A printed circuit board includes a mounted a first electronic component. The printed circuit board includes a first through holes extending from a mounting surface on which the electronic component is mounted. The printed circuit board includes a second through holes extending from a surface opposite the mounting surface and aligned with the first through holes. A second electronic component may be longitudinally between the first through holes and the second through holes. The first and second through holes may be electrically connected with the second electronic component.

1. Field
The embodiments discussed herein are related to a printed circuit board having a mounted a semiconductor device thereon and mounted accessory electronic components of the semiconductor device. The electronic components may be mounted on the printed circuit board in the vicinity of the semiconductor device. However, the periphery of the semiconductor device is limited. To equip more electronic components, a method for burying the electronic components in the printed circuit board has been proposed.
FIG. 1 is a sectional diagram showing a part of a conventional printed circuit board having the electronic components mounted thereon. A printed circuit board 1 illustrated in FIG. 1 is a multilayer board, a BGA type semiconductor device 2 mounted thereon. A solder ball 20 used as an external connection electrode of the semiconductor device 2 connects to a through hole (via hole) 10 penetrating the printed circuit board 1, thereby leading the solder ball 20 to an electrode pad 15 formed on the underside of the printed circuit board.
The electrode pad 15 on the underside of the printed circuit board 1 may connect with an electrode 3a of an electronic component 3 such as a chip resistor or a chip capacitor. The electronic component 3 such as the chip resistor or the chip condenser may be located in alignment with each electrode of the semiconductor device 2. Such electronic components are often called di-electrode components. The printed circuit board 1 shown in FIG. 1 in addition is equipped with an electronic component 4 buried therein. The electronic component 4 is buried in an insulation layer of the printed circuit board 1 and an electrode 40 formed on an end of the electronic component 4 connects to the electrode (the solder ball 20) of the semiconductor device 2 with an interstitial via hole (IHV) 1c.
As shown in FIG. 1, a technique to bury the electronic component (here, an electronic component 4) in a perforation of a prepreg layer used as a bonding layer of the printed circuit board has been presented.
Typical electronic components 3 and 4 such as the chip resistor and the chip capacitor are in the elongated shape and have electrodes on both ends of their longer sides. As shown in FIG. 1, the electronic components 3 and 4 may be located so as to be parallel with their longer sides to the surface of the printed circuit board 1. Therefore, the electronic components 3 and 4 occupy more area (footprint), which limits the number of the electronic components 3 and 4 that can be mounted d on or in the printed circuit board 1.
2. Description of the Related Art
To address this problem, a technique to form through holes that are not the through holes for wiring, in the multilayer printed circuit board and insert the electronic components therein has been proposed. With this technique, the electronic components longitudinally align in the height direction of the multilayer printed circuit board so that the footprints of the electronic components will be smaller.

Printed circuit board, fabrication method and apparatus


An optical position sensing system for sensing the position of a displaceable element. An electro-optical unit outputs a modulated optical signal and a chirped rf signal. The envelope of the modulated optical signal has a phase that has a known relation to the phase of the chirped rf signal. The electro-optical unit is coupled to a light guide element and receives and transmits the modulated optical signal along an optical path for reflection off a surface of the displaceable element in order to provide a position sensing optical signal. A reference reflecting element is disposed in the optical path upstream of the displaceable element for partially reflecting the transmitted modulated optical signal in order to provide a reference optical signal. A transducing unit receives the rf signal at one input and has another input optically coupled for receiving the position sensing optical signal and the reference optical signal which have, respectively, first and second time delays with respect to the chirped rf signal. The transducing unit produces a multi-frequency electrical signal which includes first and second frequencies corresponding to the first and second time delays, respectively. A position detecting unit coupled to the output of the transducing unit processes the multi-frequency signal in order to determine a difference frequency corresponding to the difference between the first and second frequencies and representing the position of the displaceable element.

1. Field of the Invention
This invention relates generally to an apparatus and method for sensing physical phenomena and particularly to an optical position sensing system for detecting the position of one or more displaceable elements. Still more particularly, the invention relates to a high accuracy light radar, fiber optic position sensing system for use on an aircraft in order to measure positions of various moving parts of the aircraft at high rates and with short lag times.
2. Background of the Related Art
Traditionally, electrical sensors are used to measure the position of various actuators in an aircraft which are used, for example, to control the position of various aerodynamic surfaces, such as flaps, rudder, ailerons, etc. Results of these measurements are then fed back to a system flight controller which processes this information and outputs appropriate commands to control the actuators.
A typical actuator has a rod secured within an outer casing. Depending on the actuator, the rod can move back and forth a maximum distance of a few millimeters to over 50 cms. This maximum distance is often referred to as a stroke. A sensor head associated with the actuator sends a position signal representing the position of the actuator rod to a processor that calculates a position measurement. Position measurements of the rod must be fed to the flight controller at rates up to several hundred Hz, with a lag time less than 0.5 ms, and accuracies of a few hundred micrometers. Here, lag time is defined to be the time between completion of raw data collection from a sensor and transmission of a position measurement to the flight controller.
Fiber optic position sensing systems offer numerous advantages over conventional electrical sensing systems. First, they are small and lightweight. In addition, they can be made immune from electromagnetic interference (EMI) which can occur near power lines, and electromagnetic pulses (EMP) which can occur in the event of a nuclear explosion. EMI/EMP immunity is an especially important advantage for new generation aircraft which have skins made largely of composite (non-metallic, non-shielding) material. Without heavy, bulky and expensive shielding of conventional electrical sensors and control lines, these next generation aircraft can not be safely flown in areas of severe EMI/EMP. Therefore, "fly-by-light" systems or fiber optic position sensing systems have the potential to replace "fly-by-wire" systems in future aircraft.
Some fiber optic position sensing systems use digital or optical encoding techniques in order to vary the amplitude of an incident optical signal as a surface is moved. However, sensor heads for these types of sensor systems cannot be easily multiplexed and consequently cost, complexity, weight and volume of the system are increased.
Another type of fiber optic position sensor system sometimes called an optical time domain reflectometer (OTDR) uses a pulsed optical source. In particular, OTDRs measure distances to in-line fiber reflectors by estimating a round trip transit time of a light pulse from the pulsed optical source to the in-line fiber reflector and back to a detector. Both the measurement accuracy and estimation times are fundamentally limited by the amplitude and width of the light pulse. Consequently, conventional OTDRs are usually only capable of position measurement accuracies of 5 to 500 centimeters. Some OTDRs measure distances to a Fresnel reflector at a fiber end face with submillimeter accuracy using pulse widths of 50 to 100 pS. However, these OTDRs require estimation times which are orders of magnitude longer than the submillisecond lag times T.sub.Li and cannot achieve the several hundred Hz update rates R.sub.i required for aircraft position sensing applications. Finally, it can be difficult to multiplex multiple sensor heads in OTDR systems.
Still another type of fiber optic position sensor system is a coherent optical frequency domain reflectometer (COFDR). COFDRs use coherent frequency modulated (FM) optical radiation. However, optical sources used in the COFDR must have narrow line widths and therefore tend to have low output power and low reliability. Moreover, all fibers used in COFDRs must be single mode polarization preserving fibers in order to coherently optically mix returned FM optical signals with an optical local oscillator signal and consequently are difficult to install and maintain.
Another drawback of coherent FM systems is due to the large Doppler shifts which can occur. For example, a rod in an actuator can have velocities ranging up to several centimeters per second. Passive sensor heads measure the position of the rod by reflecting or scattering optical radiation from an end face of the rod. Hence, the frequency of this scattered optical radiation is Doppler shifted. Since the Doppler shift is proportional to the frequency of the optical radiation, it can be very large. For example, if the rod is moving at two centimeters per second, then the Doppler shift for optical radiation having a wavelength of 1.06 micrometers is about 38 kHz which can result in significant errors in position measurement.
One way to eliminate such errors is to utilize first an up and then a down chirp and measure two different beat or intermediate (IF) frequencies. These two beat frequencies can then be subtracted from each other thereby cancelling out the Doppler shift. However, this requires wide bandwidth detectors and filters which reduces the signal-to-noise ratio of the measurements and consequently the accuracy of the measurements. In addition, this approach requires two time periods to obtain one position measurement.
Finally, a fourth approach to fiber optic position sensing systems with passive sensor heads involves incoherent optical frequency domain reflectometry (IOFDR). IOFDR is discussed, for example, in "Performance of Integrated Source/Detector Combinations for Smart Skins Incoherent Optical Frequency Domain Reflectometry (IOFDR) Distributed Fiber Optic Sensors," by W. B. Spillman, Jr., P. L. Fuhr and B. L. Anderson, SPIE Vol. 986, Fiber Optic Smart Structures and Skins (1988). An IOFDR is shown in FIG. 6a of the Spillman reference. There the IF signal appears at the output of a mixer. The frequency of this IF signal is proportional to the time delay introduced by a white cell. However, this system is not capable of outputting position measurements at rates R.sub.i of several hundred Hz, lag times T.sub.Li under 0.5 ms and position accuracies .delta.L.sub.Si of several hundred micrometers which is required for a flight controller to control flight of an aircraft.
Other attempts have been made to implement IOFDRs. For example, "Fiber Optic Sensor Multiplexing by FMAMCW," by R. Gallay et al., Appl. Phys. 21 (1989) discloses a sensor network with three sensors L.sub.1 -L.sub.3. However, this system is also incapable of update rates R.sub.i of several hundred Hz with lag times T.sub.Li under 0.5 ms or position measurement accuracies .delta.L.sub.Si of several hundred micrometers.
Therefore, IOFDRs or frequency modulated continuous wave (FM-CW) systems have thus far been limited in their estimation of a target's position.

