JPH07509350A - Imaging system with optimized electrode array for processing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Imaging system technology field that performs processing with optimized electrode arrays TECHNICAL FIELD This invention relates to systems for producing images, and more particularly to photoconductive systems that absorb radiation. The member is used to form a latent image, and the latent image is subsequently formed within the photoconductive member. The present invention relates to a system for selectively detecting images.

Background technology Some imaging systems use light that absorbs the incident radiation to represent an image of the object. Some use conductive members. A suitable photoconductive member absorbs this radiation and generates an electrical current. This will give rise to child-hole pairs (charge carriers). Electron-hole pairs are photoconductors separated from each other by an electric field applied across the faces of the photoconductor (generally , which is a thin planar layer) will form a latent image. A narrow beam of scanning radiation By causing the movement of a second set of charge carriers, the discharge of the photoconductor is effectively Achieve goals. The distribution of such second charge carriers in the plane of the photoconductor is , a is influenced by the initial charge carrier distribution, ie the latent image. second charge The movement of the carrier is detected and digitized with suitable circuitry, and in this way the latent image is Captured in digital format.

In one particular embodiment, the photoconductor comprises two photoconductors with a photoconductive layer and an insulating layer between them. It is part of a multilayer structure with several electrodes. High voltage power supply allows for incident radiation and scanning Maintaining an electric field within the structure during exposure to radiation (although during each exposure (The same electric field strength does not necessarily exist in both cases.) This type of system An example is taught in U.S. Pat. No. 4,176,275 (Kohn et al.). ing. Application of an electric field across the photoconductive layer is described in U.S. Pat. No. 4,539,591. Before (opposite) crossing the insulating layer, as taught in the specification (Mr. It is possible to be helped by establishing an electric field.

A second closely related approach is the air-gap photoinduced discharge (PID) method. This method uses air as an insulating layer and is generally used for high-precision machinery. Equal separation is maintained between the two electrodes by a piezoelectric device or a piezoelectric device. It is necessary to Before exposure to radiation, the corona charges the photoconductor surface and Creates an electric field within the material. Therefore, the incident radiation partially discharges that surface and , giving rise to a latent image, and the readout signal absorbs the influence of the remaining electric field in response to the scanning radiation. induced by the charge transfer it undergoes. Such a system was developed by Roland et al. , Med, Phys, Volume 18, No. 3, May 1991/Reg. No. 412 It is disclosed on pages 431 to 431.

There are various methods of scanning a latent image. For example, U.S. Patent No. 4,961.20 No. 9 (by Mr. Rowland) discloses a transparent sensor positioned on a photoconductive layer. electrode and a laser pulse that scans the photoconductive layer through this transparent sensor electrode. Ru.

The photoconductive layer and the transparent electrode are moved relative to each other, and the direction of the relative movement is scanned by a laser. By making the direction transverse, the per-vixel discharge of charge carriers is triggered.

Practical applications of such systems have encountered some problems.

First, the fabrication of the imaging stack (i.e., electrodes, insulators, conductive members, etc.) The process generally consists of composing two substacks and then attaching them to each other. Therefore, it is necessary to adhere the component layers to each other. These steps are This can lead to non-uniform thickness of the stack.

Second, reflection and scattering of the incident radiation can occur at the interface between the layers. , reducing image quality. This problem and attempted solutions to this problem The problem is further exacerbated by the non-uniformity of the thickness.

Thirdly, discharge dielectric breakdown of insulating members occurs, especially in the air gap PID method. may cause avalanche currents in the system.

Fourth, given the needs of practical applications such as chest X-ray, the imaging stack As the areal dimension of increases, the capacitance formed by the electrode plate increases. greatly reduces the efficiency of the system. One approach to this last problem is the approach of U.S. Pat. No. 4,857.723 (Modesette). Ru.

This approach uses many small detectors grouped together This avoids rather than solves this capacitance problem. There is.

