A processing system for processing a substrate with a plasma comprises a processing chamber configured for containing a plasma and a substrate support. Electrodes are coupled to the substrate support and an RF power source is coupled to each of the electrodes for biasing the electrodes to create a DC bias on a substrate positioned on the supporting surface. A first comparator having first and second inputs is electrically coupled to one of the electrodes with an isolating device being coupled between the first and second inputs to isolate the first input from the bias on the one electrode. The comparator has an output reflective of a voltage difference between the first and second inputs. A second comparator has a first input coupled to the first electrode and a second input coupled to the second electrode, and has an output reflective of a voltage difference between the first and second inputs resulting from the bias difference between the first and second electrodes.

This invention relates generally to the processing of a substrate utilizing a plasma in the production of integrated circuits, and specifically relates to the determination of substrate bias parameters in a plasma processing system, such as one utilizing an electrostatic chuck to secure a substrate to a susceptor during processing.
Gas plasmas are widely used in a variety of integrated circuit fabrication processes, including plasma etching and plasma deposition applications, such as PECVD. Generally, plasmas are produced within a processing chamber by introducing a low-pressure process gas into the chamber and then directing electrical energy into the chamber for creating an electric field therein. The electric field creates an electron flow within the chamber which ionizes individual gas molecules by transferring kinetic energy to the molecules through individual electron-gas molecule collisions. The electrons are accelerated within the electric field, producing efficient ionization of the gas molecules. The ionized particles of the gas and the free electrons collectively form what is referred to as a gas plasma.
Gas plasmas are useful in a variety of different processes. One commonly used plasma process is a plasma etch process wherein a layer of material is removed or xe2x80x9cetchedxe2x80x9d from a surface of a substrate. In an etch process, the ionized gas particles of the plasma are generally positively charged, and the substrate is negatively biased such that the positively ionized plasma particles are attracted to the substrate surface to bombard the surface and thereby etch the substrate surface. For example, a substrate might be etched to remove an undesirable material layer or coating on the substrate before another layer is deposited. Such a pre-deposition etch process is often referred to as etch cleaning of the substrate.
Other common plasma processes involve deposition, wherein a material layer is deposited upon the substrate. Chemical vapor deposition, or CVD, for example, generally involves the introduction of material gases into a processing chamber wherein the gases chemically interact and form a material layer or coating on the exposed substrate surface. A gas plasma can be utilized to enhance the chemical interaction. Consequently, such a CVD deposition process utilizing a plasma is referred to as plasma-enhanced CVD or PECVD. The plasma is utilized to provide energy to the process and enhance the deposition quality and/or deposition rate. Other plasma deposition processes also exist as are commonly understood by a person of ordinary skill in the art.
During plasma processing of a semiconductor substrate, it is often useful to apply an accelerating voltage to the surface of the substrate. The accelerating voltage or substrate bias is utilized to accelerate ions or other charged particles within the plasma to the substrate surface. In an etch process, the charged plasma particles are attracted to the substrate surface to actually bombard the surface and provide the etch as discussed above. In a deposition process, such as PECVD, the energy provided by such charged particle bombardment may be utilized to further enhance the deposition rate or to enhance the deposition quality, as mentioned above.
Generally, biasing of the substrate in plasma enhanced etch and deposition processes is accomplished by capacitatively coupling an RF field from electrodes in the processing chamber, through the substrate, and to the exposed substrate surface which is to be etched, or which is to receive a deposited material layer. Specifically, the electrodes, which are positioned within a susceptor or substrate support, are biased with an RF power supply to create an RF field. The RF field is then capacitatively coupled through the susceptor and substrate to create a relatively uniform DC bias potential across the exposed substrate surface. The substrate surface DC-bias, in turn, affects the plasma, as discussed above, to enhance the etch or deposition process.
Within a plasma processing system, the plasma will usually have particular non-uniformities associated therewith. For example, the plasma density is often greatest in the center of the plasma, due to edge effects proximate the sides of the processing chamber. The non-uniformities in the plasma translate to discrepancies within the etch and deposition processes in which the plasma is utilized. For example, an undesirable variation in etch rate may occur wherein the etch rate proximate the center of the substrate is greater than the etch rate proximate the outer edges of the substrate. Furthermore, within a plasma-enhanced deposition process, the deposition may be affected proximate the center of the substrate differently than at the edge of the substrate thus creating a non-uniform deposition layer and a non-uniform deposition rate radially across the substrate.
Attempts have been made in the art to address such plasma non-uniformities in a plasma processing system. For example, U.S. Pat. application Ser. No. 09/565,606 entitled xe2x80x9cImproved Apparatus and Method for Plasma Processing of a Substrate Utilizing an Electrostatic Chuck,xe2x80x9d filed May 4, 2000, now U.S. Pat. No. 6,431,112 discloses a plasma processing system which selectively adjusts the bias on the substrate to offset plasma non-uniformities in the system; that application is incorporated herein by reference in its entirety. While that system improves the overall plasma process, it has been difficult to achieve precise selectivity in varying the substrate bias. Therefore, it is an objective of the present invention to provide more precise adjustments to the substrate bias in a plasma processing system for addressing non-uniformities in the plasma.
In accordance with another aspect of the invention, it is desirable to provide precise bias control even in a system utilizing an electrostatic chuck. Particularly during integrated circuit fabrication, the substrate being processed is supported within the processing chamber by a substrate support or susceptor. Oftentimes, the substrate is physically secured on the susceptor during processing, such as to improve heat transfer between the substrate and susceptor. One way of securing a substrate involves the use of an electrostatic chuck (ESC), which uses an applied DC bias to the substrate to electrostatically attract and secure the substrate to the susceptor. Electrostatic chucks are known in the art with suitable designs being shown in U. S. patent application Ser. No. 09/565,606 entitled xe2x80x9cImproved Apparatus and Method for Plasma Processing of a Substrate Utilizing an Electrostatic Chuck,xe2x80x9d filed May 4, 2000, now U.S. Pat. No. 6,431,112 noted above, and in U.S. Pat. No. 5,117,121, which is also incorporated herein by reference. Electrostatic chucks will usually use the same electrodes as are used to bias the substrate. This practice has made precise measurement of the substrate surface bias levels even more difficult due to the effect of the electrostatic clamping voltage on such measurement. Therefore, it is a further objective to provide more precise biasing of a substrate to address plasma non-uniformities within a processing system utilizing an electrostatic chuck.
It is still another objective of this invention to address the above-discussed objectives without adversely affecting the desired biasing of the substrate surface which is necessary for plasma processing.
The processing system, in accordance with the principles of the present invention, provides more precise monitoring of substrate bias within a plasma processing system for improved substrate bias control. Additionally, the inventive system provides such precise bias measurements in combination with a system utilizing an electrostatic chuck. Measurements provided by the system may be used to vary the bias across selected portions of the exposed substrate surface for more uniform plasma processing, or selectively varied plasma processing.
To that end, the processing system comprises a processing chamber for containing a plasma. A substrate support is mounted within the chamber for supporting the substrate proximate the plasma. A plurality of electrodes, such as first and second electrodes, are coupled to the substrate support and are positioned proximate the supporting surface. The electrodes are electrically isolated from one another. A RF power source is coupled to each of the electrodes for biasing the electrodes with RF electrical energy. The biased electrodes are operable in conjunction with the substrate support for creating a DC bias on the exposed surface of the substrate positioned on the supporting surface of the substrate support.
In accordance with one aspect of the present invention, a plurality of comparators are utilized to monitor the bias on the individual electrodes for the purpose of selectively varying the bias. More specifically, the first comparator has first and second inputs which are electrically coupled to one of the electrodes. An isolating device is coupled between the inputs and is operable for isolating the first input from the bias on the monitored electrode which is created by the RF power source. The comparator has an output reflective of a voltage difference between the first and second inputs which results from the electrode bias created by the RF power source. Since the first input is isolated from the electrode bias created by the RF power source, the output of the first comparator is reflective of electrode RF bias.
A second comparator provides an indication of the voltage-bias differential between the first and second electrodes. With the output from the first comparator coupled to the one electrode, and the output of the second comparator coupled between both electrodes, the bias level on each of the individual electrodes may be obtained. Specifically, the second comparator has a first input coupled to the first electrode and a second input coupled to the second electrode. The comparator has output reflective of a voltage difference between the first and second inputs which results from the bias difference between the first and second electrodes. With the signal reflective of the bias on one electrode and a signal reflective of the bias differential between the two electrodes, the relative bias on the other, unmeasured electrode, may be obtained. In that way, the relative bias on the first and second electrodes may be monitored so that the bias may be optimally adjusted.
The monitored outputs of the comparators may be utilized to determine the relative bias on the electrodes so that the bias may be adjusted as desired for the plasma process. To that end, variable capacitors are coupled between the RF power source and the electrodes. The capacitance of the capacitors is selectively varied for varying the bias created on the substrate by at least one of the electrodes relative to the bias created on the substrate by the other of the electrodes. In that way, the effect of the plasma on one portion of the substrate relative to the effect of the plasma on another portion of the substrate may be selectively varied.
In accordance with another aspect of the present invention, at least one of the inputs to the comparators is coupled to the respective electrodes through a voltage dividing circuit. The voltage dividing circuit includes a variable resistor which may be selectively adjusted to vary the voltage level at the comparator input. When the processing system utilizes an electrostatic chuck, a DC power source is coupled to the electrodes in addition to the RF power source. The DC power source provides a voltage differential at the electrodes which is necessary for electrostatically clamping the substrate to a susceptor. The variable resistors may be selectively varied to eliminate the effect of the clamping DC bias on the electrodes at the inputs to the comparators. In that way, the outputs of the comparators are directly related to the differences between the inputs caused by the DC bias on the electrodes created by the RF power source.
In accordance with another aspect of the present invention, another comparator is utilized having first and second inputs coupled to the first and second electrodes, respectively. The output of the comparator is also reflective of the voltage difference between the first and second inputs resulting from the bias difference between the first and second electrodes. However, the output is coupled to an automatic adjustment device, such as a servo motor, which is, in turn, coupled to the variable resistor. The servo motor automatically varies the resistance of the variable resistor in order to adjust one of the inputs and to zero the output from the comparator. The output of the comparator drives the servo and the variable resistor until the output is zero. When this is done with the DC power source on and the RF power source off, the bias measurement is essentially not affected by the DC power source because the inputs to the comparator coupled to both the electrodes are adjusted to generate a zero output. Since the inputs to the comparator providing automatic adjustment of the variable resistor are the same as the inputs to the comparator which measures the different bias between the electrodes, automatically zeroing the output of the one comparator will zero the output of the other comparator as well. A disabling switch is coupled between the output of the respective comparator and the automatic adjustment device. The disabling switch is coupled to the RF power source and is operable for disabling the automatic adjustment device when the RF power is delivered to the electrodes. In that, the output of the comparator coupled to both electrodes will not be further varied to zero its output, and therefore it will measure the voltage differential between its first and second inputs to provide an output signal reflective of the bias differential between the electrodes.
Therefore, the signals are generated at the output of the comparators to be reflective of the individual bias levels of the electrodes which are attributable to the RF power supply. In that way, the variable capacitors may be adjusted to achieve the desired electrode bias between the two electrodes. Accordingly, the biasing of the substrate may be similarly selectively varied to achieve the desired results within the plasma process. While the present invention is described with respect to two electrodes, multiple electrodes may also be utilized and their bias levels measured accordingly, utilizing the present invention.
These features and benefits of the invention, and other features and benefits are set forth in greater detail in the Detailed Description hereinbelow made in reference to the drawing figures.