High accuracy optical position sensing system


A mass spectrometer is disclosed wherein the pusher electrode of a Time of Flight mass analyser is operated in conjunction with an ion gate to ensure that low mass background or matrix ions are not injected into the drift region of the mass analyser.

1. Field of the Invention
The present invention relates to a mass spectrometer.
2. Discussion of the Prior Art
A common problem with known mass spectrometers is that the largest ions in a mass spectrum may originate from chemical species (i.e. background ions) which are of no interest to the analysis. For example, the background ions may comprise solvent ions, Gas Chromatograph carrier gas ions, Chemical Ionisation reagent gas ions or air peaks from vacuum leaks. These background ions can give rise to large ion signals which unless attenuated may saturate the ion detector thereby affecting the integrity of the mass spectra produced and reducing the lifetime of the ion detector.
It is therefore desired to provide an improved mass spectrometer.


A vehicle seat includes a frame, a flexible cover, and a material that is sufficiently mounted with respect to the flexible cover such that the material resists displacement of at least part of the flexible cover with respect to the frame. The material is characterized by a first state in which the material is characterized by a first rigidity, and a second state in which the material is characterized by a second rigidity that is greater than the first rigidity. Thus, the firmness of the seat is selectively variable by causing the material to change between the first and second states. A corresponding method is also provided.

A vehicle seat typically includes foam that is compressible to conform to the contours of an occupant so that the occupant is comfortably supported. A flexible covering, such as fabric, leather, or vinyl, covers the foam and forms the outer surface of the seat. A vehicle seat is typically characterized by a lower seat portion and a seatback portion. The lower seat portion defines a generally horizontal surface to support an occupant, and the seatback portion defines a generally vertical surface to support the back of an occupant.
Certain prior art vehicle seats include pneumatic systems to control the firmness of the seat. The pneumatic systems include a bladder within the seat that is selectively pressurized with air to control the firmness of the seat. A system of pumps and valves is employed to pressurize and depressurize the bladder.


A system and method for re-serving shared content are provided. The system includes a first impression detection unit to detect a user's consumption of the shared content via the metering data; a user detection unit to detect a device associated with the user; a shared content retrieval unit to retrieve the shared content based on the user and the device; and a shared content communication unit to transmit the shared content to the detected device.

A measurement system monitors media consumption habits by a media consumer. Thus, by being cognizant of the media consumption habits, a content provider may effectively determine whether certain content displayed or presented at a specific time is effective at attracting viewership. Media consumption may refer to viewing a program, listening to an audio program, reading a web site, for example.
The measurement system may be implemented at a single source, such as a location near a television. Thus, the measurement system may be equipped with an authentication system that avails a registration for the various personnel associated with the location. The various personnel may register themselves as the media consumer presently associated with the single source.
Alternatively, the measurement system may be equipped with an automatic detection system, thereby automatically logging the presence of a viewer or viewers associated with the content being sourced from the television.
In addition to content being provided by the television, the television and other media sources may provide shared content. The shared content may include information about goods or services. The shared content may include meta information, thereby allowing the media consumer to electively access the meta information to access a web site to learn more about the goods or services associated with the shared content.
In the specific case of shared content sourced from a television, the presentation of the shared content may be static and non-interactive (i.e. no associated meta data). By static, the shared content may be fixed and not based on the viewer being served the shared content.
On the contrary, when shared content is presented via other channels, such as through personalized Internet served content, the shared content selected may be dynamic and determinate based on the user accessing the shared content.
Studies have shown that shared content may be more effective when presented multiple times to a specific user (i.e. re-served). Thus, a user being cognizant of goods or services through shared content may be more inclined to purchase the goods or services based on repeated exposure.


An outdoor shower and spigot apparatus is primarily contained within a post. A hose connector is positioned on the lower end of the post and water is supplied to a spigot and shower through a water feed pipe which is positioned within the post and connected to the hose connector. A garden hose provides water to the hose coupling and a second garden hose may be connected to the spigot. In a preferred embodiment, the post is temporarily mounted in position such that it may be easily relocated.

1. Field of the Invention
The present invention relates to an outdoor plumbing apparatus for use as a shower and spigot. More specifically, the shower and spigot are arranged in a vertical structure having a post-like appearance that can be connected to a common garden hose for supply of water.
2. Prior Art
The uses for an outdoor shower are many. For example, showering prior to or after using a swimming pool, spa, or sauna; showering after cutting the grass or performing other yard work; showering after running, jogging, or doing other exercise to cool down. What is needed is an apparatus that is durable, can withstand the weather, is easy to use, attractive, and requires no set up after initial installation. Most of the prior inventions use a spigot for supply of water but fail to replace the spigot, which is used by the apparatus. In the past there have been attempts to provide a means by which to shower outdoors. One such attempt is found in the "Dismantlable Evaporative Cooling Shower" of Viner U.S. Pat. No. 4,720,878. Another, for a "Portable Shower" of Belkir U.S. Pat. No. Des. 256,610. A hanging variety is shown in "Portable Shower/Spray Apparatus" of Landreth U.S. Pat. No. 4,934,001. Another "Outdoor Shower Apparatus" of MacLeod U.S. Pat. No. 5,365,620 shows a unit mounted to a building having hot and cold water. Others have enclosures for the shower area for example "Portable Enclosure Assembly" of Mazpule U.S. Pat. No. 5,331,778 and "Portable Shower" of Simpson U.S. Pat. No. 5,564,138 assigned to The Coleman Company, Inc. Further, some have reservoirs as in the "Portable Shower" of Hildebrand U.S. Pat. No. Des. 339,860 and "Solar Shower" of Clark U.S. Pat. No. 5,507,275 assigned to Solar Shower Partnership. There have even been showers of sorts for the specific use of children as in the "Lawn Water Shower" of Kessler U.S. Pat. No. 5,224,652 assigned to Maui Toys, Inc. and in the "Childrens Pool and Shower" of Warren U.S. Pat. No. Des. 316,737. The common beach or pool shower being permanently attached to a source of water would also be examples of previous outdoor showers.
No apparatus is known, however, for providing a means to shower outdoors using a post-like structure with plumbing therein, fixed directly to the ground which can be selectively moveable or permanent and which attaches to the common garden hose for supply of water. Nor, is there believed to be such an apparatus which allows another common garden hose to be affixed to a spigot on the same post-like structure to be used for any number of other uses, thereby creating a new location of choice for a spigot at the same time.


A bedsore treatment ointment comprises a mixture including aloe vera, arnica, eucalyptus oil, pine oil, methyl salicylate, phenol, and lanolin. The mixture is positioned on bedsores for the treatment thereof.

1. Field of the Invention
The present invention relates to bedsore remedies and more particularly pertains to a new bedsore remedy for treating bedsores and decreasing the amount of healing time for the bedsores.
2. Description of the Prior Art
The use of bedsore remedies is known in the prior art. While these devices fulfill their respective, particular objectives and requirements, the need remains for a new remedy which decreases the amount of time required to heal a bedsore and which prevents the spreading of bedsores.


In a digital image, for each pixel to be thresholded, a threshold is selected from a set of thresholds. Selection may be based on relative magnitudes of the thresholds. At least one of the thresholds may be dynamic, and one of the thresholds may be constant for at least a region of the image.

Image segmentation is a process of dividing an image into regions of interest, and includes discrimination of objects in an image from a background. Thresholding is one technique for segmentation. In bilevel thresholding, each image pixel is assigned to one of two classes according to whether its intensity (gray level or color) is greater or less than a specified threshold, resulting in a binary image. In multilevel thresholding, the entire image is thresholded multiple times, each time with a different constant threshold, resulting in multiple binary images.
One common application is optical character recognition (OCR), where image pixels are typically segmented into characters by thresholding. Consider, for example, an image of black text on a white background. A histogram of all the intensity values in the image will have two dominant peaks: one peak corresponding to the intensity value of the black text, and a second peak corresponding to the intensity value of the white background. If a threshold is set at an intensity value that is in the bottom of the valley between the two peaks, then any pixel having an intensity value darker than the threshold may be assigned to text, and any pixel having a intensity value lighter than the threshold may be assigned to background.
In the case of black text on a white background, a constant global threshold may be determined from a intensity value histogram of the entire image. However, many images of interest are more complex than just black text against a white background. For example, an image may include blocks of color (that is, the background may vary), text may overlap blocks of different colors, and text may be lighter than the local background. For complex images, the threshold may be dynamic, varying depending on the location of the pixel of interest within the image. A dynamic threshold may be dependent on intensity value data over a region of an image, or a dynamic threshold may vary from pixel to pixel. See, for example, Joan S. Weszka, "A Survey of Threshold Selection Techniques", Computer Vision, Graphics, and Image Processing 7, 259–265 (1978) and Sahoo et al., "A Survey of Thresholding Techniques", Computer Vision, Graphics, and Image Processing 41, 233–260 (1988).
Particular problems for thresholding include determination of a suitable threshold at the boundaries of objects, determination of a suitable threshold for thin objects (where there are few object intensity values in the histogram), and determination of a suitable threshold when there are areas of interest that are lighter than the background.
There is a need for improved segmentation of complex images using bilevel thresholding.