The present invention relates to an image formed by radiation incident on an imaging device. It is a system that causes The imaging device includes a first conductive layer and an insulating section. a photoconductive insulating layer, an electrically blocking layer, and a second conductive layer (dividing the conductive electrode). ), in this order. The system further comprises: an electric field forming means for forming an electric field between the first conductive layer and the second conductive layer, the electric field forming means forming an electric field between the second conductive layer and the second conductive layer, formed by the absorption of rays and separated to form a current, resulting in A latent image due to static electricity is formed at the interface between the insulating member and the photoconductive insulating layer. The electric field forming means is provided. The present invention includes a scanner. Scanner first time Activate a single spot on the above imaging device once, each in an ordered pattern. The spot carries movable charge carriers within the imaging device. A second current is generated that includes the second current. Finally, the system is connected to a conductive electrode and above further comprising detection electronics sensitive to the movement of the charge carriers, Sensitivity is matched for the members of the array in a second time-ordered pattern. Main departure To complete the invention, the electrode array is a plurality of elongated strips, each strip the scanner is positioned in a second direction substantially different from the first direction; 1 member of the image, the electronic circuit scans the array, and the electronic circuit scans 1 member of the image. As a first step, a match between the first and second patterns is analyzed. Therefore, the image A pixel representation of the image is generated. This system provides improved output signal strength and It has higher resolution than known systems.

Brief description of the drawing FIG. 1 is a schematic diagram of one embodiment of the invention.

FIG. 2 is a schematic illustration of another embodiment of the invention.

FIG. 3 is a schematic electrical circuit diagram of a preferred amplifier for use with the present invention.

FIG. 4 is a cross-sectional view of a portion of the embodiment of FIG.

FIG. 5 is an electronic signal trace for an amplifier circuit according to the invention.

FIG. 6 is a graph of characteristics of an embodiment of the present invention.

FIG. 7 is a schematic representation of an electrode strip according to the invention.

8 and 9 show the signal strength as a function of the number of vixels for the detector according to the invention. It is a graph showing degree.

Figure 10 shows the signal strength as a function of electrode strip width for a detector according to the invention. This is a graph diagram.

Detailed description of the invention The basic configuration of the present invention is illustrated in FIG. One imaging device 10 It comprises a stack of laminated layers. That is, the first conductive insulating layer 12 and , an insulating material 14, a photoconductive insulating layer 16, an electrically blocking layer 18, and a second electrically conductive material. layers 20 in this order (from top to bottom as shown). Second conductive layer 20 uses a segmented array of conductive electrodes in the illustrated 16-channel embodiment. 20a to 20p (the number of channels of Ili! is also possible).

Although not shown for clarity, in the actual configuration the laminated strips The tack support is, for example, a transparent support substrate and/or some type of mechanism. Calframe will commonly be used. The laminated stack consists of individual structures. The components may be assembled onto a substrate and then placed into a frame. but , by appropriate selection of materials, the laminated stack can be applied to substrates or mechanical frames. (Thus, the present invention does not require a board or mechanical frame.) It is not limited to those requiring the use of systems.

Provided that the electrical properties and transparency described below are taken into consideration, the material of Suitable for each layer of the stack. Generally, if a substrate is used, the substrate It may be any material that provides mechanical support, dimensional stability, and low electrical conductivity. For example, about Glass with a thickness of 2 to 4Lll11 is a suitable substrate, on which a flat conductor can be placed. A second conductive layer is formed by depositing a conductive film and then etching away unnecessary material. A partitioned array may be formed.

The preferred material for the photoconductive insulating layer is amorphous selenium, which can be deposited by conventional methods. May be included in a layered stack. Among the pond materials, lead oxide, cadmium sulfate and mercurous iodide are suitable as they are organic photoconductors. General In the absence of radiation, the photoconductive insulating layer has a current of, for example, about 109 ohms - As for values larger than that, the conductivity is low and the electric field becomes photoconductive for a sufficient period of time. will be maintained across layers.

The thickness of the photoconductive insulating layer is such that it can absorb about 50% or more of the incident radiation flux. (discussed below). For example, amorphous selenium and For X-ray radiation detection, this thickness is approximately 250-550 micrometers. .

Insulating materials are fluid materials (including gaseous materials such as air) at the operating temperature of the system. ) or a layer of non-fluid material at the operating temperature of the system. good.

The insulating layer is typically 100 to 300 microns thick. The insulation layer is For example, evaporation of poly-p-xylene or union carbide "Parylene-C" It may be formed by the use of deposited polymeric materials. This material can form a layer of uniform thickness. preferred due to its ability to However, if the material is deposited from a point source, this ability is adversely affected. Alternatively, for example, a gold layer deposited on a polymeric film and light added to the stack by the use of optical adhesives. As in that product, the first conductive layer is separately deposited on a flexible insulating material. It's okay to be.