Method for monitoring substrate biasing during plasma processing of a substrate


A power driven wheel chair is described which includes a rear wheel support frame and at least two ground engaging rear wheels mounted in spaced relation to opposed sides of the rear wheel support frame. A front wheel support frame is pivotally secured to the rear wheel support frame for pivotal movement about a substantially horizontal axis. At least two ground engaging front wheels are mounted in spaced relation to opposed sides of the front wheel support frame. A drive motor provides motive force to at least one wheel of one of the pairs of at least two ground engaging wheels. A chair is mounted on one of the rear wheel support frame and the front wheel support frame. The wheel chair, as described, has added stability as relative pivoting of the rear wheel support frame and the front wheel support frame maintains the wheels in contact the ground at all times.

Power driven wheel chairs enable persons who must use such conveyances greater freedom of movement. This is particularly apparent in relation to use out of doors. Power driven wheel chairs can go across uneven terrain that a hand propelled wheel chair could not possibly manage.
It is difficult for a power driven wheel chair to maintain all its wheels on the ground when stepping over obstacles. When one of the front wheels of a wheel chair climbs an obstacle, it tends to lift the rear wheel on the same side. When one of the front wheels of a wheel chair descends an obstacle, it tends to lift the rear wheel on the opposite side. These tendencies adversely effect the traction of the rear wheels, and the overall stability of the wheel chair.


A process to determine malfunctioning detectors in a danger signaling system having a control center and at least two-wire signaling line joined to multiplicity of detectors. Control center emits voltage-modulated digital control and interrogation data to the detectors, and the detectors when interrogated by the control center emit current-modulated digital data to the control center; if faulty data are received following an interrogation, control center emits a voltage signal to the detectors for closing the switches of all detectors; the power input of the detectors is measured and saved in a measured-value memory; the control center subsequently provides an impressed current of a preset magnitude to the line; an evaluation device opens the switch if the power input does not exceed a preset measured value and the voltage dropping on a measuring resistor reaches a preset value; the detector next in succession also opens the switch if the voltage dropping on its measuring resistor reaches its preset value and the power input does not exceed the preset maximum to identify the malfunctioning detector.