Dynamic bilevel thresholding of digital images

Hewlett-Packard Development Company, L.P.


When it is detected that a USB cable has been connected, a status of a function is discriminated. If there is no problem even if a USB enumeration is started, a USB signal is pulled up and the enumeration is started. If it is determined that trouble occurs as a function when the enumeration is started, the pull-up of the USB signal is extended and, after the trouble is solved, the USB signal is pulled up and the enumeration is started.

1. Field of the Invention
The invention relates to a printer having a USB interface and at least an interface other than the USB interface.
2. Related Background Art
The Universal Serial Bus (USB) interface which has formally been supported since Windows (registered trademark) 98 is a new interface which is substituted for conventional IEEE1284. The USB interface has the following features.                1) Devices having various functions can be connected.
(IEEE1284 is originally an interface only for use for printers.)                2) "Plug & Play" is possible.        3) Up to 127 apparatuses can be connected via a hub.
And the like.
To realize "Plug & Play", in the USB, the device has a bus termination as shown in FIG. 3.
In FIG. 3, reference numeral 300 denotes a host side and 301 indicates a function. The termination on the host 300 side has been pulled down and one of signals on the function 301 side has been pulled up. In the case of the USB fast speed function, D+ has been pulled up. In the case of the USB slow speed function, D− has been pulled up. (Note: In the USB, there are two transfer speeds of 12 Mbits and 1.5 Mbits. The function for performing the 12-Mbit transfer is called a fast speed function and the function for performing the 1.5-Mbit transfer is called a slow speed function. In the USB, the host and hub have to be able to support both of the fast speed transfer and the slow speed transfer.) Therefore, if the host 300 and the function 301 are connected by a USB cable and a power source of the function 301 is turned on, since the signal D+ or D− is pulled up, one of the signal D+ and D− on the host side is set to the high level. The host 300 detects that D+ or D− of the USB data signal has been set to the high level, thereby recognizing that the USB function has physically been connected. When the host 300 confirms that the function 301 has been connected, the host issues a command to confirm what the connected function is. When the function 301 receives the command from the host 300, the function 301 returns information of a device class or a device model name or the information of the device class and the device model name to the host 300. For example, if the function 301 is a printer, the host recognizes that the function 301 belongs to the class of the printer from the received information of the device class or the received information of the device model name and issues a command of the printer class.
If the function 301 belongs to the class of a pointing device (human interface device), the host recognizes that the function 301 is the class of the pointing device (human interface device) from the received information of the device class or the received information of the device model name and issues a command of the class of the pointing device (human interface device).
Such a process for confirming what the connected function is is called enumeration.
Although the USB has formally been supported in Windows (registered trademark) 98, there are many apparatuses which support only conventional IEEE1284 such as personal computers before the release of Windows (registered trademark) 98, apparatuses other than the personal computers, and the like. Therefore, if the printer supports both of the USB and IEEE1284 until the USB is widely spread, it benefits the user. FIG. 4 shows a constructional diagram of a printer having both of the USB and IEEE1284. In FIG. 4, in the case of printing via IEEE1284, print data and a print command which are sent from an upper apparatus are stored from an IEEE1284 cable 115 into a buffer 113 via an IEEE1284 I/F 106, a USB/IEEE selector 107, and a buffer controller 108. A CPU 101 interprets and modifies the print command and print data stored in the buffer 113 and controls in accordance with the print command in a manner such that a motor controller 110 controls a CRMotor/LFMotor (not shown) via a motor driver 112 and a print head controller 109 controls a print head 111 to output the print data. While printing, the CPU is heavily loaded with interpretation and modification of the print command and print data sent from the upper apparatus, motor control, and print head control. When the USB cable is connected and the foregoing enumeration is started during the printing, the CPU is burdened with the enumeration, so that there is a possibility of occurrence of                1) decrease in printing speed        2) impossibility of enumeration
Particularly, in the case of a printer of a low price, a cheap CPU whose processing ability is low is often used, so that such a possibility increases.

Printer, information processing apparatus, and control method of interface


A floating offshore platform, of the type having a buoyancy can disposed within a support structure, includes a can guide assembly that has at least two compliant compression pads that are configured and arranged to provide a non-linear load-versus-deflection characteristic in response to impact loads generated by the impact of the can against the guide assembly. At least one of the compression pads is substantially stiffer (less compliant) than the other pad. The pads are arranged so that the relatively soft pad absorbs the impact load before the relatively stiff pad is engaged. In one embodiment, first, second, and third compression pads are arranged vertically, the upper and lower pads being softer (more compliant) than the middle pad. In another embodiment, a first, relatively soft, compression pad coaxially surrounds a second, relatively stiff compression pad.

The present invention generally relates to floating offshore mineral exploration and production platforms and, more particularly, is concerned with a compliant guide for protecting the buoyancy cans and components of the floating offshore platform from damage from impacts that may occur as a result of hydrodynamic loads (e.g. Froude-Krylov impact forces) on the buoyancy cans.
The spacing between the buoyancy can outer wall and the contact point of the guide structure in the centerwell of a Spar type floating offshore mineral exploration and production platform has been found to be very important in determining loads on the buoyancy can. The buoyancy can will have contact points (most typically four to six), in the form of built-up wear strips. These contact points on the buoyancy can will face corresponding contact points on the guide structure. See U.S. Pat. No. 4,702,321 to Edward Horton for "Drilling, Production, and Oil Storage Caisson for Deep Water" and U.S. Pat. No. 4,740,109 to Edward Horton for "Multiple Tendon Compliant Tower Construction", both incorporated herein by reference.
Although sensitivity to gap size had previously been noticed in both model tests and in some calculations, efforts to determine the optimum gap size had assumed that once a small enough gap had been achieved, the nature and magnitude of the loads, including impact loads, would converge to those of a zero gap. Efforts were aimed at finding the point of diminishing returns on an exponential-type either load or bending moment response curve, where forces were determined without consideration for impact loads.


The apparatus for positioning electronic components on a printed circuit board or the like includes an optical system which allows to line-up the underside of the electronic component with the intended placement position on the circuit board. After proper positioning the circuit board relative the electronic component the later is placed on the circuit board and connected therewith.

The invention relates to means for positioning of electronic components on printed wiring boards. More specifically, the invention relates to an apparatus for precision positioning of individual electronic components on printed wiring boards.
FIG. 8 is an illustration of the optical path and functional principle of a known fine placement apparatus using a video camera for observing placement of a component on a component carrier. Component 100 which is to be placed on a component carrier 101 is held in a component fixture 102 at the end of a placement rod 103. Placement rod 103 can be moved in a direction normal to component carrier 101. Rod 103 moved through opening 104 in mirror 105. The movement of rod 103 allows to load a component 100 on to fixture 102 of rod 103. Rod 103 is then lowered towards component carrier 101. The image of the top side of component 100 and the placement area surrounding on component carrier 101 around component 100 is mirrored by mirror 105 onto a dual mirror 106, where the image is reflected into the optic of vertical camera 107. This arrangement can only match the leads of component 100 with the foot print pads on component carrier 101 as far as these pads are not covered by the terminals of component 100. In a version for placing large components mirror 106 is implemented as dual mirror with the common edge of the two partial mirrors 108a and 108b being turned 45 degree relative to the projected image of component 100. In this arrangement component 100 is out of focus until it is just above the placement location. The placement location on component carrier 101 is covered by component 100 until the same is close to the placement location. At this time component carrier 101 has to be positioned so that the terminals of components 100 match the foot print pattern of the placement location on component carrier 101. The placement of components with terminals underneath the package provides additional difficulties, because none of these terminals are visible during the placement process.
The German Patent DD 242 320 discloses an apparatus for positioning of electronic components having a large number of terminals, especially surface mount components on printed wiring boards. In this publication the printed wiring board is mounted on an x-y table and the component is held by vacuum on the holding fixture of a pivoted placement arm. The under side of the component and the top surface of the printed circuit board are illuminated by a light source. A semi reflective optical mirror provides a combined real image of the component and the position at which the placement arm could position the component. The combined images can be observed through a microscope. By proper positioning of the printed circuit board using the controls of the x-y table the image of the desired positioning location for the component on the printed circuit board and the under side of the component held in the holding fixture of the positioning arm are matched. Without further change in the position of the printed circuit board the positioning arm is lowered onto the printed circuit board placing the component in the desired position. Releasing the vacuum allows to lift the positioning arm away from the component.
While this apparatus functions satisfactorily the arrangement of optical components and positioning arm is complex. It was discovered that positioning was not always as precise as expected despite proper adjustment of the images of the desired position on the printed circuit board and the electronic component.
With increased size of the components it became apparent, that a new method had to be found for matching the images of the desired position on the printed circuit board and the electronic component. It was not anymore feasible to use the complete image of the component. Furthermore, observing the images through a microscope was rather strenuous to the observing eye.
By projecting the images onto a video camera the images are observable on a display monitor. The problem of this method is the low resolution of the camera or the display monitor; the large number of the narrowly spaced leads of the component interferes with the display lines making precise matching of the images of the component difficult.