A voltage source 22 creates an electric field between the first and second conductive layers 12 and 20 to Electron-hole pairs (see below) formed in the electrical layer are caused by the first incident radiation 30. and are separated within the imaging device 10. 5~20v/ Micron electric fields are common. The electric field strength at the higher end of this range is Improve the carrier separation efficiency of the stem. Generally, but not necessarily , when amorphous selenium is used, the electrical blocking layer is is also chosen such that the positive pole is near the electrode. And the same relative diameter is the system used in all stages of operation. However, if properly adjusted, this is also necessary. There isn't. For example, when the photoconductive insulating layer is exposed to uniform radiation, the first electrode With respect to the second electrode, it may be negatively biased, whereby the photoconductive layer and the insulating layer A uniform charge density is formed at the interface with the Therefore, the current across the insulator The field is much higher across the photoconductive layer. During the exposure of the incident radiation, the voltage source is adjusted For example, by using a voltage source value of 0, the voltage across the insulating layer can be reduced. The pressure is shared with the photoconductor.

The incident radiation causes an irradiation by forming charge carriers within the photoconductive insulating layer 16. Leaves a latent image in the imaging stack. The charge carriers are formed by voltage source 22. separated due to the influence of the electric field generated. This means that the imaging device 10 has a 1 current and induces an electric field in an image pattern, resulting in the insulation material 14 and An electrostatic latent image is formed at the interface 24 with the photoconductive insulating layer 16. this To prevent the latent image from dispersing, an electric field of about 1-5 V/micron is applied to the voltage source 22. and relatively slow dark decay of the photoconductive layer to maintain the electric field. y) by relying on the speed or other voltage source (not shown) at its field strength. ) may be left across the structure by keeping it constant.

The image of interest enters the imaging stack from either side The shape of the pattern of incident radiation 30. In FIG. 1, the incident radiation 3o is Although it is incident from the direction of the array, this is just an example. In this example , the arrangement of electrodes and the electrically blocking layer 18 at the wavelength of the incident radiation 3o. , must be semi-transparent. In a preferred embodiment of the invention, X-rays (10-' is designed for use with incident radiation in the form of . A thin metal layer (e.g. aluminum) is sufficiently translucent to this X-ray. Ru.

During the readout phase of the operation, typically 1 to 5 μm across the laminated stack. /micron third field strength is maintained and most preferably used during image exposure. The polarity is opposite to that used. The scanner 26 has a first time order (first time order). imaging using scanning radiation 28 in a time-ordered) pattern. The imaging device 10 is activated to generate mobile charge carriers within the imaging device 10. A second current is generated.

The scanning radiation 28 may be of substantially the same wavelength as the wavelength of the incident radiation, or may be of substantially the same wavelength as the wavelength of the incident radiation. The wavelengths may be qualitatively different. Scanning radiation 28 can be ultraviolet, visible, or red. Good as an outside line.

Generally, the first time-ordered pattern is the surface of the laminated stack that retains the latent image. This will ensure that the entire area is scanned. That is, the preferred pattern is Scan the entire surface of the stack. Because until the scan is completed, This is because the location of the image is not known. The highest resolution and most efficient operation To achieve this, any point on the surface is scanned only once, and no point is left unscanned.

The preferred pattern is a series of parallel lines, each running in the same direction. Allow time for the scan to progress and for the scanner to return to the other side of the stack between lines. .

Such patterns may be placed at an angle of up to 45 degrees to the direction of the electrodes. is possible, but is preferably arranged at right angles to the orientation of the electrodes.

Scanning radiation 28 is absorbed by photoconductive insulating layer 16 . In general, scanners are The scanning radiation is within the visible wavelength range. The wavelength is within the photoconductive layer. determined by the energy required to excite charge carriers at . For amorphous selenium photoconductive insulating layers, blue-green lasers are suitable.

