material is cut to shape with the cutting peripheral edge, the stencil plate is placed on the cut shape, to allow the design to be created by application of stencil material through the stencil plate openings. Also disclosed are methods of cutting and stenciling using such a device.

There are numerous situations in which a relatively soft, planar material needs to be cut into a particular shape, and then decorated with paint or a similar material, to create on the cut shape a design. Examples include foodstuffs such as cookies, biscuits, canapes, and tea sandwiches, as well as items such as ceramic tiles and ornaments. Because cookies are the most common example of such, much of the following description will be directed to cookie cutting and decoration, although this should not be taken as a limitation to the scope of the invention.
To make decorated cookies, it is necessary to first cut the cookie from cookie dough using a cookie cutter, and then decorate the cookie using frosting, sprinkles, candy, or edible paint, for example. Frosting and painting require artistic ability and a steady hand for good results.
It is possible to more carefully decorate a cookie using a cookie stencil, which is a flat plate with a number of openings arranged to create a design. The plate is placed on the cookie, and frosting or paint is applied through the openings onto the cookie. When the stenciling is done, the stencil is lifted off of the cookie, and the cookie is baked.
However, since the stencil is not a part of the cookie cutter, the baker needs to keep separate sets of cookie cutters and stencils, which uses valuable kitchen shelf space, and requires additional organization. Also, in use the stencils must be carefully lifted from the cookie after the design is complete so as not to smear the design, or damage the fragile cookie dough. The flat stencil plates are fairly difficult to carefully grip and remove in this manner. Thus, stencil plates are relatively difficult to use and may not result in a high quality, pleasingly decorated cookie.
The shape of such stencil plates, and of the design carried by the plate, bears no relationship to the shape of the cookie. This can result in less than all of the design fitting on an already-cut cookie, or require the cookie to be overly large in order to carry the whole design. Also, because the cutters and stencils are separate, the stencil design cannot be integrated with the cookie shape.
Stencilling is also distinguished from embossing. Embossing requires a structure which interacts with and shapes the material. Thus, the embossing surface cannot be flat. In contrast, stencilling contemplates openings in a plate which sits very near (and preferably directly on) the material, but which do not themselves have any effect on the material.

Combination cutter and stencil and method of using same


The present invention aims at provision of a pressure-sensitive adhesive composition that affords a cured product having good adhesive property. Reduction of the amount of tackifier resin to be used, which is attributable to the good adhesive property, is a secondary object of the present invention. The above-mentioned problem can be solved by a pressure-sensitive adhesive composition containing (A) a polyoxyalkylene polymer having at least one alkenyl group in one molecule, (B) a compound having 1 to 3 hydrosilyl groups on average in one molecule, and (C) a hydrosilylation catalyst as essential components.

Development of a curable composition obtained by reacting a polyoxypropylene polymer having an alkenyl group and a compound having a hydrosilyl group in the presence of a platinum catalyst for use in various applications including re-peeling has been considered in view of the properties such as rapid curing ability, good curing depth, and the properties based on the structure such as affinity for various substrates, hydrophilicity, chemical stability and the like. As a method for obtaining such curable composition, a curable composition has been proposed which is obtained by reacting a polyoxypropylene polymer having an alkenyl group with organohydrogen polysiloxane having a silicon bonded hydrogen in one molecule in the presence of a platinum catalyst (e.g., JP-A-60-55056). As a method for improving compatibility and mechanical property of this curable composition, moreover, a method using, as a compound having a hydrosilyl group, organohydrogen polysiloxane having a phenyl group on the side chain has been proposed (e.g., JP-A-7-300555). In addition, a pressure-sensitive adhesive composition comprising a polyoxypropylene polymer having an alkenyl group, a compound having a hydrosilyl group, and a hydrosilylation catalyst comprising a tackifier resin has been proposed (e.g., JP-A-4-145188). However, produces resulting from curing these compositions do not necessarily have good property as an adhesive.
As other pressure-sensitive adhesives using a polyoxyalkylene polymer, pressure-sensitive adhesives using urethane crosslinking are known (e.g., JP-A-7-310066), and they have been reported to have superior properties such as adhesion to the skin, moisture permeability, water absorbability and the like. Due to urethane crosslinking, however, they are associated with problems including difficult control of curing speed, remaining unreacted isocyanate feared to have toxicity and the like.