Apparatus for the positioning of components on a printed circuit board or the like


A light exposure system is for exposure of a pattern on a first object to form an image thereof on a second object, which comprises an illumination optical system for illuminating the first object, a projection optical system for projecting the pattern on the first object onto the second object, a stage device for two-dimensionally moving the second object while holding the second object, a reference member mounted on the stage device, a detecting device for detecting light from the reference member, and a measuring device for carrying out a predetermined measurement, based on an output of the detecting device. In the light exposure system, the illumination optical system comprises a light source device for supplying exposure light, an off-center multiple beam producing device for producing from the exposure light from the light source device a plurality of light sources eccentric to an optical axis of the illumination optical system, and a light condensing optical system for condensing a plurality of beams from the off-center multiple beam producing device to illuminate the first object in an oblique direction. Further in the system, the detecting device is disposed at a position where the plurality of eccentric beams are formed by the off-center multiple beam producing device and on the optical axis of the illumination optical system to receive the light from the reference member through the projection optical system and the light condensing optical system.

1. Field of the Invention
The present invention relates to a light exposure system suitable for production of semiconductors, and more particularly, to a light exposure system provided with an oblique illumination optical system illuminating in an oblique direction a projection original plate on which a circuit pattern or the like is formed.
2. Related Background Art
First prior art
Semiconductor integrated circuits have been increasing the degree of integration these days so that a minimum line width in a circuit comes to be of submicron order. With the increase of integration degree, projection exposure systems for producing semiconductor integrated circuits in the photolithography process are now required to have a higher resolution and a higher alignment accuracy. Positioning or alignment includes wafer alignment for aligning a position to be exposed for each shot on a wafer with a position where an image of a pattern of a reticle is projected to form an image thereto on the wafer, and reticle alignment for maintaining a positional relation in a certain state between the reticle and a stage upon exchange of reticle.
FIG. 6 shows a projection exposure system provided with a measurement optical system for performing the conventional reticle alignment. In FIG. 6, reference numeral 1 designates a light source such as a mercury lamp. Exposure light IL radiated from the light source 1 is condensed by an elliptic mirror 2 and then reflected by a bending mirror 3. Then, the light IL passes through an input lens 4 to become a parallel beam. The parallel beam enters an optical integrator 5 composed of a fly eye lens. A shutter 6 is located at the vicinity of the secondary focus of the elliptic mirror 2. The exposure light IL may be intercepted on demand by rotating the shutter 6 through a drive motor 7.
When the exposure light IL is intercepted by the shutter 6, the exposure light IL is reflected by the shutter 6 in a direction substantially normal to the optical axis of the elliptic mirror 2. The thus-reflected exposure light IL is made by a condenser lens 8 to enter an end of a light guide 9. The exposure light IL radiated from the light source IL enters either the optical integrator 5 or the light guide 9, accordingly.
When the exposure light IL enters the optical integrator 5, numerous secondary light source images, as will be hereinafter referred to as "secondary light source", are formed on a focal plane of the optical integrator 5 on the reticle side. A variable aperture stop 10 is positioned at the secondary light source formation plane. The exposure light emitted from the secondary light source passes through a half mirror 11 inclined at 45 degrees to the optical axis of the exposure light. Then the exposure light passes through a first condenser lens 12, a bending mirror 13, and a second condenser lens 14 then to illuminate at a uniform illuminance a pattern area on the lower surface of a reticle R.
In FIG. 6, PL represents a double side (or one side) telecentric projection optical system and 17 does a wafer stage. A wafer W is placed in a wafer holder on the wafer stage 17. The wafer stage 17 is comprised of an X-Y stage, which can two-dimensionally move in a plane normal to the optical axis of the projection optical system PL, and a Z stage, which can move in the direction of the optical axis of the projection optical system PL. An image of the pattern on the reticle R is formed by the projection optical system PL on the wafer W during exposure. In this arrangement, the secondary light source formation plane of the optical integrator 5 is conjugate with a pupil plane of the projection optical system PL. The .sigma. value, which represents the coherency of the illumination optical system illuminating the reticle R, may be changed by adjusting an aperture of the variable aperture stop 10 located at the secondary light source formation plane. Defining the maximum incident angle of the exposure light IL illuminating the reticle R as .theta..sub.IL and a half angular aperture of the projection optical system PL on the side of the reticle R as .theta..sub.PL, the .sigma. value may be expressed by sin .theta..sub.IL / sin .theta..sub.PL. The .sigma. value is set at about 0.3 to 0.6 in general.
An adjustment plate 19, which is a glass plate for example, is fixed near the wafer holder on the wafer stage 17. A reference pattern is formed on a plane of the adjustment plate 19 on the side of the projection optical system PL. Corresponding to the reference pattern, a reticle mark RM is formed in an image field of the projection optical system and in the proximity of the pattern area on the reticle R at a position where the reticle mark is conjugate with the reference pattern on the adjustment plate 19 with respect to the projection optical system PL. For example, the reference pattern on the adjustment plate 19 may be a cross aperture pattern formed in a light shielding surface, while the reticle mark RM on the wafer W may be a pattern obtained by multiplying the reference pattern by a projection magnification of the projection optical system PL and then reversing bright and dark portions in the pattern.
There are a condenser lens 21 and a bending mirror 20 placed below the adjustment plate 19 of the wafer stage 17. The other end of the light guide 9 is fixed at the rear focal plane of the condenser lens 21. A surface of the other end of the light guide 9 is conjugate with a pupil plane of the projection optical system PL, and, therefore, with the variable aperture stop 10. A light emission plane of the other end of the light guide 9 is so sized as to provide a projection image onto the variable aperture stop 10, which is substantially equal to the aperture of the variable aperture stop 10. In this arrangement, the emission plane illuminates the reference pattern on the adjustment plate 19 with an illumination .sigma. value almost equal to that for exposure light IL. Further, in the illumination optical system for exposure light IL, a light receiving portion of a photomultiplier 22 is located at a position conjugate with the variable aperture stop 10 with respect to the half mirror 11. Namely, the light receiving portion of the photomultiplier 22 is positioned in a plane conjugate with the pupil plane of the projection optical system PL and with the emission plane of the other end of the light guide 9. A detection surface in the light receiving portion is larger than an image of the light emission plane of the other end of the light guide 9 projected thereon, whereby preventing a loss in quantity of light. Consequently, when the reference pattern of the adjustment plate 19 is illuminated from the bottom side, most of light emitted through the reference pattern of the adjustment plate 19 enters the projection optical system PL and then reaches through the reticle mark RM on the reticle R to the light receiving surface of the photomultiplier 22 no matter where the adjustment plate 19 is situated in the image field of the projection optical system PL.
In FIG. 6, numeral 23 denotes a central processing unit (CPU) for controlling an operation for reticle alignment. Photoelectrical conversion signals are output from the photomultiplier 22 to the CPU 23. There are an X direction mirror and an unrepresented Y direction mirror fixed on the upper surface of the wafer stage 17. A coordinate of a position may be always monitored on the wafer stage 17 by using a laser interferometer 24 and the two mirrors. Coordinate information of the wafer stage 17 is supplied from the laser interferometer 24 to the CPU 23, and the CPU 23 may move the wafer stage 17 through the stage driving unit 25 to a desired coordinate position.
In reticle alignment, the CPU 23 makes the shutter 6 intercept the exposure light IL through the drive motor 7 and makes the adjustment plate 19 on the wafer stage 17 move into the image field of the projection optical system PL through the stage driving unit 25. By this, the exposure light IL reflected by the shutter 6 passes through the condenser lens 8 and the light guide 9 to be emitted into the inside of the wafer stage 17. The exposure light thus emitted will be hereinafter referred to as illumination light. The illumination light is reflected by the bending mirror 20 and thereafter converted by the condenser lens 21 into a parallel beam to illuminate the reference pattern formed on the adjustment plate 19 from the bottom side thereof. A zeroth order beam directly transmitted through the reference pattern of the adjustment plate 19 and illumination light diffracted by the reference pattern are converged by the projection optical system PL at the position conjugate with the reference pattern on the reticle R to form projection images of the reference pattern there.
Out of the light beams forming the projection images of the reference pattern, beams of the illumination light having passed through a light transmissive area of the reticle mark RM on the reticle R pass through the second condenser lens 14, the bending mirror 13, the first condenser lens 12, and the half mirror 13 to enter the light receiving surface of the photomultiplier 22. The higher order diffracted light beams, out of the beams of the illumination light output from the reference pattern of the adjustment plate 19 toward the projection optical system PL, are slant at large angles to the optical axis of the second condenser lens 14 when passing through the reticle mark RM of the reticle R. Consequently, most of the higher order diffracted light beams from the adjustment plate 19 do not reach the light receiving surface of the photomultiplier 22. However, the light intensity of the higher order diffracted light is very low. Therefore, as far as the adjustment plate 19 is present in the image field of the projection optical system PL, most of the illumination light from the adjustment plate 19 enters the light receiving surface of the photomultiplier, whereby the SN ratio of the photoelectric conversion signals is high enough.
The CPU 23 controls the stage driving unit 25 to scan the wafer stage 17 by the laser interferometer 24 in a plane normal to the optical axis of the projection optical system PL while monitoring coordinate information thereof. When the projection image of the reference pattern of the adjustment plate 19 on the wafer stage 17 is superimposed on the reticle mark RM, which has the pattern with inverted bright and dark portions to the reference pattern, the minimum output is obtained in a photoelectric conversion signal of the photomultiplier 22 supplied to the CPU 23. Therefore, a coordinate of the stage where the minimum output is obtained in the photoelectric conversion signal corresponds to the position where the projection image of the reference pattern of the adjustment plate 19 is superimposed on the reticle mark RM on the bottom surface of the reticle R. Then, measuring stage coordinate values of crosses RM disposed at at least two positions near the pattern area of the reticle R, a coordinate of the center position and a rotation angle of the projection image of the reticle R projected onto the upper surface of the wafer stage 17 may be measured at high accuracy. For example, the reticle R is finely moved by the reticle driving mechanism (not shown) under control of the CPU 23 in the plane normal to the optical axis of the projection optical system PL, and the center position and the rotation angle in the horizontal plane of the projection image of the reticle R are set on the upper surface of the wafer stage 17 in desired conditions, whereby effecting the alignment of the reticle R.
Next explained with reference to FIG. 7A and FIG. 7B is the fundamental structure of the conventional illumination optical system for exposure light IL. FIG. 7A simplifies the main part of the illumination optical system of the projection exposure system as shown in FIG. 6. In FIG. 7A reference numeral 26 designates a condenser lens, and the exposure light passes through the optical integrator 5 comprised of the fly eye lens, the variable aperture stop 10, and the condenser lens 26 to illuminate the pattern 15a on the reticle R. The variable aperture stop 10 is located at the reticle side focal plane P1 of the optical integrator 5, that is, at or near the Fourier transform plane to the pattern 15a of the reticle, and has an aperture 10a of substantial circle with the center at the optical axis AX of the projection optical system PL, as shown in FIG. 7B. The variable aperture stop 10 defines a circular circumference of the numerous images in the secondary light source formed on the reticle side focal plane P1.