Although the laser has favorable focusing and intensity characteristics, its coherence (interference) is unfavorable. Tips on insulating layers with non-zero thickness The use of a lens light source creates interference effects. This effect is caused by By reducing the reflection of scanning radiation, e.g. The diameter can be made smaller by using an anti-radiation coating. this A method for achieving this is described in U.S. Pat. No. 4,711,838 (Mr. It has been taught in many sources, including

In the embodiment shown in FIG. 1, the scanning radiation 28 is applied to the first conductive layer 1 prior to absorption. 2 and the insulating layer 14. do. This is just an example. This is because, as shown in Figure 2, before absorption Also, by passing through the second conductive layer 20 and the electrically blocking layer 18, This is because the scanning radiation 28 can activate the imaging stack 1o. which Even in cases where the conductive layer through which the scanning radiation passes is at the wavelength of the scanning radiation ( For example, at wavelengths on the order of a few hundred nanometers typical of visible lasers) Must be transparent. Generally, both conductive layers are made of a thin metallic ( metalHc) structure (e.g. gold) or relatively thick non-metallic non-oetallic structures (e.g. 0.1 to 0.5 micron thick) (indium tin oxide), so it would be translucent. electrical blocking layer 18 must also be translucent, typically 0.01 to 0.1 microns thick. be. Since the insulating layer 14 has a polymer structure (for example, polyester), it is transparent. Will. Also, if there is a substrate and radiation passes through the substrate, the substrate is Must be transparent at the wavelengths involved.

As shown in FIG. 2, the array of electrodes 20 is a plurality of elongated parallel strips. X-ray radiation In ray applications, strip widths of 10 to 200 microns are preferred. Array is single When acting like a continuous conductive plate of (not shown in FIG. 2).

The orientation of the electrodes 20 is substantially different from the direction of the scan performed by the scanner 26. Must be different. That is, the scanner 26 The array is scanned in the "horizontal" direction and the electrodes are located in the "horizontal" direction as indicated by arrow 34. There is. Thus, as shown, directions 32 and 34 are perpendicular to each other.

However, other substantially different modifications to the detection electronics 40 may be considered. direction is possible.

The latent image is captured by detection electronics 40 attached to the conductive electrode 20; is influenced by the motion of the charge carriers caused to move by the scanning radiation 28. water. For each electrode, the induced charge change is detected and amplified to produces a signal representing the acquisition of a portion of .

The sensitivity of the detection electrodes 40 is adjusted to the number of arrays 20 in the second time order pattern. be given A single electrode is made more sensitive than adjacent electrodes. This is the adjacent electrodes at “effective” or “vertical” ground level with respect to a single electrode between them. voltage to this single electrode (not necessarily at absolute ground level). By triggering the integrator circuit to start collecting the load, It is done. For example, given the parallel lines of the first time order pattern described above, , a second time-ordered pattern will follow in the "direction" of sensitivity. That is, The position of the most sensitive electrode as a function of time is determined by the It will appear to move across the layered stack repeatedly in the same direction. cormorant. This apparent motion is the result of each stack allowing the scanner to move to the next line. It will be synchronized to a scanning pattern that includes pauses at the edges.

Thus, by appropriate adjustment of the first and second time order patterns, the detected electron The circuit 40 calculates each pixel as a pixel of the image produced by the incident radiation 30. Analyze the match between the first and second patterns. This is U.S. Patent No. 4,176.27 No. 5 (Kohn et al.), a single line shaped putter. In this type of system, a single elongated electrode is scanned and an electronic circuit is This contradicts the known practice of adjusting the electrodes and reading all electrodes simultaneously in a parallel manner.

FIG. 2 shows how an array of elongated electrodes is attached to detection electronics 40. An example of how it is possible is shown below. However, other techniques are also possible. illustration For convenience, only nine electrodes are shown in FIG. In other words, the inclusive number one The electrodes from the eye to the 1st, the Nth electrode, and the inclusive N+1st to N+4th electrodes The electrodes up to th are shown. Starting from the 1st electrode, every Nth electrode The microstripes are electrically connected to each other. In other words, the 1st and N+1st The electrodes are connected, similarly, the second and N+2 electrodes, and the third and N+3 electrodes. Connected like electrodes. Thus, an N channel is formed from M electrodes. It's fine. Here, M must be greater than N, but only N circuits are required. too Naturally, up to M circuits can be used.

Although not shown in FIG. 2 for clarity, the electrode arrangement preferably includes: Includes start-scan and end-scan electrodes at each end of the array, with each electrode If so, it may have a dedicated circuit. This allows electronic circuits to be aligned with the scanning radiation. can be clearly identified in which of these positions the The detection circuit can be synchronized to the detected line.