Not Applicable
Not Applicable
The invention relates to a process and device to determine malfunctioning detectors acting as current sinks in a danger signaling system. Danger signaling systems, e.g. fire alarm installations, as a rule, include a major number of danger detectors which are connected to a two-wire signaling line. This one may be conceived as a stub-end feeder or a ring circuit via which the individual detectors communicate with a control centre. Each detector has a sensor or the like which, in dependence on parameters in its bypass, produces measured values which are transferred to the control centre through the line. In order to associate the measured values with the individual detectors, it is necessary to assign an identifier or address to each detector. This one is saved in a non-volatile memory.
From DE 196 34 099 A1, a process for the bidirectional data transfer to a bus between the control centre and the detectors has become known wherein the control centre represents the master and the detectors represent the slaves and the transfer of data sequences from the master to the slaves is effected via an impressed voltage and the slaves, while emitting signals, exhibit the behaviour of current sinks. For an increase in the coverage of transfer from the slaves to the master, a bit-synchronous process is proposed for the data transfer. The document further states that the behaviour of the bidirectional data transfer is of a direction-dependent asymmetry in transfer quality. While the transfer via an impressed voltage from the master to the slaves is effected with no damping as a consequence of the current-reducing behaviour of the slaves and, therefore, is termed to be of a high degree of quality and a low susceptibility to malfunctions and a wide coverage the transfer via an impressed current from the slaves to the master is of a lower quality. Some of the causes are that the data bits undergo significant changes due to the noise in the data transfer channel. As another cause, the capacitance per unit length for the data transfer channel is mentioned, which leads to a power division so that only a fraction of the rise in power generated by the slaves arrives at the master (control centre).
Even more disadvantageous than the aforementioned influences, which mainly can be attributed to the line parameters and can have adverse effects on the quality of data transfer, can heavy current sinks prove to be. A current sink can already be provoked by a detector which has become defective during its long-term service. In view of the huge number of fire detectors which are in continuous operation by day and night, a frequently occurring case for detectors in danger signaling systems, despite all provisions made, it cannot be prevented that an individual component fails in one of the lot of detectors at a non-foreseeable time, specifically following a long period of service. If this component should increase the current flow of the detector by an inadmissible degree in an uninfluenceable, permanent way this can have an annoying effect on the flow of data. The implications which can be imagined are differently intense and may range from the malfunction of only one detector up to the failure of the whole data traffic throughout the signaling line.
In the state of the art, there is a number of differently configured signaling systems. From EP 0 111 178 A1, it has become known to open a series switch by means of an interrogation voltage jump generated by the control centre to a first value and, after a time determined by the state of the detector, to step the series switch through to the next detector by means of another interrogation voltage jump to a second value. These electric signals which correspond to the detector states will be evaluated only within preset ranges of time in the control centre. The ranges of time therebetween are defined as malfunction bands. Signals which are within these malfunction bands cause a respective malfunction message in the control centre. The chain-like step-through also serves for a detection of a short-circuit towards the succeeding detector. The point of the short-circuit may be localized and, hence, the malfunction may be remedied rapidly. In spite of the short-circuit, the complete operating voltage is maintained in the whole signaling line. Only that portion of the signaling line in which the short-circuit exists will be switched off. This document also mentions the use of digital data for the transfer which, however, is refused because its susceptibility to malfunctions.
From DE 33 46 527 A1, a process has become known for an anti-malfunction evaluation of an alarm in a signaling line of a danger signaling system wherein signaling-line states are evaluated in a control centre by means of a window discriminator disposed in the control centre. A disturbance-variable mask-out digital device connected downstream of the window discriminator, upon appearance of the threshold signal, periodically checks over a preset period whether the threshold signal still is applied. Not until this preset time has lapsed an output signal is provided to a detector evaluation device where the test procedure is discontinued once the event disappears and is re-started once a new threshold signal is applied. The known process is unsuitable for a bidirectional digital transfer at a high data frequency.
To achieve a higher reliability of data transfer in danger signaling systems it has been known, from DE 42 12 440 A1 to dispose a transfer malfunction determining system between the control centre and the detector. The transfer of data in the known system is as follows: Emission of access data in the form of a voltage from the control centre through a first transfer line, sending back of reply data of a detector, as is determined in the access data, in the form of an electric current through a second transfer line during a reply time period in which the data sent back from the detector unit which has replied to the access data emitted by the control centre are formed from state data of the detector and check sum data which were compiled by adding the detector state data to the proper address data; the control centre adds the address data to detector state data, a determination is made as to whether a error in transfer has occurred if the data determined by this addition are not in agreement with the check sum data. The known process is intended to primarily aid in preventing a noise in the transfer lines from making itself felt as a malfunction.
From DE 25 33 382 C1, a process for the automatic allocation of detector addresses in a danger signaling system has become known. In this process, the detectors are stepped through in a chain-like manner for the purpose of address assignment wherein the value measured is determined from the delay in time up to the switch-on of the succeeding detector. The step-through is carried out by the switches which are included in the path of a supply line and exist in every detector. The detector address is determined from the value of the preceding rise in line current. Whenever an interrogation cycle begins the detectors are disconnected from the signaling line by a change in voltage.
Finally, from DE 40 38 992 C1, a process has become known for the automatic allocation of detector addresses in danger signaling systems in which each detector has a transfer device, a measured-value memory, an address memory, and a voltage measuring device as well as a switch between the wires of the signaling line. In a first phase, the control centre applies a high voltage to the line, which supplies the detectors with energy by charging a capacitor. In a second phase, a short-circuiting voltage is applied to the line, which causes all detectors the address memories of which are empty to short out the line by means of their switch. In a third phase, a measuring current is impressed into the line and the voltage which will thereby drop on the first detector with its switch closed is determined by the voltage measuring device. Its value is saved in the measured-value memory. In a fourth phase, an interrogation voltage is applied to the line, which causes the detector the measured-value memory of which is occupied, but the address memory of which is empty, to become capable of communication and to be assigned an address by the control centre, which address is saved in the address memory. This operation is repeated often enough until all detectors have been provided with addresses.
From DE 4 426 466 A1, an arrangement has become known for the operation of danger detectors in which the danger detectors are connected to a signaling loop formed as a two-wire primary line of a control centre in a danger signaling system wherein the primary line has disposed at least two disconnecting elements with a signal evaluation and control device and at least one switching element in one of the line wires. Further, limit detectors are provided which do not have an address of their own. The disconnecting elements are designed to be addressed and are disposed in the primary line in such a way that at least three line portions are formed with a respective signaling group and, therefore, a collective address is assigned to each signaling group where the collective address of the detector sounding the alarm is capable of being determined in a case of alarm.
From DE 4 322 841 C2, a danger signaling system has become known, which includes a multiplicity of detectors which are connected, via at least one multi-wire looped circuit common to several detectors, to a control centre cyclically interrogating the detectors from one interrogation end of the looped circuit. The control centre applies a line voltage, which cyclically changes for a chain synchronization of the detectors, to the interrogation end of the looped circuit. Each detector comprises line voltage monitoring means as well as a switch controlled by the line voltage monitoring means in series with one of the wires of the looped circuit wherein the switch closes with a delay following a change in the synchronisation of the line voltage and provides a signaling information pulse to the interrogation end of the looped circuit. The control centre and/or the detectors comprise line malfunction monitoring means responding to wire breakage and/or wire short-circuit of the looped circuit and the control centre interrogates the detector from the two ends of the looped circuit in case of a line malfunction. The control centre, already in the same cycle in which line malfunction monitoring means detect the line malfunction for the first time in case of an interrogation from one of the two interrogation ends, also interrogates the looped circuit from the other of the two interrogation ends. A danger signaling system of this type, in spite of a contingent line malfunction, is supposed to allow for an interrogation of all detectors with no need to extend the stretch of cycle time required therefor.
It is the object of the invention to provide a process to determine malfunctioning detectors acting as current sinks in a danger signaling system which enables to automatically identify a detector which is in a malfunction in such a way.
The invention is based on the fact that the detectors of danger signaling systems usually operate with modulated current and, hence, constitute current sinks. It is to be understood in this case that malfunctions which, in turn, cause current sinks can affect communication already when the malfunction is in the order of the amplitude of the data transferred. Thus, the inventive process is not designed to detect the short-circuit of a detector, for which purpose other, simple processes can be imagined, but to detect those detector malfunctions which mostly occur because of long-term operation and interfere with the communication of data to such an extent that their smooth transfer is no longer possible, at least from the detector to the control centre. If such a malfunction has occurred in a detector in a line it is apparent that any communication with the detectors which are arranged on the side facing away from the malfunctioning detector is no longer satisfactory or also has a malfunction.
Therefore, the inventive process is applicable in a particularly advantageous manner to transfer systems according to the master-and-slave principle. It is to be understood that other transfer systems would be usable as well as far as the detectors of the danger signaling system act as current sinks when in operation.
In the process according to one aspect of the invention, the control centre ascertains that faulty data arrive at the control centre because of an interrogation of a detector. In this case, the control centre emits a voltage signal, which preferably is a voltage-modulated data word, to the signaling line. This causes all detectors to close their switches. The recognition of the respective data word is effected via the measuring resistor and the evaluation unit, which can be constituted by a logic circuit. This one controls the switch, e.g. a FET, and closes it. This causes the signaling line to be short-circuited at the location of each the detector. Subsequently, the control centre impresses the signaling line with a preset current which, however, can only be measured on the nearest detector at hand, i.e. the first detector, via its measuring resistor. Moreover, the power input of the detector is measured. The current rating is saved in a measured-value memory and is compared to a preset maximum current. If the current measured is smaller than the maximum and the impressed current is determined via the measuring resistor the evaluation device generates an opening signal for the switch. This causes a voltage jump which can be evaluated by means of a voltage measuring device in the control centre to the effect that the first detector, as seen from the control centre, has a power input in the admissible range. When the switch is opened in the first detector there will also be a measurable voltage drop in the second detector via its measuring resistor because of the impressed current. Then, the same operation will be effected as was described for the first detector. However, if the measured current exceeds the maximum the switch will remain closed. The control centre is in a position to ascertain that no further voltage jump has been generated in the signaling line within a certain interval or a certain time. This will then be a sign indicating that there is an inadmissibly large current sink on the detector concerned, which can account for the malfunction of communication in the data traffic between the control centre and the detector.
If the signaling line exists in the shape of a ring circuit the same procedure may now be adopted from the other end of the ring circuit up to the malfunctioning detector. However, if it is an individual stub-end feeder the malfunction test described could be discontinued. However, it can also be imagined, after a preset second period, to give an instruction to open the switch to the detector the switch of which has remained closed. After this, the test procedure described can be performed up to its end or up to another detector which constitutes an inadmissible current sink.
According to an aspect of the invention, additional safety is achieved in the described process if the control centre, following the arrival of faulty data, provides the signaling line with a malfunction information which is inscribed in a malfunction memory of all detectors. Then, if the control centre gives the instruction that all switches should be closed it will be ascertained in the respective detectors whether the malfunction memory is occupied. However, the switch will be closed only if the malfunction memory is occupied.
The above-described process is applicable particularly if communication between the detector and the control centre is in a malfunction, but a transfer of data still is possible in the opposite direction. However, malfunctions can also be imagined in which data traffic is in a malfunction between the control centre and the detector and there is a suspicion that the malfunction is due to an inadmissible current sink. Another aspect of the invention sets forth how to attain the object on the assumption, however, that the supply of the detectors with the electric energy necessary for their operation is not affected. As noted previously, short-circuit incidents may also be detected in another way.
In the process according to another aspect of the invention, a detector provides a malfunction signal to a malfunction memory unless it receives an interrogation signal from the control centre within a preset interval. The operation of danger signaling systems usually is such that the individual detectors are cyclically interrogated for their state and do not arbitrarily send signals to the control centre. Therefore, it is possible, in each detector, to install a circuit which ascertains whether an interrogation has taken place within a preset period. This is easily the case for detectors which include a microprocessor and, hence, may be programmed accordingly. In such case, the detector saves a malfunction signal in its malfunction memory and, if a reply signal is not received, the control centre emits a voltage signal (a data word) by which the malfunction memories of the detectors capable of reception are occupied. This will then cause an occupation all malfunction memories of the detectors in a signaling circuit or an individual stub-end feeder and an identification of the malfunctioning detectors may commence. The control centre generates a voltage signal, e.g. by applying a certain voltage or switching off the supply voltage and switching it on again. This will be interpreted by the detectors to the effect that their switches need to be closed. The further course of the process equals the one according to the first aspect of the invention.
An advantageous circuit arrangement for a danger signaling system for the implementation of the process according to the first and second aspects of the invention is set forth here. By means of danger signaling systems in which the individual detectors exhibit the switches interconnecting the wires of a signaling line, it will also be possible to disconnect detectors acting as inadmissible current sinks from a line. So-called short-circuit disconnectors are known as such. For various reasons, the threshold value to make such short-circuit disconnectors respond cannot be chosen to be so low that malfunctioning detectors which sink an inadmissibly high current are automatically disconnected from the line. Therefore, an aspect of the invention provides that the power input of the detectors be measured and be compared to a setpoint value, in which detectors a malfunction signal is saved in the memory. The control centre may ascertain a malfunction because no reply signal is received as a detector may also ascertain its malfunction or a malfunction in the line if it has not received any interrogation signal within a cycle. If a current rating comparison reveals that the power input of a detector exceeds a preset value a short-circuit will be created between the wires of the signaling line by closing the mentioned switch. The short-circuit is maintained for a time sufficiently long to reach the response threshold value of the short-circuit disconnecting member which then will break at least one of the wires.
According to official regulations, at least 32 detectors are required to be disposed between two successive short-circuit disconnecting members. If a detector acting as an inadmissible current sink in this way is located between two short-circuit disconnecting members a response of the two adjoining disconnecting members is provoked by means of the short-circuit current generated. The capacitor which anyhow exists in the detectors serves as a source of energy for maintaining the switching functions of the detector even following the closure of the switch up to the activation of the two short-circuit disconnecting members.
If a individual stub-end feeder is installed all detectors which are located between the control centre and the first short-circuit disconnecting member opening its switch may be caused to resume the data traffic with the control centre and, hence, to assume their monitoring function. If a detector ring circuit is installed it will even be possible, in case of an incoming supply from two sides, to separate out a line portion each including the detectors interfering with the data traffic, which is located at the incoming-supply ends of the control centre or is located in the intermediate portion of the ring circuit. All line portions with intact detectors may continue to perform their functions or can be caused to do so.