A part of the exposure light with a wavelength .lambda. illuminating the reticle R is diffracted by the pattern 15a of the reticle R, and a zeroth order light beam D.sub.o, a positive (+) first order diffracted light beam D.sub.p, and a negative (-) first order diffracted light beam D.sub.m are incident from the pattern 15a into the projection optical system PL. These zeroth order light beam and .+-. first order diffracted light beams are condensed by the projection optical system PL onto the wafer W to form interference fringes on the wafer W. In this case, defining the pupil plane of the projection optical system PL as P2, the higher order diffracted light beams become apart from the optical axis on the pupil plane P2 with an increase of the order. If at least .+-. first order light beams could pass through the pupil plane P2, a pattern would be formed on the wafer W at a pitch obtained by multiplying a pitch P of the pattern 15a of the reticle R by the projection magnification. When a numerical aperture of the projection optical system PL on the side of the reticle R is defined as NA.sub.R, the minimum resolution limit of the pattern 15a of the reticle R, which can be resolved by the projection optical system PL, is .lambda./NA.sub.R.
The minimum pattern size is a half of the minimum pitch P, that is, 0.5.multidot..lambda./NA.sub.R. In an actual application, influences should be considered for example from the wafer warp and the photo resist in photolithography process. A practical minimum pattern size on the reticle R is k.multidot..lambda./NA.sub.R, where k is a process factor of about 0.6 to 0.8. Further, when the numerical aperture of the projection optical system PL on the side of the wafer W is defined as NA.sub.W, a depth of focus of the projection optical system PL is represented by .+-..lambda./{2(NA.sub.W).sup.2 }, and there stands such a relation that NA.sub.W =NA.sub.R /.beta., where .beta. is an imaging magnification (reduction ratio) of the projection optical system PL. Accordingly, as the numerical aperture of the projection optical system PL is increased in order to decrease the minimum pattern size on the reticle, the depth of focus becomes shallower in proportion to the inverse square of the numerical aperture.
It is a recent need that a reticle pattern with a further smaller pattern size be replicated on a wafer in order to obtain a semiconductor integrated circuit further highly integrated. There is, however, a disadvantage of a too shallow depth of focus resulted, if the minimum pattern size is reduced by increasing the numerical aperture of the projection optical system 16 in the illumination method in which the reticle R is illuminated through the condenser lens 26 with the exposure light from the secondary light source formed by the optical integrator 5 disposed on the optical axis as shown in FIG. 7A.
There is so-called plural oblique illumination proposed as shown in FIG. 8 as an illumination method for high resolution, by which the minimum pattern size may be made smaller with an acceptable reduction of the depth of focus. In FIG. 8, reference numerals 29a and 29b represent a first group of fly eye lenses (first optical integrators), and 27a and 27b a second group of fly eye lenses (second optical integrators) placed along an extension of the first group of fly eye lenses so that the second group of fly eye lenses 27a and 27b are illuminated by the exposure light emitted from the light source IL.
The exposure light beams output from the second group of fly eye lenses 27a and 27b are condensed by the guide optical systems 28a and 28b, respectively, then to uniformly illuminate the first group of fly eye lenses 29a and 29b. Variable aperture stops 30a and 30b are positioned on the reticle side focal plane P1 of the first group of fly eye lenses 29a and 29b, respectively. The variable aperture stops 30a and 30b define outer diameters of secondary light sources formed on the reticle side focal plane P1 of the first group of fly eye lenses 29a and 29b. The exposure light output from the variable aperture stops 30a and 30b uniformly illuminates the pattern 15a of the reticle R through the condenser lens 26. Since the first and second groups of fly eye lenses make the illuminance distribution uniform, uniformity of the illuminance distribution of the exposure light becomes remarkably excellent on the reticle R.
In this arrangement, the variable aperture stops 30a and 30b are disposed on the object side focal plane of the condenser lens 26, the reticle R is located on the image side focal plane of the condenser lens 26, and the secondary light source formation plane P1 is conjugate with the pupil plane P2 of the projection optical system PL. The exposure light output from the variable aperture stop 30a is refracted by the condenser lens 26 such that a ray leaving the center of the variable aperture stop (as will be referred to as "principal ray") enters the reticle R as inclined at an angle .phi.(0<.phi.<.pi./2) in the clockwise direction with respect to the optical axis AX of the projection optical system PL. In contrast, the exposure light output from the variable aperture stop 30b is refracted by the condenser lens 26 such that a principal ray enters the reticle R as inclined at an angle .phi. in the counterclockwise direction with respect to the optical axis AX of the projection optical system PL.
Supposing the reticle pattern 15a has a grating pattern formed at a predetermined pitch P in a direction parallel to the sheet plane of FIG. 8 and when the exposure light output from the variable aperture stop 30a is incident into the reticle pattern 15a, the zeroth order beam D.sub.o goes out thereof toward the projection optical system PL in the same direction as the incident light. The + first order diffracted light beam D.sub.p goes out in a direction which is inclined at an angle of (.theta..sub.p +.phi.) in the clockwise direction to the optical axis AX, while the--first order diffracted light beam D.sub.m goes out in a direction which is inclined at an angle of (.theta..sub.m -.phi.) in the counterclockwise direction to the optical axis AX. These diffraction angles .theta..sub.p and .theta..sub.m may be expressed by the following equations. EQU sin (.theta..sub.p +.phi.)-sin .phi.=.lambda./P (1) EQU sin (.theta..sub.m -.phi.)+sin .phi.=.lambda./P (2)
As the reticle pattern 15a becomes finer, the + first order diffracted light beam D.sub.p, which is output in the direction inclined by the angle (.theta..sub.p +.phi.), comes to fail to pass through the aperture stop on the pupil plane P2 of the projection optical system PL. In such a case, however, the--first order diffracted light beam D.sub.m may pass through the aperture stop of the projection optical system PL. Then, there are interference fringes made by the two beams of the zeroth order light beam D.sub.o and the--first order diffracted light beam D.sub.m on the wafer W. The interference fringes show an image of the reticle pattern 15a. If the reticle pattern 15a has a line and space pattern of 1:1, an image of the reticle pattern 15a is formed at a contrast of about 90% on a resist coating on the wafer W.
In this case, a resolution limit is set when following condition is established. EQU sin (.theta..sub.m -.phi.)=NA.sub.R ( 3)
Putting the equation (3) into the equation (2), the following relation stands with the pitch P of the minimum pattern which can be replicated, on the reticle side. EQU NA.sub.R +sin .phi.=.lambda./P
Arranging the above relation, the pitch P of the minimum pattern is obtained as follows. EQU P=.lambda./(NA.sub.R +sin .phi.) (4)
For example, if the numerical aperture, sin .phi., for the inclination angle .phi. of the exposure light illuminating the reticle R is set to 0.5.times.NA.sub.R, the pitch P of the minimum pattern is obtained as follows. EQU P=.lambda./(NA.sub.R +0.5NA.sub.R)=2.lambda./(3NA.sub.R) (5)
Comparing to the resolution limit of .lambda./NA.sub.R in the illumination method of FIGS. 7A and 7B, the illumination method of FIG. 8 can provide a higher resolution as shown.
The following discussion is about the depth of focus. If a deviation amount (defocus amount) of the wafer W from the focus position of the projection optical system PL is .DELTA.F and an incidence angle at which the zeroth order beam or a diffracted beam is incident at a point on the wafer W is .theta..sub.D, the wavefront aberration due to the defocus is given by .DELTA.F.multidot.sin.sup.2 .theta..sub.D /2. In this aberration, sin .theta..sub.D represents a distance of the diffracted light to the optical axis AX on the pupil plane P2 of the projection optical system PL. In the conventional illumination method as shown in FIGS. 7A and 7B, sin .theta..sub.D =0 for the zeroth order light beam D.sub.o. On the other hand, sin .theta..sub.D =M.multidot..lambda./P for the .+-. first order diffracted light beams D.sub.p, D.sub.m, where M is the magnification (enlargement ratio) of the projection optical system. Therefore, the wavefront aberration due to the defocus with the zeroth order light D.sub.o and the .+-. first order diffracted light beams D.sub.p, D.sub.m is .DELTA.F.multidot.M.sup.2 (.lambda./P).sup.2 /2.
In contrast, sin .theta..sub.D =M.multidot.sin .phi. in the illumination method of FIG. 8, since the zeroth order beam D.sub.o is inclined at the angle .phi. to the optical axis AX. As for the--first order diffracted light beam D.sub.m, sin .theta..sub.D =M.multidot.sin (.theta..sub.m -.phi.). In this case, if the diffraction angle .theta..sub.m is about 2.phi., sin .phi..perspectiveto.sin (.theta..sub.m -.phi.), whereby the relative wavefront aberration due to the defocus becomes almost equal to 0 between the zeroth order light beam D.sub.o and the--first order diffracted light beam D.sub.m. Then, even if the wafer W is slightly deviated in the direction of the optical axis from the focus position, the image of the reticle pattern 15a is not affected so much as to the focus condition thereof as compared to the conventional method, resulting in enlarging the depth of focus. In order to set the diffraction angle .theta..sub.m to 2.phi., the incident angle .phi. of the exposure light into the reticle R should be set to satisfy the relation sin .phi.=.lambda./(2P), as seen from the equation (2). By this, the depth of focus may be greatly increased.
Problems in the first prior art
In the plural oblique illumination as shown in FIG. 8, the .sigma. value is for example about 0.2 for the exposure light output from each of the fly eye lenses 29a and 29b, but the process is substantially equivalent to what the condenser lens 26 processes the exposure light from a light source having a circular circumference circumscribing the fly eye lenses 29a and 29b. Thus, the condenser lens 26 has to illuminate the reticle R with an illumination beam having a large .sigma. value for example of about 1, and the requirements accuracy thereof has been increasing higher and higher these days. In detail, the condenser lens 26 has to be designed to have improved illuminance uniformity and illumination telecentricity by using a beam having a large .sigma. value, which forces a great load on the design of such a condenser lens.
In addition, in order to provide the exposure system with the measurement optical system for reticle alignment, the half mirror 11 must be located between the condenser lens, which is the condenser lens 12 or 14 in the example of FIG. 6, and the optical integrator (or the variable aperture stop), as shown in FIG. 6. However, if a beam for reticle position measurement is taken out by placing a half mirror in an optical axis between the condenser lens 26 and the optical integrator or the variable aperture stop, as being the case in the conventional method, in the illumination method as shown in FIG. 8, the condenser lens 26 would be doubled in outer diameter as compared to that in the conventional method, which disadvantageously increases difficulties in designing and in production.
Further, if the half mirror 11 is placed between the condenser lens 12 and the optical integrator 5 as shown in FIG. 6, the throughput is extremely lowered with a decrease in power of the exposure light due to a loss in quantity of light. If the reflectance of the half mirror 11 is restricted in order to solve the problem of the light quantity loss, the detection accuracy would be greatly lowered with a decrease of receiving light quantity of the detection system such as the photomultiplier 22. Moreover, a flare could be caused depending upon the arrangement of the half mirror 11, which results in illuminance unevenness on the wafer and measurement errors in reticle alignment.
A so-called annular zone illumination method, in which the reticle is illuminated by a secondary light source formed in annular zone by the optical integrator, may be also employed to illuminate the reticle in the oblique direction in the same manner as in the above plural oblique illumination method, while improving the resolution and the depth of focus of the projection optical system.
In the annular zone illumination method, the reticle is obliquely illuminated in the same manner as in the plural oblique illumination method. The annular zone illumination method could be considered as one of the oblique illumination methods, and, therefore, the annular zone illumination method and the plural oblique illumination method will be hereinafter generally referred to as an oblique illumination method.
However, if the half mirror 11 is placed between the condenser lens 12 and the optical integrator 5 as shown in FIG. 6, there would be problems caused in designing and in production of the condenser lens 26 as well as problems of illuminance unevenness due to the light quantity loss, the flare, and the like and of measurement errors, similarly as described.
Second prior art