FIG. 3 shows an electrical schematic of a preferred circuit 50 for each channel of N-channels. ing. The circuit 50 includes three combinations of circuit elements 51, 53, and 55. Ru. The first combination 51 includes an operational amplifier 52 and a compensation capacitor 56. and a feedback resistor 54 connected in parallel. Operational amplifier 52 is Burl Brown○P A637. Feedback resistor 54 may be 1x107 ohms. can. Compensation capacitor 56 may be 70 femtofarads.

This combination of circuit elements is responsible for converting charge pulses into corresponding voltage pulses. It works as a transimpedance amplifier.

A second combination of circuit elements 53 acts as a low pass filter and is connected to a resistor 64. and a capacitor 66. This low-pass filter has a low response at the desired frequency. should be designed to This combination of elements is included in circuit 50. There's no need to be discouraged.

The third combination of circuit elements 55 is an au pair such as Burl Brown 0PA627. 72 and a capacitor 76, such as a 0 to 20 microfarad. Variable human resistor 74 with kiloohm resistance and Silicoex VNO300M a remote control switch 78, such as an N-channel enhancement FET. . This combination of circuit elements acts as a switched integrator controlled by an external signal. It works. Resistor 74 is configured to provide the desired integral response in voltage per coulomb. is adjusted to The voltage output of the integrator is controlled by an external signal. It can be extracted by a chyplexer.

Conventional timing circuits convert N-channel input signals into M-line vertical resolution. used by detection electronics 40 (shown in FIG. 2) to process good. In the horizontal direction, a scanning radiation 2 easily controlled by a scanner 26 The resolution is determined by the displacement of the 8 paths. In a preferred embodiment, N= 32 and the spacing between electrode centerlines is 170 microns (approximately 5 microns per millimeter). ゜9 electrodes). And the lateral displacement of the scanning radiation is the square millimeter of the image Approximately 5.9 lines are used to produce approximately 34.6 preferred square pixels per should be relevant/related.

Preferably, each electrode has a width equal to 10-90% of the spacing between electrode centerlines; More preferably, it has a width of 50 to 80%. Values outside this range are This will increase capacitance. Also, in a range smaller than this range, It tends to increase electrode resistance and make manufacturing difficult.

Surprisingly, even if the electrodes do not cover the entire surface area of the stack, each There is no essential loss of available charge collected by the electrodes. This is applied The lateral movement of charge carriers formed in the region between the electrodes under the influence of the electric field Therefore, despite the use of segmented electrodes, the entire image can be restored. It is.

FIG. 4 shows a cross-section of a portion of the system shown in FIG. Electrodes 20q and 20 r indicates a member of the electrode array forming the second conductive layer 20. Electrodes 20q and 20 There is a gap between r and therefore a portion of the image 30 is It looks like you can't catch it. However, the edge of electrode 20q shown as point 21 When the charge carriers collected at the point 25 are generated around the point 25, they take a path from the interface 24. It may have moved along 23. Similarly, electrode 20r shown as point 27 The charge carriers collected at the edge of move along path 29 from around point 25. I might have done it. In this way, charge carriers are collected from the entire area of interface 24. All charge carriers formed at interface 24 are transferred to electrodes 20q and 20r. Therefore, it can be collected. Similar results occur for all electrode pairs in the array.

Of course, the applied electric field strength, the thickness of the photoconductive insulating layer, and the spacing between the electrodes are Trajectories and velocities of all charge carriers (toward and in the direction of the first conductive layer) ) is optimized for complete recovery of charge carriers at the interface. It will be done.

Although not preferred, it is also possible for a single electrode to support multiple resolution lines. , and therefore more than one pixel of the electrostatic image in the vertical direction (but would be produced by a single strip of columns. This is a dimension smaller than the width of the strip. using multiple scans of an intensity-modulated laser spot with This can be achieved by scanning at high speed. Each scan consists of a strip of It will include modulation of the brightness of smaller spots on different sub-parts.

Also, the first and second time-ordered steps are performed periodically between each scanned line. It may be synchronized again (eg, at least once per scan).