Universal solid support oligonucleotide synthesis reagents, oligonucleotide synthesis processes, and reagents for cleaving oligonucleotides from solid supports are disclosed. Oligonucleotide synthesis reagents have the following general formula: EQU SS--R.sup.6 --O--R.sup.3 I. wherein SS is a solid support; R.sup.6 is ##STR1## where R.sup.5 is hydrogen or alkyl and R.sup.4 is a phosphate protecting group; and R.sup.3 is a ring moiety having vicinal groups --XR.sup.1 and --YR.sup.2 wherein each of X and Y is independently selected from the group consisting of O, S and NH and one of R.sup.1 and R.sup.2 is a blocking moiety and the other is hydrogen or a hydroxy protecting group. Oligonucleotide cleaving reagents include methylamine and/or ammonium hydroxide and trimethylamine.

The present invention relates generally to the fields of chemistry and biology. More particularly, the present invention is directed to compositions and methods for use in the synthesis of oligonucleotides (e.g., DNA and RNA sequences).
A variety of synthetic approaches have been developed for preparation of oligonucleotide sequences. Typically, oligonucleotides are synthesized utilizing a building block approach which involves the sequential addition of nucleotides onto a growing oligonucleotide chain immobilized on to a solid support. Because every DNA oligonucleotide may have any of 4 different initial nucleotides, it is necessary to maintain a supply of 4 different nucleoside (A, C, G and T) loaded solid supports to be able to synthesize any given DNA sequence. In the case of DNA synthesis, the first nucleoside from the 3' end of the DNA sequence is typically preloaded on the solid support through an ester linkage. For example, if the sequence that is to be synthesized contains a T nucleoside at the 3' end, a T support is employed and the balance of the nucleotides in the DNA sequence added thereto (for example, using an automated DNA synthesizer). At the end of the total DNA synthesis, the oligonucleotide is cleaved from the solid support through the hydrolysis of the ester linkage. Taking into consideration RNA synthesis procedures, an additional 4-different nucleoside loaded solid supports must be available to the user. Similar considerations apply if any specialty modified nucleoside is desired at the 3' end.
Maintaining a supply of at least 8 different prederivatized solid supports is inconvenient and expensive. An additional consideration is the relatively short shelf life of nucleoside derivatized solid supports. Typically, after one year storage such solid supports are not longer usable. There is also the possibility that synthetic procedures may be initiated mistakenly with the wrong support leading to disastrous consequences in the final applications of the oligonucleotides.
In order to alleviate these problems some researchers have pursued developing some type of universal solid support. For example, deBear et al. derivatized glass supports with 2' (3')-O-benzoyluridine 5'-O-succinyl so that the uridine moiety is linked to the glass via an ester (succinate) linkage. de Bear et al., Nucleosides and Nucleotides 6, 821-830 (1987)!. Oligonucleotide synthesis takes place by adding nucleotide monomers to the 2' or 3' position of the uridine. Following the synthesis, the new oligonucleotides can be released from the glass, deprotected and cleaved from the uridylyl terminus in one reaction. Since the uridyl functionality is cleaved from the solid support in this cleaving reaction, the support is not available for subsequent oligonucleotide syntheses.