Process and device to determine malfunctioning detectors acting as current sinks in a danger signaling system


A compartment for powder coating of workpieces (20) which is simple in structure, cost effective, and easy to clean comprises a floor (32, 40), two sidewalls (2, 4), and two end walls (10, 12) at least one (12) of which has a door opening (16) for entry and/or exit of the workpieces (20). Two oblique walls (22, 24) are arranged symmetrically inclined with respect to each other at the inside surfaces of the sidewalls (2, 4) in the lower corner regions of the compartment, so that, together with the corner regions, they define a suction channel (34, 36) each, and with their lower edges they form suction gaps (s). The walkable floor (32) may be embodied by a stationary plate or a discharge belt. The oblique walls (22, 24) can be tilted up against or removed from the inside surfaces of the sidewalls (2, 4) for cleaning purposes.

The instant invention relates to a compartment for powder coating of workpieces, comprising a floor, two sidewalls, two end walls at least one of which has a door opening for entry and/or exit of the workpieces, a ceiling, and a suction system outside of the compartment.
Workpieces usually are introduced into such compartments by a conveyor means and then coated with powder. Not all the powder supplied by the applicator devices to the workpieces actually deposits on the workpieces. Instead, the major part of this so-called excess powder settles on the compartment floor.
It is known to remove excess powder from the compartment by constructing the lower part of the compartment of sidewalls which are inclined in V shape with respect to each other, with a suction aperture provided at the lowest point thereof through which the powder slipping down along the oblique sidewalls is sucked off by means of a fan. As it is not possible to walk into such a compartment it is very difficult to clean it. Manual cleaning, especially of the suction channel disposed below the suction aperture practically is excluded (see for example, EP200681B1).
To overcome that, it has been proposed to design the floor of the compartment as a walkable discharge belt by which the accumulated excess powder is conveyed to a suction aperture at the end wall. Slots are provided at either side of the discharge belt outside of the two lower corner regions of the compartment and these slots communicate with lateral suction channels for recovery of the powder which a cleaning device blows off the walls of the compartment (see, for example, EP727 258B1). True, the floor constituted by the discharge belt is walkable and the walls of the compartment can be cleaned by a pneumatic cleaning device which is specifically provided for this purpose and movable through the compartment. But access to the suction channels located outside of the compartment for manual or mechanical cleaning is difficult. The discharge belt must be cleaned separately outside of the compartment. All this leads to an expensive structure.
It is an object of the invention to provide a compartment of the kind specified initially which is simple in structure, permits perfect removal of excess powder by suction and is easy to clean, including the suction channel.
A compartment according to the invention has a walkable floor embodied either by a stationary plate or a discharge belt. At least one but preferably two suction channels are integrated in the two lower corner regions of the compartment by the oblique walls according to the invention. These oblique walls preferably are hingedly connected to the inside surfaces of the sidewalls so that, for cleaning, they either can be tilted against the vertical inside surfaces of the sidewalls or removed from the same. Moreover, the pivotable connection of the oblique walls at the inside surfaces of the sidewalls permits easy adjustment of the gap widths of the suction gaps which are defined between the lower edges of the oblique walls and the floor of the compartment.
In the case of the embodiment where the floor of the compartment is a discharge belt, any remaining excess powder not sucked off laterally is conveyed out of the compartment and separately removed by suction outside of the same.
A compartment according to the invention is very cost effective due to its simple structure and the infrequent need for uncomplicated cleaning. The invention can be applied with particular advantage also where compartments are long.
Further advantageous modifications of the invention are covered by the dependent claims.

Compartment for powder coating of workpieces


Apparatus and methods for spectroscopic analysis of biological tissues to classify an individual as diabetic or non-diabetic, or to determine the probability, progression or level of a disease or medical condition in an individual.