Scanned images may be processed in many ways. Generally, after scanning, electronic The circuit processes image signals through analog/digital circuits. image of Each pixel is a number (preferably at least 12 bits) representing the brightness of the image. It is expressed as A single line of an image is taken as a single block of data. It is okay to be treated as such. Coherence with non-zero thickness insulation layers, unless already done so. The interference effects for the lentic light source are preferably eliminated by digital image enhancement techniques. should be removed from the image. Preferably, “win towing” ( The "ind1g)" technology processes 8 bits from a 12-bit value and displays it on a monitor or hardware. Increase the contrast of an image before displaying it on a copying device.

Using a single scanned point beam of light and placing it adjacent to a photoconductive insulating layer Collection of induced current using segmented narrow electrodes is known in the art. It offers several independent advantages over other systems.

First, compared to when the signal is collected at a single electrode placed adjacent to the insulating layer, However, the present invention provides greatly improved resolution. The advantage of this is that the split itself rather than the result from a segmented electrode arrangement. For example, a 350 micron thick selenium layer, 175 micron thick polycarbonate insulation layer, and 100 mm center-to-center For micron strip electrodes, when the strip is adjacent to the photoconductor, 5 A latent image pattern of 5 cycles/second can be resolved at 0% contrast. If the strips When adjacent to the insulation, the strips form a pattern of less than 1 cycle/rare. It is possible to show 50% contrast only when the image is on.

Second, the segmentation of the electrodes allows different parts of the imaging stack to be separated by the use of multiple amplifiers. The whole image can be detected in a smaller amount by taking turns. It takes a long time to form. With duplex amplifiers, a single amplifier While the radiation continues on other areas of the image, all that appears on the corresponding electrode can wait for all charges to reach a single electrode. Cohn et al. However, they used a linear (rather than a point) radiation source; Each strip of the divided array has a dedicated circuit and all such amplifiers must operate at the same time. The use of point-scanning radiation sources is subject to several details. Allows the pieces to be connected together into a single amplifier, allowing all amplifiers to be connected together at exactly the same time It is not necessary to operate on

Third, compared to the signal obtained from a given pixel placed on a wider electrode, Thus, a narrow strip electrode has a 10% to 80% increase in the measured signal magnitude. Gives an increase up to. This means that the faster the image acquisition speed, the more signal detection This is in stark contrast to the prior art idea that there is a loss in output efficiency.

Fourth, each amplifier has a capacitance of M2 It is loaded by the capacitance of only S strips. The amplified noise is Since the capacitance increases with size, the electrode division corresponds to each amplifier. Reduce the magnitude of electronic noise.

Each such independent advantage may result from the present invention. However, these All of these in combination with each other provide significant advantages of the present invention over the prior art. The extractor was constructed as described and illustrated above. The first electrode is on the glass substrate multiple groups of unconnected parallel strips with a centerline spacing of 170 microns. Made by vapor depositing pieces. Additional deposition near the edge of the strip is every 32nd strip was connected to one bus electrode terminating at the connector pad end. This is it Thus, each strip could be connected to one of a set of 32 amplifier circuits. scan open Start of scan (5O3) and end of scan (E.O.3) strips were added and connected to the pads. And about 400 micro This strip is followed by a thin layer of amorphous selenium, and an oxide pro-soak is applied on top of this strip. A layer was formed. and one layer of polycarbonate 175 microns thick. of insulation was attached to the selenium layer using photoadhesion. The insulation layer is polycarbonate A transparent conductive material film is provided on the outer surface of the plate to provide a second electrode. This detector It can be installed inside the folder. The holder has electrical connections and optical controls to protect the electrodes. and give.

An electronic circuit is connected to the sample holder and applies a controlled high voltage of 3000V. 2 electrodes, each with a current-voltage gain stage and a gate integration stage. It was connected to 32 amplifier circuits with The digital control circuit and connect each integrator one after the other to an analog-to-digital conversion circuit. 1iz6d signals were provided. Additional circuits include SOS and and EO8 signal and a timing signal so that the laser spot is directed perpendicular to the strip. The integrator gating step is applied to the laser spot as it scans across the detector. synchronize to the target position.

The scanning spot was a gated 442 nanometer helium-cadmium laser. 40 microwatt luminance profile of essentially Gaussian, 100 microns wide, 29 m/s at the detector plane, formed by the optical system. Scanned using a hologon element that rotates at a speed It will be done. The detector moves at a speed such that consecutive scans are spaced 170 microns apart. is moved perpendicular to the scanning direction by a motor-driven stage.