Crea and Horn suggested a similar approach which involved preparing the dimer 5'-O-p-chlorophenylphospho-2' (3')-O-acetyluridilyl-2' (3')-3'!-5'-O-dimethoxytritylthymidine p-chlorophenylester and attaching the dimer to cellulose via a phosphate linkage. The 5' position of the thymidine is available for oligonucleotide attachment and synthesis. R. Crea & T. Horn, Nucleic Acids Research 8, 2331 (1980)!. The subsequent use of aqueous concentrated ammonia results in the release of the synthesized oligonucleotide from the cellulose leaving the uridine portion of the dimer attached to the cellulose. Although Crea and Horn utilized the reactive vicinal groups on the uridine as the release site for the oligonucleotide from the uridine the solid support suggested in this reference is not a universal solid support since the initial oligonucleotide is incorporated in the solid support reagent and a different support is required for oligonucleotides incorporating different first nucleoside.
More recently, Schwartz et al. attached an adapter, 2' (3')-O-dimethoxytrityl-3' (2')-O-benzoyluridine-5'-O-(2-cyanoethyl N,N-diisopropylphosphoramidite, to a thymidine derivatized polystyrene and synthesized an oligonucleotide from the O-dimethoxytrityl position of the uridine. M. E. Schwartz, R. R. Breaker, G. T. Asteriadis, and G. R. Gough, Tetrahedron Letters, Vol. 36, No. 1, pp 27-30, 1995! While this approach provides a universal solid support for oligonucleotide synthesis, the cleaving step releases the adapter and the thymidine from the support and then cleaves the synthesized oligonucleotide from the uridine. Thus, the purification process requires removing the thymidine linker and the cleaving processes leaves the solid support unavailable for subsequent uses.
The aforementioned solid supports and methods for their use disadvantages in terms of the convenience and efficiency of the subsequent oligonucleotide cleaving steps. When ammonia which has been widely accepted as a safe reagent for DNA synthesis is utilized for cleaving, as taught by deBear et al., the cleavage time is as long as 24 hours at 65.degree. C. In view of the growing trend to produce oligonucleotides as quickly as possible, this is an unacceptably long period of time. Decreasing the time required for cleaving the uridylyl from an oligonucleotide at the uridine 3' position typically uses a lead (II) ion catalyst system or the action of strong alkali hydroxides. Necessarily these processes require a separate isolation step to remove the lead ion. Additionally, when strong alkali bases are used in the cleaving processes, considerable side reactions in the form of cytosine deamination occur.
Recent improvements in the automation of simultaneous multiple oligonucleotide synthesis (whereby several oligonucleotides are synthesized simultaneously) further highlight the desirabilty of using a single universal solid support for the synthesis of oligonucleotides. Any requirement to dispense several different nucleoside preloaded solid supports on a DNA synthesizer clearly complicates the synthesis automation. Therefore, it would be highly desirable to have a universal solid support to synthesize any nucleic acid.
It is an object of the present invention to provide methods and compositions for use in the synthesis of oligonucleotides which ameliorate some of the problems encountered with the prior art methods and compositions. More particularly, it is an objective of the present invention to provide reusable oligonucleotide synthesis reagents which can be used for synthesizing a variety of oligonucleotide independent of the initial nucleoside. It is another objective to provide cleaving reagents and cleaving methods which substantially decrease the time required to cleave oligonucleotides after synthesis.