Non-invasive devices and methods for detecting disease, such as diabetes, are described. In particular, the exemplary embodiments relate to methods and apparatuses suitable for determining in a mammal the presence, likelihood, progression and/or severity of diabetes mellitus.
Diabetes mellitus ("diabetes") is a group of metabolic diseases in which a person has high blood sugar (hyperglycemia), either because the body does not produce enough insulin, or because the body's cells do not respond to the insulin that is produced. Diabetes is a disease derived from multiple causative factors and characterized by elevated levels of plasma glucose in the fasting state or after administration of glucose during an oral glucose tolerance test (OGTT). There are two primary forms of diabetes mellitus: (1) insulin dependent or Type 1 diabetes (a.k.a., Juvenile Diabetes, Brittle Diabetes, Insulin Dependent Diabetes Mellitus (IDDM)) and (2) non-insulin-dependent or Type II diabetes (a.k.a., NIDDM). Type 1 diabetes develops most often in young people, but can appear in adults that have the same auto anti body as the Type 1. Type 2 diabetes develops most often in middle aged and older adults, but can appear in young people. This high blood sugar condition produces symptoms of polyuria (frequent urination), polydipsia (increased thirst) or polyphagia (increased hunger). Diabetes is a large and growing problem throughout the world's developed and developing nations. As of now, it has been forecasted that approximately one in 10 U.S. adults have diabetes and according to a Centers for Disease Control and Prevention report, cases of diabetes are projected to double, even triple, by 2050 with as many as one in three having the disease, primarily type 2 diabetes.
Insulin is a hormone produced in the pancreas by β-cells. The function of insulin is to regulate the amount of glucose (sugar) in the blood, which enters cells through receptors that accept insulin and allow glucose to enter. Once inside a cell, glucose can be used as fuel. Excess glucose is stored in the liver and muscles in a form called glycogen. When blood glucose levels are low, the liver releases glycogen to form glucose. Without insulin, glucose has difficulty entering cells. In persons with diabetes mellitus, the pancreas either produces no insulin, too little insulin to control blood sugar, or defective insulin. Without insulin, these symptoms progress to dehydration, resulting in low blood volume, increased pulse rate, and dry, flushed, skin. In addition, ketones accumulate in the blood faster than the body is able to eliminate them through the urine or exhaled breath. Respiration becomes rapid and shallow and breath has a fruity odor. Other symptoms indicating a progression towards diabetic ketoacidotic coma (DKA) include vomiting, stomach pains, and a decreased level of consciousness. Persons with diabetes are at increased risk for debilitating complications such as renal failure, blindness, nerve damage and vascular disease. Although risk for or progression of complications can be reduced through tight glucose control combined with drug therapy and lifestyle changes, effective mitigation of complications begins with early detection. The disease leads to serious complications, including hyperglycemia, macroangiopathy, microangiopathy, neuropathy, nephropathy and retinopathy. As a result, diabetes adversely affects the quality of life. Similarly, uncontrolled Type 2 diabetes leads to excess glucose in the blood, resulting in hyperglycemia, or high blood sugar.
A person with Type 2 diabetes experiences fatigue, increased thirst, frequent urination, dry, itchy skin, blurred vision, slow healing cuts or sores, more infections than usual, numbness and tingling in feet. Without treatment, a person with Type 2 diabetes will become dehydrated and develop a dangerously low blood volume. If Type 2 diabetes remains uncontrolled for a long period of time, more serious symptoms may result, including severe hyperglycemia (blood sugar over 600 mg) lethargy, confusion, shock, and ultimately "hyperosmolar hyperglycemic non-ketotic coma." Persistent or uncontrolled hyperglycemia is associated with increased and premature morbidity and mortality. As such, therapeutic control of glucose homeostasis, lipid metabolism, obesity, and hypertension are critically important in the clinical management and treatment of diabetes mellitus.
Pre-diabetes (i.e. where no overt clinical signs of diabetes are displayed) can be present for seven or more years before the detection of glycemic abnormalities and after disease onset and early stage diabetic complications are presented or diagnosed. More aggressive screening of individuals at risk for diabetes is needed. A major reason is that no simple and unambiguous laboratory test has existed that can be used to identify those subjects at risk for developing diabetes or pre-diabetes. There also is a need to identify subjects with a diabetic condition, including both pre-diabetic and diabetic subjects, so that they can obtain treatment early, and also to monitor the progression of the disease over time non-invasively. Early diagnosis, intensive treatment and consistent long-term follow-up evaluations for diabetic patients are essential for effective care, which can help preserve vision and significantly lower the risk of blindness. The diabetes Control and Complications Trial, (DCCT) in the USA demonstrated if a diabetic can be detected and brought under glucose control, complications can be reduced, e.g., (retinopathy) by eighty percent (80%). Once it becomes apparent that a patient may possibly develop diabetes, doctors are trained to ask the patient to return for more tests on a periodic basis to determine whether the patient's condition actually develops into the disease. Doctors have certain protocols about how long a patient should wait before being recalled for more testing. If a patient has few symptoms suggestive of diabetes, the patient may not be recalled from more than a year. If several suggestive symptoms are present, the doctor may wish to recall the patient after only a few months. Unfortunately, there is no diagnostic tool for accurately predicting how long a patient may have been experiencing diabetic symptoms, or for determining how great the patient's risk of actually developing the disease. If such a tool were available, it would enable a doctor to tailor his recall and therapy pattern to a patient's needs.
Modern diabetes screening and monitoring is a particularly "puncture-intensive" because diabetics have to draw blood to test their glucose levels. The only practical, reliable screening method currently available for monitoring blood glucose is by means of blood sampling. The primary screening and diagnostic tests currently in use—the Fasting Plasma Glucose (FPG) and the Oral Glucose Tolerance Test (OGTT)—are not considered to be optimum because they are inconvenient and unpleasant. Both require venous draws and are fasting tests so they can only be practically administered during morning appointments and are prone to non-compliance issues. For the OGTT, the measurement occurs two (2) hours after the patient ingests a 75 g oral glucose load. Numerous studies have evaluated the performance of each of these tests in diverse populations. It is believed that approximately one-half of those with diabetes are misclassified by a single FPG test. In addition, it is believed that the OGTT suffers from relatively poor reproducibility. In addition, the HbA1c test reflects longer term 90 day glycaemia and control or lack of control than FPG does, the results of the test can also be distorted due to recent changes in diet or hemolytic conditions. Such blood glucose measurement methodologies have limited value as indices of long-term glycemic status. In summary, blood glucose measurements (such as HbA1c and FPG) have limited value as reliable indices of long-term glycemic status.
Consequently, a rapid, accurate, reliable and convenient and non-invasive screening test is needed as a viable alternative to current tests. Ideally, an improved screening test would measure an analyte that is directly related to progression of the disease and the risk of complications, and the chemical marker would be invariant to within- or between-day changes in the patient as an integrated biomarker. In addition, the measurement should offer sufficient accuracy to detect diabetes in its early stages and possess adequate precision to eliminate the requirement for repeat, confirmatory testing. Once it becomes apparent that a patient may possibly have diabetes, doctors and optometrists will ask the patient to return for more tests on a periodic basis to determine whether the patient's condition actually develops into the disease or is confirmed to be diabetes. There are certain protocols about how long a patient should wait before being recalled for more testing. If a patient has few symptoms suggestive of diabetes, then the patient may not be recalled for more than a year. If several suggestive symptoms are present, then the patient may be recalled after only a few months. It would be useful if there was available a diagnostic tool and methods for non-invasively and accurately determining whether a patient is at risk of actually developing diabetes or actually has diabetes for immediate confirmation.
A major consequence of hyperglycemia is excessive glycosylation (non-enzymatic glycation) of proteins in a process known as the Maillard reaction. Excessive glycosylation eventually causes the formation of various protein-protein cross-links and non-crosslinked structures called Advanced Glycation End-products (AGEs). AGEs are believed to present an attractive candidate analyte for non-invasive measurements. AGEs have been implicated as causal factors in the complications of diabetes, including diabetic retinopathy (DR). Protein glycation is a multi-stage reaction that begins with formation of a sugar adduct to protein, known as a fructosamine or Amadori compound, which gradually matures to form AGEs. Some AGEs require oxidation chemistry for their formation and are known as glycoxidation products. Collagen is a protein that readily undergoes glycation and glycoxidation. Because of its long half-life, the level of AGEs in collagen is believed to act as a long-term integrator of overall glycemia that is insensitive to short- or intermediate-term fluctuations in glycemic control. As a result, AGEs accumulate naturally during healthy aging, but at significantly accelerated rates in persons with diabetes. Protein glycation and AGE formation are accompanied by increased free radical activity that contributes to the biomolecular damage in diabetes. Levels of AGEs are positively correlated with the severity of retinopathy, nephropathy and neuropathy and, as such are an indicator of systemic damage to protein in diabetes and a metric of a patient's risk for diabetic complications. In addition, due to the mild to severe hyperglycemia associated with pre-diabetes and type 2 diabetes, individuals who are in the early stages of this continuum will accumulate AGEs at higher than normal rates in their tissues. Thus, given sufficient assay sensitivity, an accurate AGE measurement in an individual offers the promise to detect early departure from normal glycemia. Currently, AGEs are assayed by invasive procedures requiring a biopsy specimen, and consequently are not used in diabetes screening or diagnosis.
Tissue such as the ocular lens can exhibit fluorescence when excited by a light source of a suitable wavelength. This fluorescence emission, arising from endogenous fluorophores, is an intrinsic property of the tissue and is called autofluorescence to be distinguished from fluorescent signals obtained by adding exogenous markers (like sodium fluorescein). The tissue fluorophores absorb certain wavelengths of light (excitation light), and release it again in light of longer wavelengths (emission). Several tissue fluorophores have been identified, such as collagen, elastin, lipofuscin, NADH, porphyrins and tryptophan. Each fluorophore has its characteristic excitation and emission wavelength, that enables localization and further quantification of a particular fluorophore. Autofluorescence can be induced in several tissues and can therefore be applied in investigation of several diseases. It is also used to distinguish malignant from benign tissue in several tissues, such as the skin and cervix. Furthermore, in ophthalmology, autofluorescence of the lens increases with ageing and diabetes. Autofluorescence of the lens appears to be caused by glycation and, subsequent oxidation of lens crystalline, which forms AGEs. The crystalline lens represents an exceptional bio target since the proteins in the lens are relatively static for life and do not turn over (i.e., undergo reverse glycation) allowing for the accumulation of AGEs.
Advances in fluorescence spectroscopy of the ocular lens has revealed a potential for a non-invasive device and method to sensitively measure changes in the lens of the eye associated with diabetes mellitus. The system relies on the detection of the spectrum of fluorescence emitted from a selected volume (about 1/10 mm3 to about 3 mm3 or more) of the lens of living human subjects using low power excitation illumination from monochromatic light sources. The sensitivity of this technique is based on the measurement of the fluorescence intensity in a selected region of the fluorescence spectrum and normalization of this fluorescence with respect to attenuation (scattering and absorption) of the incident excitation light. The amplitude of the unshifted Rayleigh line, measured as part of the fluorescence spectrum, is used as a measure of the attenuation of the excitation light in the lens. Using this methodology it is believed that the normalized lens fluorescence provides a more sensitive discrimination between diabetic and non-diabetic lenses than more conventional measurements of fluorescence intensity from the lens. Results from such clinical measurements could be used to describe a relationship between normalized lens fluorescence and hemoglobin A1c levels in diabetic patients.
Optical spectroscopy offers one potential avenue of early, non-invasive detection of diabetes by quantifying AGEs in the lens of the eye or other tissues. In spectroscopy, a machine fires a laser or other light on the skin or in the eye. Fluorescence spectroscopy (a.k.a. fluorometry or spectrofluorometry), is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample by detecting the presence of certain molecules by measuring their reflected or emitted light. In fluorescence spectroscopy, the species is first excited, by absorbing a photon, from its ground electronic state to one of the various vibrational states in the excited electronic state. Collisions with other molecules cause the excited molecule to lose vibrational energy until it reaches the lowest vibrational state of the excited electronic state. The molecule then drops down to one of the various vibrational levels of the ground electronic state again, emitting a photon in the process. As different molecule species may drop down from different vibrational levels to the ground state, the emitted photons will have different energies, and thus frequencies. Those photons that are reflected from particles surfaces or refracted through them are called "scattered". Scattered photons may encounter another grain or be scattered away from the surface so they may be detected and measured. Every molecule has a signature structure that reflects light at a specific wavelength; all glucose molecules share a unique signature that's entirely different from other blood components such as hemoglobin. If the returning wavelength differs from an established norm, the device alerts the patient or doctor to the presence of the molecule or cell in question. Therefore, by analyzing the different frequencies of light emitted in fluorescent spectroscopy, along with their relative intensities, the structure of the different vibrational levels can be determined.
Fluorescence-based systems rely on the propensity of certain cell components, known as fluorophores (e.g., tryptophan, flavins, collagen), to emit light when excited by specific wavelengths of light, with the peak intensity in a different, but corresponding frequency band. The actual amount of light emitted by fluorophores is exceedingly small (on the order of nanowatts) requiring an extremely sensitive photodetection system. The basic function of an optical spectroscopy device is to irradiate the specimen with a desired and specific band of wavelengths, and then to separate the much weaker emitted fluorescence from the excitation light. Only the emission light should reach the eye or detector so that the resulting fluorescent structures are superimposed with high contrast against a very dark (or black) background. The limits of detection are generally governed by the darkness of the background, and the excitation light is typically several hundred thousand to a million times brighter than the emitted fluorescence.
If AGEs are illuminated by light from 300-500 nm, then 400-700 nm fluorescence is emitted. Certain early metabolic changes may be detected by fluorescence spectroscopy as AGEs develop. Reflectance techniques attempt to characterize tissue by measuring the amount and wavelengths of light reflected back to a sensitive photodetector when the tissue (e.g., lens of the eye) is exposed to a light source. Fluorescence and reflected light measurements are analyzed using computer-based algorithms; however, these systems have not been studied extensively. Non-invasive ocular fluorescence measurements have been investigated on numerous occasions for diabetes screening and AGE quantitation.
For example, autofluorescence of the lens of the eye can be measured with a computer fluorophotometer (Fluorotron Master, Coherent Radiation Inc. (Palo Alto, Calif.)) fitted with a special lens ("anterior segment adapter") for detailed scanning of lens. Autofluorescence of the lens, excited by a beam of continuous blue light can be scanned along the optical axis by moving the internal lens system of the fluorophotometer by a computer-controlled motor. The wavelengths of excitation and fluorescent light can be set by color filters with peak transmission at 490 nm and 530 nm respectively. The measured autofluorescence, expressed in equivalents of fluorescein concentration can be recorded as a function of distance in the eye.
It is always desirable to detect diseases early in their progress. In particular, it is desirable to screen and start treating glucose-intolerant individuals as early as possible since, even before the onset of diabetes, vascular lesions gradually develop with deterioration of glucose tolerance. Additionally, beta-cell function is seriously compromised by the time that overt alterations in glucose homeostasis, such as impaired glucose tolerance (IGT) and impaired fasting glucose (IFG), are manifest; thus, timely intervention is important to maintain residual insulin secretory capacity. Early detection enables early treatment which is generally believed to yield a higher success rate in treating various diseases. Recently, it is believed that analyzing eyes, and in particular the lenses of the eyes, can yield indications of various types of diseases. For example, measurements taken of light scattering within the eye has been shown to provide useful diagnostic information to detect and monitor the progress of diseases. Since this region is up to a few millimeters thick, measurements of this region, to be useful, need to be very accurate in the information for the position of the measurement. This is especially true because the human eye is in almost constant motion even when a patient is fixating on an illuminated target. This is particularly true because eye care professionals, such as optometrists, regularly examine, diagnose, treat and manage diseases, injuries, and disorders of the eyes and associated structures, as well as identify related systemic conditions affecting the eye. Optometrists, through their clinical education and experience, and broad geographic distribution, and the means to provide primary eye and vision care for the public. There often the first healthcare practitioners to examine patients with undiagnosed diabetes or ocular manifestations of diabetes.
The effectiveness of early intervention with lifestyle modification or medication in arresting disease progression has been demonstrated by the Diabetes Prevention Program (Diabetes Prevention Program Research Group. NEJM 346:393-403, 2002). However, the determination of IGT and IFG is itself an issue due to the relatively invasive nature of these assessments, particularly that of IGT by an oral glucose tolerance test (OGTT). In addition, an important additional diagnostic problem is monitoring of glucose homeostasis for confirming diabetes. Compliance with glucose monitoring is poor because of the pain and inconvenience of conventional blood collection using lancets. Furthermore, non-invasive monitoring techniques for diabetes, and to determine the efficacy of therapy, are desirable. Finally, assessment of progression of frank diabetes to complications is only feasible after complications are well established. Thus, it would be beneficial to have methods for assessing the development of diabetes from pre-diabetes, and for monitoring the course of the disease.
There is known at least one attempt to produce a commercial grade non-invasive diabetes detection/screening device that measures crystalline lens fluorescence, known as the Accu-Chek D-Tector. The Accu-Chek-D-Tector is essentially a confocal microscope in that it uses confocal optics to measure AGEs to check for early signs of uncontrollable blood sugar levels and type 2 diabetes because they build up more quickly in the eyes of individuals with high blood sugar levels than in the eyes of individuals with normal levels. The device employs so called biophotonic technology and detects diabetes by shining a blue light into the lens of the eye of a patient. The returned light is collected and analyzed. The light emitted from the eye of a person with diabetes is more intense than that of a person without diabetes. In particular, a laser beam passes through a light source aperture and then is focused by an objective lens into a small (ideally diffraction limited) focal volume within or on the surface of a patient's eye. Scattered and reflected laser light as well as any fluorescent light from the illuminated spot is then re-collected by the objective lens (collector). A beam splitter separates off some portion of the light into a detection apparatus, which in fluorescence confocal microscopy may have a filter that selectively passes the fluorescent wavelengths while blocking the original excitation wavelength. After optionally passing through a pinhole, the light intensity is detected by a photodetection device (e.g., a photomultiplier tube (PMT)), transforming the light signal into an electrical one that is recorded by a computer for further analysis. In particular, the Accu-Chek D-Tector shines a blue light into the lens of the eye, then collects and analyzes the returned light.
However, major drawbacks of the Accu-Chek-D-Tector are that it is relatively slow, imprecise and costly to manufacture. Although the device could purportedly take readings in 30 seconds (15 seconds for fluorescence, 15 seconds for backscatter) to obtain a ratio of fluorescence signal to backscattered signal from a specific location within the patient's lens, the device employed a sliding filter changer to select either green (fluorescence) or blue (backscattered) light striking a photodetector via a crank mechanism. Rotation of a step motor actuated the two position slider taking one or more seconds to move from one filter to the other. In addition, in use, the patient was required to self-align to the device via a fixation system that made it difficult and time-consuming.
Most non-invasive analyzers are not designed specifically for high-throughput screening purposes. They are difficult and expensive to integrate into a high-throughput screening environment. Even after the analyzer is integrated into the high-throughput screening environment, there often are many problems, including increased probability of system failures, loss of data, time delays, and loss of costly compounds and reagents. Thus, prior non-invasive diabetes detection devices generally have not recognized the need to provide analytic flexibility and high performance.
Typically, a non-invasive apparatus uses some form of spectroscopy to acquire the signal or spectrum from the body. Spectroscopic techniques include but are not limited to Raman and Rayleigh fluorescence, as well as techniques using light from ultraviolet through the infrared [ultraviolet (200 to 400 nm), visible (400 to 700 nm), near-infrared (700 to 2500 nm or 14,286 to 4000 cm-1), and infrared (2500 to 14,285 nm or 4000 to 700 cm-1)]. It is important to note, that these techniques are distinct from the traditional invasive and alternative invasive techniques listed above in that the sample analyzed is a portion of the human body in-situ, not a biological sample acquired from the human body.
A real need exists for a versatile, sensitive, high-throughput screening apparatus and methods that can handle multiple detections and wide ranges of patients while reliably maintaining a high level of sensitivity. In addition to early identification, it there is a need for diabetes detection apparatus, devices, methods and/or systems for detecting diabetes that requires no fasting and is a cumulative test that is not exposed to variations in glucose levels caused from a variety of reasons, including food, stress certain drugs, or short term changes in diet and exercise.