A reduction projection exposure system is used to replicate a pattern of a reticle through a projection optical system onto a wafer in production of semiconductor devices or liquid crystal display devices with use of the photolithography technique. One of important properties of such a projection exposure system is the overlay accuracy. A main factor giving an influence to the overlay accuracy is a magnification error of the projection optical system. A line width in a pattern, which is used for very large scale integrated circuit (VLSI) for example, becomes finer and finer with years, and a need to improve the overlay accuracy on the wafer becomes greater accordingly. There is then another need for keeping the projection magnification of the projection optical system within a certain range.
It is known that the projection magnification of the projection optical system fluctuates in the vicinity of a desired magnification because of a slight temperature change in the system, a slight pressure change in atmosphere in a clean room, a temperature change of atmosphere, and irradiation hysteresis of exposure light on the projection optical system. Some of conventional projection exposure systems have a magnification correction mechanism for finely adjusting the magnification of the projection optical system to obtain a desired magnification. Examples of such a magnification correction mechanism are a mechanism for changing a certain lens gap in the projection optical system and a mechanism for adjusting a pressure in an air chamber in the projection optical system.
A position of best imagery plane (focal plane) of the projection optical system and the distortion condition also change due to the same changing factors as those in magnification. There are projection exposure systems provided with a focusing correction mechanism and/or with a distortion correction mechanism as well as with the magnification correction mechanism. For example, the distortion condition of the projection optical system may be adjusted to some extent by slightly inclining the reticle with respect to a plane normal to the optical axis of the projection optical system.
FIG. 12 shows a simplified structure of a conventional projection exposure system provided with a control mechanism of imaging characteristic of the projection optical system. In FIG. 12, reference numeral 101 designates a mercury lamp. Exposure light IL emitted from the mercury lamp 101 is converged by an elliptic mirror 102, and is then reflected by a mirror 103 to enter an input lens 104. The exposure light IL is converted by the input lens 104 into a substantially parallel beam. There is a shutter 106 disposed between the elliptic mirror 102 and the mirror 103. The supply of the exposure light IL to the input lens 104 may be stopped by closing the shutter 106 through a drive motor 107. Numeral 108 denotes a main control system for controlling operations of the entire system, which controls the operation of the drive motor 107. A pulse laser source such as KrF excimer laser or another light source may be employed in place of the mercury lamp 101.
The exposure light IL output from the input lens 104 enters a fly eye lens 105 as an optical integrator, and numerous images are formed as a secondary light source on a focal plane of the fly eye lens 105 on the output side (on the reticle R side). An aperture stop 109 is located at the secondary light source formation plane.
The exposure light IL output from an aperture portion of the aperture stop 109, that is, from the secondary light source, is directed to a beam splitter 110 having a high transmittance but a low reflectance. The exposure light IL 1 reflected by the beam splitter 110 enters a light receiving surface of an integrated exposure amount monitor 111 comprised of a photoelectric converter. A detection signal of the integrated exposure amount monitor 111 is supplied to the main control system 108. The main control system 108 calculates an integrated exposure energy by multiplying the integration value of the detection signal by a certain factor. The exposure light IL having passed through the beam splitter 110 passes through a first relay lens 112, a variable reticle blind 113, a second relay lens 114, and a mirror 115 to enter a main condenser lens 116. The exposure light IL is moderately converged by the main condenser lens 116 to illuminate the reticle R at a substantially uniform illuminance. In this arrangement, the variable reticle blind 113 is located on a plane conjugate with the reticle R and functions as an illumination field stop of the exposure light IL to the reticle R. The main control system 108 controls a drive unit 117 to set a shape of an aperture portion of the variable reticle blind 113 in a certain state.
The exposure light IL having passed through a pattern area on the reticle R is converged on a shot area on a wafer W through the projection optical system PL, whereby a pattern of the reticle R is replicated at a predetermined reduction magnification on the shot area on the wafer W. A Fourier transform plane (pupil plane) of the projection optical system PL is conjugate with the secondary light source formation plane of the fly eye lens 105. Further, the wafer W is held on a Z stage 118, and the Z stage 118 is mounted on an X-Y stage 119. The X-Y stage 119 may two-dimensionally position the wafer W in a plane normal to the optical axis of the projection optical system PL, and the Z stage 118 may position the wafer W in a direction parallel to the optical axis of the projection optical system PL. The main control system 108 controls the operations of the X-Y stage 119 and the Z stage 118 through a control unit 120.
In FIG. 12, numeral 121 denotes an irradiation optical system of a focus detection system, and 122 a light receiving optical system of the focus detection system. The irradiation optical system 121 obliquely projects an image for example of a slit pattern onto an object on the Z stage 118 in an exposure area of the projection optical system PL, and the light receiving optical system 122 receives the image of the slit pattern for example on a vibrating slit plate therein. A photoelectric detector is placed behind the vibrating slit plate. An output signal of the photoelectric detector is subject to synchronous rectification with a drive signal of the vibrating slit plate to obtain a focus detection signal. The thus-obtained focus detection signal is supplied to the main control system 108. The main control system 108 adjusts a height of the Z stage 118 as to keep the focus detection signal at a predetermined level, so that a surface of the object on the Z stage 118 is aligned with the best imagery plane of the projection optical system PL. There is a mechanism for offset adjustment of the focus detection signal, for example, a parallel flat glass an inclination angle of which can be adjusted, provided inside the light receiving optical system 122.
There are an irradiation amount monitor 123 comprised of a photoelectric conversion device, and a reference reflection plate 124 providing a reference for reflectance disposed in the vicinity of the wafer W on the Z stage 118. An irradiation power of the exposure light IL through the projection optical system PL may be measured by moving the X-Y stage 119 to set the irradiation amount monitor 123 in the exposure area of the projection optical system PL. A detection signal of the irradiation amount monitor 123 is supplied through a signal line not shown to the main control system 108.
Numeral 125 represents a characteristic control unit, which adjusts a certain pressure in an air chamber inside the projection optical system PL or which adjusts a certain gap between lenses forming the projection optical system PL. The imaging characteristic such as the projection magnification of the projection optical system PL may be adjusted within a certain range by adjusting the pressure in the air chamber or by adjusting the gap between lenses. The characteristic control unit 125 may further comprise a mechanism for slightly inclining the reticle R to a plane normal to the optical axis of the projection optical system PL. The main control system 108 sets the imaging characteristic such as the projection magnification of the projection optical system PL in a certain state through the characteristic control unit 125, depending upon integrated exposure amount of the exposure light and the reflectance of the wafer W.
The characteristic control unit 125 may control an operation of an offset adjustment mechanism of the focus detection signal in the light receiving optical system 122 of the focus detection system. When it is presumed that the position of the best imagery plane of the projection optical system PL is changed, the main control system 108 adjusts the offset of the focus detection signal of the light receiving optical system 122 through the characteristic control unit 125. By this, the exposure surface on the wafer W is always set on the best imagery plane of the projection optical system PL.
Further, though omitted in FIG. 12, there is a measuring apparatus is provided for measuring a pressure and a temperature around the projection optical system PL. Information about the pressure and the temperature obtained by the measuring apparatus is supplied to the main control system 108.
The exposure light reflected by the wafer W passes through the projection optical system PL, the reticle R, the main condenser lens 116, the mirror 115, the second relay lens 114, the variable reticle blind 113, and the first relay lens 112 to return to the beam splitter 110. The exposure light IL 2 reflected by the beam splitter 110 enters the light receiving surface of the reflectance monitor 126 composed of the photoelectric conversion device. A detection signal detected by the reflectance monitor 126 is supplied to the main control system 108. The main control system 108 moves the X-Y stage 119 through the drive unit 120 to sequentially set the wafer W and the reference reflection plate 124 in the exposure area of the projection optical system PL, whereby detection signals of the reflectance monitor are obtained corresponding to the wafer W and the reference reflection plate 124. The reflectance of the wafer W may be obtained for example from a proportional relation by preliminarily storing the reflectance of the reference reflection plate 124. An example of the method for measuring the reflectance of the wafer W by means of the reflectance monitor 126 is disclosed in U.S. Pat. No. 4,780,747.
In the projection exposure system of FIG. 12, an ordinary secondary light source, light of which is distributed on a circle in a region including the optical axis of the illumination optical system, is used as the secondary light source of the exposure light. The .sigma. value representing a degree of coherency of the exposure light IL, which is a ratio of a radius of an image of the secondary light source on the pupil plane of the projection optical system to a radius of the aperture stop of the projection optical system PL, is fixed for example at about 0.5, because the line width of pattern on the reticle R to be replicated ha been comparatively wide heretofore. In this arrangement, a beam of the exposure light IL is comparatively fine immediately after the secondary light source defined by the aperture stop 109, and, therefore, the beam splitter 110 employed may be of a relatively small size, whereby a less load is forced on the structure of the illumination optical system.
Problems in the second prior art
However, as the pattern of the reticle R to be replicated becomes finer and finer these days, some exposure systems employ an illumination optical system having a larger .sigma. value than 0.5. There has also been developed a projection exposure system which can use a phase shift reticle and a normal reticle as the reticle R while switching therebetween. An illumination optical system in such an exposure system requires a mechanism for changing the .sigma. value in a comparatively wide range. Applicants have proposed the so-called plural oblique illumination method in which the resolution of the projection optical system can be increased while maintaining the depth of focus comparatively deep. In the plural oblique illumination, the secondary light source of the exposure light is formed for example by four modified secondary light sources eccentric to the optical axis of the illumination optical system and separate from each other, and the reticle is obliquely illuminated by the four secondary light sources for example in four directions.
In the plural oblique illumination method, since the four secondary light sources of the exposure light are distributed in a region apart from the optical axis of the illumination optical system, a circle circumscribing the entire secondary light sources has a large radius, whereby the substantial c value of the illumination optical system becomes approximately 1. With the .sigma. value of about 1, an outer diameter of the secondary light sources, corresponding to the opening of the aperture stop 109 in FIG. 12, increases, whereby increasing a diameter of beams of the exposure light output from the secondary light sources.
Further, as the pattern to be replicated becomes finer and finer, the requirements accuracy of illuminance uniformity of the exposure light illuminating the reticle R is required to be higher and higher and the requirements accuracy of illumination telecentricity, which is a degree of parallel of the exposure light, is also required to be higher. Under such circumstances, if a beam splitter for splitting the exposure light is placed between the optical integrator such as the fly eye lens and the lens system such as the relay lens, accuracies for other elements in the illumination optical system must be set extremely high enough to obtain a required imaging characteristic, or the number of necessary lenses is increased, whereby a hard load is forced on the designing and the production of the illumination optical system.