The control circuit controls the application of readout voltage to the second electrode, stage movement, and scanning rotation. synchronize the signal to the data acquisition signal and activate the amplification integrator gate to perform the analysis. Digital pixel values were collected from a log-to-digital converter.

The signal trajectory obtained from the current-voltage stage of the eighth amplifier circuit is shown in the graph of Figure 5. 80. Graph 80 crosses strips 11.43.75.107 etc. It shows the current pulses from the charge released by the laser light as the laser beam moves.

The pulses are separated by 190 microseconds determined by the scan rate and each 60 microseconds wide, reflecting the carrier travel time through the channel. child These pulses are integrated to form a pixel signal array. Is it the 12th amplifier circuit? The signal trajectory of the It showed essentially the same shape, except that it was shifted by the delay.

The plate designated as 79J constructed as described above is then It was used to capture the ji. the plate is inserted into the holder below the x-ray source; The object to be imaged was inserted. A voltage of 6 kV is applied to the second electrode on the strip. was applied and the X-ray source was triggered. Then the voltage was lowered to 1kV and the pre- The sheet was inserted into the reader. In the reader, the strip corresponds to connected to an amplifier circuit. A read voltage of 3 kV is applied to the second electrode and the The rate was scanned. The digital signals corresponding to each pixel are collected and displayed. Converted to an array suitable for display in the play monitor. A clear image of the target I could see it.

Another plate of similar configuration, designated 790, is used to capture X-ray images. used. A reversal voltage of −4 kilovolts is applied to the second electrode while the plate were exposed to uniform indoor lighting. The voltage was then disconnected and the lighting removed.

After a few seconds in the dark, the first and second electrodes are connected and the photoconductive layer is Approximately 2 kilovolts were applied and the plate was exposed to an x-ray pattern.

A readout voltage of zero volts crosses the second electrode and one pixel strip in 6 microseconds. Electrodes scanned by a cutting and moving 10 microwatt laser spot was connected to. The shape and size are very similar to those in Figure 5. Similar current pulses were observed and the image could be clearly seen .

Example 2 The detector is configured to provide comparative data with respect to other configurations. glass The plate substrate is pre-coated with a thin bonding layer of chromium and then approximately 0.6 micron vacuum coated with an aluminum layer to a thickness of . The strip electrode pattern is Formed using conventional photoresist and etching techniques. this pattern comprises several sets of strips of different widths and spacings, with each electrode essentially isolated from the periphery of the substrate. accessible. A thin film of aluminum oxide is formed on the aluminum electrode. , one layer of amorphous selenium was deposited to a thickness of 300 microns.

Separately, a sheet of 175 micron thick polyester has a resistance of 30 ohms/square. Prepared with a transparent conductive electrode of indium titanium oxide (TTO) on a surface with It was done. Then, the untreated surface of the polyester is etched with photoadhesion. attached to the board. The sample is then mounted in a holder that provides electrode connections and lighting control. attached.

The strip was connected to an amplifier. Each amplifier has a current-to-voltage transformer for the first stage. an impedance amplifier and a voltage gain and output driver for the second stage; A multi-stage operational amplifier circuit with an additional third stage gate integrator.

In this example, no integrator is used and the current signal is displayed in the group.

A voltage source is connected between the 110 layer and the ground reference, so that the strip and the 11 0 layer through a voltage source. The timing circuit is on the ITO layer surface of the sample. spot from an argon-ion laser at a wavelength of approximately 488 nanometers. The brightness and position of the lights were controlled. The laser beam spot has a roughly Gaussian shape (G3us ssiashape) to a dimension of approximately 95 microns, and the galvanometer hole and acoustic optic. Attached by acoustic-optic element It was done. The laser spot is essentially aligned with the strip electrode at a speed of 0-100 m/s. is scanned at right angles to the range from less than -cent to 100 percent (22 microwatts) Modulated in brightness. The laser beam position and brightness signals are also displayed on the oscilloscope. Ta.

Each is 80 microns wide with 100 micron centerline spacing. Two adjacent strip amplifiers were selected. The remaining strips are grounded Ru. A voltage is applied to the ITO electrode and varies between 1, 3 and 7.0 volts/min across the sample. A Chron electric field was formed. The light spot moves in strips at a speed of 5 to 50 meters per second. I traversed and scanned.