Apparatus and method for non-invasively detecting diseases that affect structural properties in biological tissues


Light beams containing image information from a plurality of liquid crystal panels are converged by condensing lenses. The converged light beams are combined by dichroic mirrors and projected onto a screen by a single projecting lens. The liquid crystal panels and condensing lenses are supported by an adjusting unit, and can be moved independently, in the direction of their respective optical axes.

1. Field of the Invention
This invention concerns a projector for combining several light beams to project images on a projection surface, and in particular, an apparatus and method capable of correcting focusing error and magnification error on a projection surface.
2. Description of the Prior Art
A conventional liquid crystal color projector forms images of three primary colors on three liquid crystal panels, and the images are superimposed on a screen. In this type of liquid crystal color projector, light beams of each color are combined by means of a dichroic prism or a dichroic mirror, and the combined light beam is projected on a screen by a single projecting lens.
In such a projector, wherein images of different colors on separate liquid crystal panels are superimposed, the images of each color may not coincide properly on the screen due to assembling errors.
Such errors can be prevented by increasing the precision of each optical device in the assembly, or by correcting the errors by performing adjustments after assembling. In the former method, however, the optical devices are more costly and the assembling process is more difficult, so in general the latter method, i.e. adjustment after assembling, is employed.
The focusing error of the whole image can be corrected by adjusting the projecting lens or the screen disposed in the common part of the optical paths.
However, if there are relative focusing errors, magnification errors or other errors in the images, the optical system must be adjusted independently for each color.


The air damper includes a housing with cylindrical walls and a piston assembly reciprocating therein. The piston assembly includes an interior surface against which a seal abuts. The interior surface is textured in a grained pattern so that interstices are formed between the seal and the interior surface thereby forming an effective air passageway for damping. A cylindrical spacer spaces the interior surface from a retainer and the seal is engaged around the cylindrical spacer and between the retainer and the interior surface. An alternative embodiment inserts textile material through a damping orifice in order to vary the rate of damping.