A freezing cycle apparatus having quick freezing and thawing functions which is capable of implementing a quick freezing function of foods using an auxiliary evaporator installed in a freezing cycle apparatus, dividing a freezing chamber of the refrigerator into a quick freezing chamber and a common refreezing chamber, and using the thusly divided quick freezing chamber. The apparatus includes a compressor, a three-way valve connected with one end of the compressor, a main evaporator connected with one end of the three-way valve, a phase separator connected with one end of the main evaporator, a first capillary tube connected with one end of the phase separator, a first check valve connected with one end of the first capillary tube, a common freezing unit one end of which is connected with the first check value and the other end of which is connected with the other end of the compressor, which is comprised of a main evaporator, and a quick freezing and thawing function unit connected with the common freezing unit and including an auxiliary heat exchanger, a plurality of capillary tubes, an opening/closing valve, and a check valve.

1. Field of the Invention
The present invention relates to a freezing cycle apparatus having quick freezing and thawing functions, and in particular to an improved freezing cycle apparatus having quick freezing and thawing functions by which it is possible to selectively use a function between a quick freezing function and a quick thawing function for a refrigerator.
2. Description of the Conventional Art
As shown in FIG. 1, a conventional freezing cycle apparatus includes a compressor 1 for changing a gaseous refrigerant of a low temperature and pressure to a high temperature and pressure gaseous refrigerant, an condenser 2 for changing the thusly changed high temperature and pressure gaseous refrigerant to a high temperature and pressure liquid state refrigerant which acts and radiating heat to the outside of the refrigerator, a capillary tube 3 for changing the liquid state refrigerant into a low temperature and pressure liquid refrigerant, an evaporator 4 for changing the liquid state refrigerant which is changed to a low temperature and pressure by the capillary tube 3 to a gaseous state refrigerant, thus absorbing external heat, and a refrigerant tube 5 connecting the condenser 1, the compressor 2, the capillary tube 3, and the evaporator 4, respectively.
The above-described refrigerating cycle is generally adapted to a refrigerator or an air conditioner and is directed to storing foods in a fresh state and conditioning an indoor environment by cooling or heating the indoor air by installing the evaporator 4 which absorbs an external heat and the compressor, which 2 externally radiates the thusly absorbed heat.
The refrigerating cycle may have a quick freezing or quick thawing function. The quick freezing and quick thawing function will be explained in more detail with reference to FIG. 2. In a refrigerator having a fan 11 and an evaporator 12 which are installed behind a grill fan (not shown) in a freezing chamber 10, in the quick freezing mode of the conventional refrigerator, as shown in FIG. 3, the air cooled by the evaporator 12 is introduced into the freezing chamber 10 forcibly by the fan 11. The thusly introduced cooled air flows toward the evaporator 12 through the paths formed in the refrigerating chamber 10.
Namely, a damper 14 for the freezing chamber 15 is operated by a selection switch (not shown) or a selection button (not shown). When the damper 14 is closed, the cooled air flowing into the refrigerating chamber 15 is blocked, and only the freezing chamber 10 is operated.
However, in the freezing cycle of the conventional quick freezing refrigerator which is operated identically to a state that the refrigerator is normally operated, since a damper is installed in the refrigerator for controlling the amount of refrigerant, thus operating only the freezing chamber. Therefore, 3 (three) hours are required for the quick freezing operation, assuming that a standard test package having a thickness of 5 cm and a weight of 500 g is used for attempting to decrease a temperature from -5.degree. C to -1.degree. C. within 30 minutes. Therefore, it is impossible to actually enable a quick freezing operation within 30 minutes which is required for fully preventing the expansion of a water molecular structure contained in the food to be frozen.
In addition, the conventional apparatus which is configured to include a quick freezing and quick thawing cycle will now be explained.
First, the cycle of the conventional freezing cycle apparatus having a quick thawing function will now be explained with reference to FIG. 4 which is performed as follows: the compressor 1 the condenser 2 a first capillary tube 3 an opening/closing valve 8 a main evaporator 4 a check valve 9 a compressor 1, so that the common freezing function is performed. Here, a first cycle is defined as one circulation during which the common refrigerating function is performed once.
At this time, a second capillary tube 7 is connected between the first capillary tube 3 and the opening/closing valve 8, and an auxiliary evaporator 6 is connected with one end of the second capillary tube 7.
The other end of the auxiliary evaporator 6 is connected between the compressor 1 and the check valve 9.
The quick freezing cycle of the freezing cycle apparatus having a quick freezing function is performed as follows: the compressor 1 the condenser 2 the first capillary tube 3 the second capillary tube 7 the auxiliary evaporator 6 the compressor 1, thus performing the quick freezing function.
At this time, the refrigerant which became a low temperature and pressure by the first capillary tube 3 passes through the second capillary tube 7, and the pressure thereof is decreased thereby, and then the refrigerant passes through the auxiliary evaporator 6, so that the quick freezing function (here, the cycle of performing the quick freezing function is called as a second cycle) is performed.
However, when performing a quick freezing operation using the freezing cycle apparatus having a conventional quick freezing function, since the refrigerant does not flow to the main evaporator, when the apparatus is operated for more than a predetermined time, the temperature of the interiors of the freezing chamber and refrigerating chamber in which the main evaporator is installed is increased.
In addition, the cycle of the freezing cycle apparatus having a conventional quick thawing function is performed as follows: the compressor 1 a three-way valve 8 the condenser 2 the check valve 9 the first capillary tube 3 the evaporator 4 the compressor 1, for thus performing a common freezing function.
During the freezing cycle, the gaseous refrigerant is changed to a liquid state refrigerant by the condenser 2, thus radiating heat to the output side of the refrigerator.
At this time, in order to perform the quick thawing function, an auxiliary condenser 6 is connected with the three-way valve 8 for performing a quick thawing function. The second capillary tube 7 is connected with an end portion of the auxiliary condenser 6, and the other end of the second capillary tube 7 is connected between the check valve 9 and the first capillary tube 3.
The quick thawing cycle of the freezing cycle apparatus having a conventional quick thawing function is performed as follows: the compressor 1 the three-way valve 8 the auxiliary condenser 6 the second capillary tube 7 the first capillary tube 3 the main evaporator 4 the compressor 1, for thus performing a quick thawing function (here, the above-described cycle is called as a third cycle in which the quick thawing cycle is performed).
However, as described above, in order to concurrently perform the quick freezing and quick thawing operations, an additional cycle should be disadvantageously performed.