Universal solid supports and methods for their use


A device for the semiautonomous support of a parking process of a vehicle, such as a motor vehicle, having a steering device for the steering movement of wheels of the vehicle, having a control device for controlling the steering device, the control device having a computing device for processing input values to form an output value that controls the steering device; the computing device being developed for processing a steering angle, that is maximally achievable at the wheels of the vehicle, together with a steering wheel angle, that is maximally achievable in response to the respective conditions, to form an output value that is designated as a steering wheel angle.

A device for the semiautonomous support of a parking process for vehicles is described in German Patent Application No. DE 10 2005 008 176 A1.
In contrast to fully autonomous devices for the support of parking processes, in the case of semiautonomous devices, that is devices which make available support power semiautonomously during the parking of vehicles, the cooperation of a driver is relied upon. In the case of devices for semiautonomous support of a parking process, the driver generally at least either accelerates and brakes, or intervenes in the parking process by steering. In contrast to these devices that operate semiautonomously, in the case of fully autonomous devices, that is, devices which put together fully autonomous support power during the parking process, neither steering not braking and/or giving gas is expected of the driver.
Furthermore, in the case of devices which autonomously support the parking process of vehicles, intervention is only conditionally possible.
Devices for the semiautonomous support of a parking process are used in land-bound vehicles, especially in motor vehicles equipped with an internal combustion engine, such as passenger cars.
German Patent Application No. DE 10 2005 008 176 A1 describes an arrangement for automatic steering that superposes steering torque on the steering wheel of the vehicle that is to be parked. If the steering torque is greater than the frictional forces between tires and roadway, the vehicle is automatically steered. However, the driver controls the steering wheel motion of the vehicle independently. The device described in German Patent Application No. DE 10 2005 008 176 A1 for the semiautonomous support of a parking process does not intervene independently in the control of the steering wheel motion of the vehicle. However, using sensors mounted on the outside of the vehicle, it measures the parking space and also ascertains a desired entry trajectory. The entry trajectory is the curve that is covered optimally by the vehicle during parking.
German Patent Application No. DE 10 2005 008 176 A1 also describes an arrangement held in reserve which ascertains the maximum possible steering speed. It also describes that an arrangement is held in reserve which determines the steering speed, that is, the speed for the application of steering torque to a steering wheel and/or a steering shaft via appropriate assemblies. In this context, an adjustment is produced in a computing device between the calculated steering speed and the maximum possible steering speed. If the calculated steering speed is greater than the maximum possible steering speed which is able to apply the means for automatic steering, either an instruction is output to the driver to lower the speed, or the speed is automatically reduced via a limiting device.
If, during parking of the vehicle and being aided by the semiautonomously working device, the driver does not operate the steering wheel, the steering torque required for controlling the steering wheel is applied exclusively by a steering device, that is, a steering actuator device, such as an electric motor. Such electric motors are part of appropriate steering devices that are also known as EPS, i.e., electronic power steering.
However, for large steering angles, large steering torque generally has to be applied, particularly when the vehicle to be parked is at a standstill. High currents are then required of the steering device, which may amount, at times, up to 100 Amps. In such high-load situations, diverse problems appear in the conventional devices. For instance, the conventional devices are not able to park the vehicle that is to be parked in one reverse move, but require at least one additional forward move. This problem occurs particularly in small parking spaces. In such cases, if one wants to achieve a low longitudinal distance from a lateral limitation, such as a curb, each change in direction is accompanied by a maximum steering angle. To be sure, in a case like that the vehicle is usually standing still, while the steering device is instructed to execute a maximum steering angle.
Mechanical steering systems used up to now have unfavorable force transmission, particularly in the case of large steering angles, so that particularly large steering torques have to be applied if a maximum steering angle is to be achieved.
The problems are aggravated if the pavement, on which the vehicle is located, and/or the tire quality used by the vehicle displays a particularly firm grip. It then sometimes becomes possible only to achieve a partial steering angle.
The problem is further aggravated if the battery supplying the steering device with current is weak, or if a steering assembly of the steering device detects a high thermal load, whereby the maximum deliverable steering torque is reduced. Even in such cases, the desired steering angle can no longer be fully implemented.
The maximum steering angle that can be achieved is therefore greatly different, even within a single parking process, and is not predictable in all cases.

Device for the semiautonomous support of the parking process of a vehicle


A disc-shaped optical data recording medium has a signal recording layer for reading and/or writing data using light, and a 10 μm to 200 μm thick transparent protective layer disposed over the signal recording layer. The optical data recording medium includes a protrusion projecting from a surface of the transparent protective layer on a light-incidence surface side to which light is emitted to the signal recording layer. The protrusion is disposed in an area between a center hole and a clamping area where the optical data recording medium is held when reading and/or writing data in the signal recording layer.