1. Field of the Invention
The present invention pertains to air dampers with adjustable air flow rates. The adjustable air flow rates are achieved by the degree of graining or texturing of a plate which contacts the seal or by inserting a mold or assembling a media, such as a filter into a shaft or housing of the damper.
2. Description of the Prior Art
In the prior art, air dampers are known. However, typical prior art air dampers do not allow for simple adjustment of the air flow rate which controls the damping. As the damping is typically controlled by an orifice through which the air flows, such adjustment is typically done by varying the size of the orifice which requires a re-design of the air damper.
The damping rate of prior art dampers can be limited due to tooling restrictions, and tooling variations can create damping variations. Similarly, slow damping rates are difficult to achieve with prior art designs. Likewise, small variations in damping rates are difficult to achieve with prior art designs.
Examples of prior art include U.S. Pat. No. 5,603,574 entitled "Fluid Dampened Support Having Variable Stiffness and Damping", issued on Feb. 18, 1997 to Ide et al. which discloses a fluid dampened support having variable stiffness and damping. Electric discharge machining is used for the purpose of achieving fine tolerances. U.S. Pat. No. 5,697,477 entitled "Air Damper", issued on Dec. 16, 1997 to Hiramoto et al. discloses an air damper with a tapered functional damper with a plunger and a piston, and further discloses a cylindrical tapered body and an O-ring resulting in two separate chambers. U.S. Pat. No. 5,647,578 entitled "Latch Mechanism", issued on Jul. 15, 1997 to Bivens discloses a latch mechanism with an O-ring with a tapered surface. U.S. Pat. No. 4,877,155 entitled "Spill Protecting Apparatus", issued on Oct. 31, 1989 to Tull discloses an apparatus which includes an air damper which includes a seal at an open end of the cylinder and compressed gas in two chambers so that both air and friction retard or damp movement of the piston.

Air damper with adjustable air flow rate


A wafer transfer device or boat and semiconductor cleaning apparatus including a wafer transfer device and a heatable reaction core is provided. The wafer transfer device has a first unit with a plurality of first slots for receiving a first group of semiconductor wafers and a second unit with a plurality of slots for receiving a second group of semiconductor wafers. The first slots alternate with the second slots. The first unit is connectable to a first voltage source and the second unit is connectable to a second voltage source. The second voltage source is more electronegative than the first one. Typically, the first group of semiconductor wafers have impurities therein which are to be removed and the second group of semiconductor wafers are to receive the impurities. A method for protecting a plurality of semiconductor wafers includes the steps of placing the plurality of semiconductor wafers within a heatable reactor core, having a core collector electrode mounted on the outside of the heatable reactor core and having a conductive element located within the reactor core. The core collector element receives a first voltage level, and the conductive element receives a second voltage level greater than the first voltage level. A multiplicity of ions from within the reactor core are attracted to the outside of the reactor core, thereby protecting the plurality of silicon wafers from possible contamination originating from the multiplicity of ions.

The steps of the production of semiconductor silicon integrated circuits must be very clean, because even small amounts of undesirable contaminating impurities can cause complete degradation or malfunction of integrated circuits. Thus, semiconductor silicon wafers must be cleaned between processing steps.
There exist many cleaning processes used in silicon semiconductor production. Wet cleaning processes usually remove contaminants from the silicon wafer surface with special chemical solutions as part of a separate production step. Dry cleaning processes usually remove contaminants by etching the contaminants from the wafer surface within some gas or gas mixture or within a plasma environment. Gettering processes utilize the tendency for contaminants to move towards special traps inside the silicon wafer (areas with a high density of such traps are called "getters") and to stay stable within the traps.
However, wet and dry cleaning processes can only remove contaminants from the silicon wafer surface. Gettering processes can be used only for some types of contaminants (such as iron, copper, nickel etc.).
European Patent Publication EP-A-0749153, assigned to the common owners of the present application, describes a cleaning method which utilizes an electric field in the presence of heat to move positively charged impurity ions from the semiconductor wafer surface and above it towards a negatively charged electrode (called the "collector").
The apparatus of European Patent Publication EP-A-0749153 is schematically illustrated in FIG. 1 to which reference is now briefly made. The electric field is created between the electrodes, one of which, labeled 10, is attached to the wafer 12 to be cleaned. The other electrode (the "collector"), labeled 14, is placed at a distance therefrom. Wafer electrode 10 is connected to a voltage source output Vb and the electrode 14 is connected to another source output Vc, where the potential Vc is more electronegative than the potential Vb. Thus, an electric field is created to move positive ions, labeled 16, from the wafer area toward the collector electrode 14, where positive ions will be absorbed (captured). Typically, the apparatus is placed in a vacuum or in presence of a gas mixture and heated to initiate ion emission from the wafer surface. EP Publication EP-A-0749153, also describes utilizing a plasma between the two electrodes 10 and 14 to strengthen the electric field over the wafer surface.


A process for the preparation of nanofilament particles of SiOx in which x is between 0.8 and 1.2, the process comprising: a step consisting of a fusion reaction between silica (SiO2) and silicon (Si), at a temperature of at least about 1410° C., to produce gaseous silicon monoxide (SiO); and a step consisting of condensation of the gaseous SiO to produce the SiOx nanofilament particles. The process may also comprising using carbon.

Ever since the beginning of work in the field of lithium-ion batteries by the Sony company during the early nineties, this type of batteries has been widely used, leading to a commercial success. Typically, the technology is based on the use of lithium insertion materials as electrode material. Specifically, cobalt oxide is used as cathode material (invented by J. B. Goodenough) and carbon-based materials (coke or graphitized carbon) are used as anode material.
Since then, lithium-ion batteries have progressively replaced Ni—Cd and Ni-MH batteries. Indeed in many electronic applications, lithium-ion batteries perform better than Ni—Cd and Ni-MH batteries. However, because the production cost of lithium-ion batteries is high and because their intrinsic stability is generally compromised under harsh conditions, only small format lithium-ion batteries have been successfully commercialized.
Today the technology is based mostly on the use of anode materials containing graphite. However, it appears that the use of such carbon-based anode imposes a 372 mAh/g limit for the specific energy capacity, with no possibility of further increase.
The use of metallic lithium as anode material has been investigated. Indeed, metallic lithium presents a high energy density and may lead to a high specific energy capacity. However, security issues are associated to the use of metallic lithium. This is due to the growth of dendrites during use. Moreover, a limit on the lifetime after many charge/discharge cycles has been noted. These disadvantages have caused researchers to look for other solutions. For example, the use of silicon (Si), tin (Sn) and their alloys as potential high capacity anode materials has been investigated.
Indeed regarding silicon, this metal allows for a reversible insertion and de-insertion of lithium ions through a reaction between silicon and lithium, 5Si+22Li→Si5Li22, which corresponds to a theoretical capacity of 4200 mAh/g. This capacity is significantly higher than the capacity for carbon-based materials. However, silicon-based anodes are unstable during cycling due to the high volume expansion of silicon (up to about 320%).
Reducing the particle size of a silicon-based anode material (use of nanoscale particles for example) leads to better cycling performance. Indeed, the use of nanoscale particles allows for the relaxation of internal mechanical constraints associated to the large volume increase [1]. A technique consists of using a material which has a nanoscale filament structure. Indeed, such structure can accommodate the deformations in the radial direction of fibers, thus avoiding pulverization of silicon and loss of electric contacts [1,2].
Another technique for decreasing the volume expansion consists of preparing an intimate mixture of silicon and an inert component that can accommodate the deformation. For example, a fine dispersion of silicon in an inactive matrix which relaxes mechanical constraints and insures electric continuity has been prepared [1,3]. Such compromise may be achieved by using a mixture of Si/SiO2, at the expense of a partial loss of silicon capacity. In this regard, the use of silicon monoxide (SiOx, with x≈1) that has been annealed, allows for a dismutation reaction, 2SiO→SiO2+Si. The amorphous phase of SiOx outside the reaction equilibrium precipitates silicon in an amorphous SiO2 matrix, which leads to a material having a theoretical capacity of 1338 mAh/g [4].
The first synthesis of SiOx was performed by Potter in 1907 [5]. Potter noted that at temperatures higher than 1000° C., a rapid reaction between silicon (Si) and silicon oxide (SiO2) occurs. He further noted that if the reaction occurs under inert atmosphere, the reaction product appears as a brown, light, very fine and voluminous powder.
SiOx is currently commercially available. It is produced at a moderately high temperature (about 1250° C.), under vacuum, according to the following reaction [6]:

An equimolar mixture of SiO2 powder and Si powder in a tube is heated, under vacuum, until a temperature of 1250° C. is reached. Gaseous SiO formed is directed to an area of the tube that is colder and is condensed. The tube is cooled, re-pressurized, and solid SiOx is recuperated. The solid SiOx is then submitted to a grinding process until the desired granulometry is reached.
The relatively low temperature of the process, about 1250° C., allows for the use of a vacuum tube made in stainless steel (retort furnace). However in return, the partial pressure of gaseous SiO in the tube is maintained at a very low level, which greatly affects the productivity of the process. A micrograph taken by a scanning electron microscope shows a typical aspect of the material (FIG. 1) through its X-ray diffraction analysis. The X-ray diffraction analysis shows the amorphous nature of the material. Indeed, no diffraction pic is observed. This is typical to amorphous SiO that has been cooled rapidly and that has not undergone any dismutation reaction.
It is known that annealing such material at a temperature higher than 900° C., under inert atmosphere, does activate the dismutation reaction of SiO, which leads to the precipitation of a very fine silicon phase in an amorphous silicon matrix [3]:

Indeed, Takami et al. [3] prepared a composite of Si, SiOx and C by dismutation of silicon monoxide and polymerization of furfurylic acid at 1000° C. They reported a reversible capacity of about 700 mAh/g for 200 cycles.
There is still a need for materials having a high energy capacity; advantageously, the capacity is reversible for a high number of cycles. Accordingly, there is also a need for processes for preparing these materials; advantageously, the process is efficient and cost-effective.
A material having a high energy capacity can be a nanometric dispersion of crystalline Si in an amorphous SiO2 matrix. Lamontagne et al. disclose a process for the preparation of such material. The process uses SiO2 fume; also the process involves uses of various catalysts [7].
Encouraged by the result obtained by Takami et al. relative to a composite of Si, SiOx and C [3], our research group took up a more close investigation of the use of SiOx as electrode material in Li-ion batteries. We have studied, respectively, the use of SiOx and SiOx mixed with graphite as anode material in lithium-ion batteries [4]. Despite the fact that the coulombic efficiency of the first charge/discharge cycle and the electronic conductivity of SiOx are low, the theoretical specific capacity of SiOx electrodes is good, 1338 mAh/g. We have considered the addition of graphite to SiOx.


A method for localizing and estimating a pose of a known object in a field of view of a vision system is described, and includes developing a processor-based model of the known object, capturing a bitmap image file including an image of the field of view including the known object, extracting features from the bitmap image file, matching the extracted features with features associated with the model of the known object, localizing an object in the bitmap image file based upon the extracted features, clustering the extracted features of the localized object, merging the clustered extracted features, detecting the known object in the field of view based upon a comparison of the merged clustered extracted features and the processor-based model of the known object, and estimating a pose of the detected known object in the field of view based upon the detecting of the known object.

Known robotic perception systems achieve desired performance and reliability by engineering specific lighting conditions, structuring viewing conditions and exploiting process configuration. They are flexible under a narrow range of conditions that work only in a subset of real-world conditions, and may breakdown with minor changes in the surrounding environment. In addition, processing speed of known systems and related techniques is not sufficient for efficient real-time processing. Turnkey commercial vision systems can be slow when introducing wider flexibility and are made to work robustly by rigorously structuring the domain. For example, processing a large field-of-view (FOV) to search for objects in unexpected orientations that occupy 5-10% of FOV may take several seconds or more. This is further compounded when searching for front/back/side views to precisely find an object location and pose. Furthermore, cost associated with structuring the surroundings for known automation solutions for robot material transfer and handling applications can be three to ten times the cost associated with the robotic device. The range of products that can be efficiently handled can be limited in known automation systems and is often restricted to just a handful of styles. Furthermore, such systems are cumbersome to retool and slow to reconfigure for a different class of products. Thus, existing automation solutions are not readily applicable in assembly operations that deal with a wide diversity of parts due to issues related to investment, operations cost, flexibility and reconfigurability.

Method for object localization and pose estimation for an object of interest


A track seek method for a disk drive system. In the seek method of the present invention, the head is moved according to the characteristics of an ideal, electronically generated signal which is independent from data read off the disk. By varying the characteristics of the ideal signal, the seek profile is controlled. The ideal signal is sampled at times specified by an error signal which is based upon data read off the disk. The movement of the head is adjusted according to the sampled signal. Since track crossings correspond to ideal signal cycles, the number of tracks crossed is determined by counting the number of cycles of the ideal signal. Consequently, the position of the head is known at all times throughout the seek, thereby maintaining the seek in a closed-loop configuration during the entire seek. When the appropriate number of tracks have been counted, the head is stopped on the destination track and the head can access data contained therein. Furthermore, the seek operation's dynamic range may be increased by extending the range of each cycle of the ideal signal to cover more than one track.

In the field of computer systems, data is typically stored on magnetic or optical disk drive systems as a series of binary bits. A "head" is used to read and write these bits off and onto a circular data disk. In the present invention, a head refers to any suitable means for either accessing data from or storing data onto a storage medium (e.g., a magnetic transducer for magnetic disk drives, a lens assembly for optical disk drives, etc.). The circular disk is rotated about a spindle.
A servomechanism is used to locate the head in reference to fixed radial locations over the disk surface. The servomechanism is also used to reposition the head from one radial location to another location. Thus, as the head is sequentially moved radially across the spinning data disk, a number of concentric or spiral rings are described. These rings, on the surfaces of which binary bits are recorded, are referred to as "tracks".
When the computer directs the disk drive to position the head on a track different from the track wherein the head is presently positioned, this is known as a "seek". Typically, the user or the computer program reads from or writes onto the disk a number of times per operation. In addition, data is frequently written onto these tracks in a random manner. Thus, a number of seeks are often required for each disk access. Since data cannot be written onto nor read from the disk during the period of the seek, it is important that the seek be completed as rapidly and efficiently as possible.
One common practice is to manufacture disks so that they are preformatted with embedded servo information. Each track is divided into sectors which contain unique header addresses. Thus, as the head is positioned over a particular sector, the disk drive can read this address to determine the current position of the head.
It is possible that the seek can be accomplished by moving the head and reading each preformatted sector address as they are encountered, in order to determine whether the head has reached the destination track. However, one major disadvantage with this seek method is that it requires a relatively long period of time for reading the header data and comparing it with the destination track number to determine whether the seek has been completed.
In the prior art, a faster seek scheme involves applying maximum acceleration to the head for an initial period of time until the seek's approximate midway point is reached and then applying maximum deceleration. This is known as open-loop operation because the head position information is not looped back to the disk drive system. By operating the disk drive servo in this type of open-loop configuration, the head is positioned close to the desired track relatively quickly.
The disadvantage is that while seeking with the tracking servo loop open, the disk drive may lose its exact location in reference to the disk's track number. Thus, towards the end of the seek, the disk drive must access the disk to re-establish the position servoing. In essence, the servo loop must be reclosed, which takes time. Based on the information read from the preformatted sector address, the head is moved with the position loop closed, until the desired track is reached.
In short, the major part of the prior art seek scheme is done as a calculated guess--the exact position is then determined, and the head is finally repositioned to the correct track in reference thereof. Even though this seek scheme is relatively quick, it requires two stages. Thus, what is needed is a direct single stage seek scheme wherein the servo positioning loop is kept closed throughout the entire seek, so that the location of the read/write head is known at all times without having to constantly check the embedded sector addresses. Thereby, the destination track can be arrived at precisely without any overshoot or undershoot.
In the prior art, the position of the head was determined by determining its initial position and counting the number of tracks which had been crossed. However, with the prior art approach, the track crossing information is read off the disk. The problem is that the track crossing signal is typically discontinuous due to noise, defects inherent in the disk itself, and errors caused by the preformatted sectors. Consequently, these discontinuities often led to erroneous track crossing readings so that the position of the head was often incorrect. This problem is exacerbated in optical disk drive systems. In optical disk drive systems, the amplitude of the track crossing signal is relatively small and tends to fluctuate, depending on the focus of the light beam. Thus, in prior art optical disk drive seek methods, the track crossing signal is unreliable.
Another disadvantage with the prior art seek method is the manner by which seek profiles are implemented. A seek profile describes the trajectory of the head. FIG. 1 shows a profile for a typical seek. Typically, a profile defines the magnitude of the velocity 10 or acceleration 11 of the head as a function of time. For example, for a 100 track seek, the head would be subjected to a high constant rate of acceleration until the approximate halfway point is reached. In the example, this corresponds to 50 tracks. The time for this is denoted by t.sub.1. With constant acceleration, the velocity 10 increases linearly. Next, the head is decelerated for a specified amount of time (from t.sub.1 to t.sub.5). The deceleration occurs in numerous steps (t.sub.2 -t.sub.5). The deceleration occurs in steps in order to minimize the mechanical resonances of the armset holding the head. The slope of velocity 10 decreases correspondingly. The velocity decreases until the head comes to a stop at t.sub.5. The head should have been moved approximately 100 tracks and should now be close to the destination track.
The velocities, accelerations, times, etc. for a given profile are predetermined based on mathematical calculations. For each seek of different length, there exists a corresponding profile. These profiles are typically stored in look-up tables which are burned into Read Only Memory (ROM) chip. For each seek, the corresponding profile must be looked up and followed. As such, one disadvantage with this scheme is that it is inflexible and requires storing an extensive look-up table. What is needed is a seek scheme having the capability of following various profiles simply by changing a few lines of software code.
Furthermore, prior art seek methods are typically limited to a dynamic range of plus-or-minus half a track. A servo position error of greater than half a track on either side of track center will typically cause the seek to fail. The reason for this failure is that the next track cycle has already started. Given that a track width can be as thin as 1.5 .mu.m, it does not take much disturbance to cause the seek to fall outside this half track dynamic range.

Track seek method utilizing an ideal signal