Freezing cycle apparatus having quick freezing and thawing functions


A system and method for shopping, using a personal computer operated from a convenient location such as home, for fitted eyeglasses that can include either prescription or non-prescription lenses. A customer visits one of possibly several different customer diagnostic locations where digital images of the customer's head and face are acquired using various known techniques so as to obtain size and image data with respect to the customer. The customer then receives a password and information on how to connect to a computer (remote electronic store) associated with the various customer diagnostic locations. When the customer later connects a personal computer to the remote electronic store using the password issued by the customer diagnostic location, the remote electronic store provides images to the personal computer of how the customer would appear wearing different eyeglasses having frames fitted precisely to the customer's head based on the size and image data acquired at the customer diagnostic location. Alternatively the remote electronic store will download to the customer's personal computer an application that will construct the displays of how the customer would appear wearing different eyeglasses. The remote electronic store can further use frame selection data input by the customer related to the customer's lifestyle preferences. This information in combination with the size and image data is used by the remote electronic store to select a subset of frames best suited to the customer. The customer can purchase selected eyeglasses for direct delivery or for pick-up at a selected optical retail location.

1. Technical Field
The present invention pertains to the field of eyeglasses. More specifically, the present invention is concerned with fitting frames for eyeglasses to a customer and displaying to the customer, on a personal computer operated from a convenient location, such as the customer's home, how the customer would appear wearing the fitted eyeglass frames. The invention is further directed to obtaining information from the customer so as to help select a subset of eyeglass frames from the total set of frames available, and for displaying fitted images of eyeglass frames from the subset of frames to the customer.
2. Description of Related Art
As microcomputers have become increasingly powerful, more and more effort has been invested to enable offering products to a customer using a microcomputer to display the products. For selling products that a customer would wear, these efforts have resulted in systems in which a microcomputer adjusts the size of a product and, using a predetermined image of the customer, shows the customer how the customer would appear wearing the product. In particular, U.S. Pat. No. 5,280,570 to Jordan is directed to a system that shows a customer how the customer's eyes would appear to another person because of wearing eyeglasses with a certain prescription, causing the customer's eyes to appear larger or smaller, depending on the prescription, than without the lenses. This particular system includes elements that allow a customer to try on various eyeglasses, observe how the customer would appear wearing the eyeglasses, and place an order. The system uses lifestyle information obtained from the customer to limit what models of eyeglass frames it suggests to the customer. All of the elements of this system are physically collocated in a store where the customer must go in person to electronically try on the glasses and to place an order.
U.S. Pat. No. 5,515,268 to Youda discloses a system where a customer selects a product at a storefront location from a product list stored in a computer at a remote location. In this system a sensor detects customer size information and transmits it to the remote computer. The remote computer then selects a product of appropriate size and sends an image to the storefront for display on a monitor, showing the product superimposed on the customer. The product is fitted to the customer's body image using various computer transformations. Although the invention is not directed to a particular product, it teaches the use of an actuator in the form of a loop, which transfers product information to the customer. Such an actuator is of no use in fitting eyeglasses to a customer.
In U.S. Pat. No. 5,592,248 issued to Norton et al, a method is provided for fitting eyeglasses to a customer by taking pictures of the customer at one location and transmitting those pictures to a remote location where the pictures are examined in a way that allows an accurate determination of the shape and size of the customer's head so that eyeglass frames may later be custom manufactured. Norton, however, does not teach or suggest showing the customer how the customer would appear to others while wearing different pairs of eyeglass frames.
In all of this prior art, the customer places an order at a storefront after trying on glasses at the storefront. In the case of Youda, although the order is transmitted to a remote computer, the product is nevertheless ordered at a storefront and tried on at a storefront.
What is needed is a way of enabling a customer to try on eyeglass frames at home and order from home a pair of eyeglasses after having an opportunity to carefully consider many different eyeglass frames, in order to more likely meet the customer's needs. Trying on the eyeglasses at home (electronically) allows the customer to make a decision without any sense of urgency. For an investment in a product that can last at least several years, and that is crucial to the customer's daily comfort, providing a method that encourages the customer to take the time needed to arrive at a prudent decision benefits the customer and also the merchant, to the extent the customer is satisfied with the purchase. In addition, such a system could make custom fitting frames economically feasible where in some cases it is not; in such a system, the cost of supplying eyeglasses could be allocated more to manufacturing custom-fitted frames because of saving the cost of paying an attendant to wait on a customer. Furthermore, by making the selection process easier to the customer, the customer may be more likely to purchase new eyeglasses as compared to traditional selection techniques.
What is further needed is a method of assisting a customer in the selection process of eyeglass frames. The present invention, by its ability to electronically store information concerning eyeglass frames, is not limited with respect to the inventory of frames that can be maintained by the system; unlike a retail optician that must necessarily limit the potential choice in eyeglass frames.
What is still further needed is a method that can further assist the customer in eyeglass frame selection by questioning the customer, such as via a questionnaire, so as to obtain relevant information concerning the customer's lifestyle and customer's preference in eyewear. Such information can then be processed in conjunction with the customer's physical head and face measurements to select a subset of frames from the total set of frames maintained in the system's frame database.
What is also needed is such a system that provides a convenient method of ordering the desired eyeglass frame, including having delivery at home or order fulfillment at any one of a number of optical retail locations.

System and method enabling shopping from home for fitted eyeglass frames