1. Field of the Invention
The present invention relates to a disc-shaped optical data recording medium having a signal recording layer for recording and/or playing information by emitting a light beam thereto, and a transparent protective layer 10 μm to 200 μm thick disposed over the signal recording layer. The invention also relates to a method for manufacturing this optical data recording medium, and to a method for clamping the optical data recording medium.
2. Description of Related Art
Optical discs are known and widely used as a high capacity data storage medium for high density recording and playback of information using a laser beam. These optical discs are broadly categorized as read-only, incrementally writable (multisession), and rewritable. Typical of read-only discs are Compact Discs (CDs) storing audio content and Laser Discs storing video content such as movies. Both incrementally writable (multisession) and rewritable media are widely used in the computer industry, for example, for storing text documents and still image files.
These optical discs typically have a data layer disposed to one main side of a 1.2 mm thick transparent substrate. A protective overcoat is then applied to the data layer, or a protective disc identical to the transparent substrate is bonded by adhesive to the data layer. See, for example, Japanese Laid-Open Patent Publication No. 2001-093193, paragraph [0015] and FIG. 1, and Japanese Laid-open Patent Publication No. 2002-042376, paragraph [0019] and FIG. 1.
Development and introduction of Digital Versatile Discs (DVD), a high capacity optical disc medium, has made it practical for even end-users to record moving picture content (such as movies and video) together with audio to an optical disc. High density media such as DVD have been achieved by using a shorter wavelength laser and an objective lens with a large numeric aperture (NA). However, shortening the beam wavelength and increasing the NA also reduce the tolerance for tilt, the inclination of the disc to the direction of laser beam emission.
Tolerance for tilt can be improved by using a thinner substrate. With DVD media this means, for example, using a 0.6 mm thick substrate assuming a 650 nm laser and 0.60 NA. Because a 0.6 mm thick substrate is mechanically weak and would thus increase tilt, DVD discs have two such substrates bonded together with the data recording surfaces on the inside between the substrates.
By using this laminated structure a transparent reflective layer of gold or silicon, for example, is formed on the data recording surface of one of the two substrates, and a conventional reflective layer of aluminum, for example, is formed on the data recording surface of the other substrate. The substrates are then bonded together with these data recording surfaces facing each other on the inside, resulting in a single-sided, double-layer DVD that can be read from one side of the disc, that is, from the side of the substrate having the transparent reflective layer over the data recording layer. Rewritable DVD media with a similar double-layer construction are also available, but the data recording surface in this case is a rewritable thin-film recording layer instead of a metal mirror layer.
Using a blue-purple laser with an approximately 400 nm wavelength has also been proposed as a way to achieve even higher recording densities. One method uses an approximately 0.1 mm thick transparent protective layer on the read/write side and forms an ultrafine laser spot using an approximately 0.85 NA lens for signal reading and/or writing. The transparent layer can be formed with the following two methods.
(A) Bonding a transparent substrate slightly less than 0.1 mm thick to the signal surface side of a 1.1 mm thick signal substrate using adhesive.
(B) Coating the signal surface side of a 1.1 mm thick signal substrate with an approximately 0.1 mm thick transparent resin layer.
In method (A) a polycarbonate sheet manufactured by casting, for example, is used as the transparent substrate. Thickness variation in such cast sheets is minimal at approximately +/−1 μm. The thickness of the adhesive used to bond this polycarbonate sheet to the signal substrate is also thin and can be easily formed to a uniform thickness. As a result, a transparent protective layer with uniform thickness can be formed on the recording/playback side of the disc.
With method (B) it is difficult to form a uniformly thick coating because of the thickness of the transparent resin, but a low cost, high density optical disc can be achieved because it is not necessary to use sheets manufactured in a high cost casting process.

Optical data recording disc with protrusion between clamping area and center hole

Matsushita Electric Industrial Co., Ltd.


In an embodiment a switching device includes at least one stationary contact in a switching chamber containing a gas comprising H2 and one movable contact in the switching chamber, wherein the switching chamber has a switching chamber wall and a switching chamber base, and wherein the switching chamber at least partially comprises a polymer material configured to release hydrogen when heated.

One possible application for switching devices of this kind, in particular power contactors, is opening and isolating electrical battery circuits, for example, in motor vehicles such as electrically or partially electrically driven motor vehicles. These may be, for example, purely battery-operated vehicles (BEV: "battery electric vehicle"), hybrid electric vehicles which can be charged via a power outlet or charging station (PHEV: "plug-in hybrid electric vehicle") and hybrid electric vehicles (HEV). In general here, both the positive and the negative contact of the battery are isolated using a power contactor. This disconnection is performed in normal operation for example when the vehicle is at a standstill and also in the event of a disturbance such as an accident or the like. The main task of the power contactor here is to switch the vehicle to a deenergized state and to interrupt the flow of current. In particular, in the event of a fault, switching arcs occur when the current is interrupted. These switching arcs have to be quenched in order to safely interrupt the current flow and prevent destruction of the switch.
A hydrogen-containing gas filling and in addition additional permanent magnets, so-called blowout magnets which can deflect the arcs, in the region of the arcs which occur are usually used in order to quench the arc. By way of example, European Application No. EP 1168 392 A1 describes blowout magnets of this kind.
Furthermore, outgassing plastics such as unsaturated polyester or nylon in the vicinity of an arc can lead to an improvement in the quenching behavior. However, the disadvantage of said outgassing plastics is their high carbon content which, in the event of evaporation of the plastic, can lead to conductive coatings on the chamber inner wall, in particular owing to the formation of graphite, and as a result adversely affect the dielectric strength or, in the worst case, can lead to a short circuit of the contacts.