The current signals from the two strips showed a satisfactory time offset from each other. signal The duration of traversing the selenium layer is confirmed by carrier migration time calculations. It varied satisfactorily with the electric field. From this, the signal from each strip is Insulation installed in the area formed by the light spot width and strip spacing It was found that this corresponds to carriers released into the selenium layer adjacent to the layer.

Spot velocity of 28 meters per second and electric field of 1.5 ports/micron in the selenium layer An example of a signal from one scan using is shown in graph 90 of FIG.

Lines 92 and 94 are two adjacent lines separated by a 20 micron gap. For an 80 micron wide strip, microamperes versus microseconds as a function of time. represents the current. Line 98 has a diameter of 95 with a strip traversal time of 3.6 microseconds. It represents the calculated value of the light intensity irradiating the second strip from the micron spot.

Dotted line 96 shows the Gaussian scanned light spot and the 16 microsecond initial (electric field) depending on the electrostatic model for carriers radiated by carrier travel time and Therefore, it represents the expected current.

Even if the spot moves over several strips during carrier movement on each strip, The data show a well-formed current signal from each strip, even across the . The electric field guides carriers through the photoconductive insulating layer with small transverse velocity, causing carrier movement. The resulting change in charge induced on the strip as Ru. Also, surprisingly, the interaction of currents within adjacent strips is more appropriate. The results were consistent with calculations based on electrostatic induced charge calculations (not based on electrodynamic calculations).

Example 3 The detector was constructed according to these techniques, but with an electrical grid as shown in Figure 7. Four interconnects each surrounded by a wide electrode attached to a land It consisted only of electrode strips. Detector 100 has a 380 micron wide actuating current. a microstrip 102, a 780 micron wide working electrode strip 106, and an 80 micron wide working electrode strip 106. A working electrode strip 108 is provided as shown in FIG. Each working electrode strip 102 ．． 106, and 108 are adjacent grounds by a 20 micron gap. separated from the pad. Detector 100 includes a fourth working electrode strip 104.

This strip 104 consists of 8 strips, each separated from its neighbor by a 20 micron gap. This embodiment has three interconnected 80 micron strips, thereby providing wide ground pads spaced 20 microns on each side from adjacent ground pads for Form another single 780 micron wide electrode. This pattern is on a glass substrate Fabricated in thin (600 nanometer) aluminum. And about 300 A micron-thick layer of amorphous selenium follows, followed by a blocking layer formed over the strips. accomplished. Then, a 175 micron thick polyester insulation layer is attached by photo-bonding. is deposited on amorphous selenium, and this layer is made of translucent indium-titanium. coated with an oxide layer. The detector structure then provides electrical connections and optical control. holder.

A high positive voltage is applied to the indium-titanium-oxide electrode and is applied across the selenium layer. The detector generates an initial electric field of approximately 10 volts/micron with an acceleration of 70 kV peak. The tungsten anode was exposed to an X-ray radiation flux of approximately 8 milliroentgen at a voltage. .

Half of the detector was protected by a heavy lead seal during X-ray exposure.

For readout, the electronic circuit is connected to the sample holder and exposed to about 5 volts in selenium. A controlled high voltage sufficient to produce a micron electric field is applied to the second (semi-transparent) applied to the electrode plane, in an amplifier circuit comprising a current-voltage stage and a gate integration stage. Provided for installation of interconnected electrodes. Digital control circuit integrates stage gate, connect the integrator to an analog-to-digital conversion circuit, and make sure that the laser spot is Integrator gating procedure to scan across the detector in a direction perpendicular to the strip gave a timing signal to synchronize the position of the laser spot.

The scanning spot is scanned by an optical system using an argon ion beam with a wavelength of 488 nanometers. The laser beam focuses on an essentially 85 micron wide brightness profile. passed through the strip at a speed of about 1 m/sec by refraction by a galvanometer mirror. and modulated by holes and acoustic-optic elements. inspection The detector is a motor-driven device that moves at a speed spaced in successive scans with 85 micron separations. It was moved perpendicular to the scanning direction by a motion stage. Control circuit stage movement, laser gate opening operation, and application of readout voltage to the second electrode. Activates the width integral gate to obtain digital pixel values from the analog-to-digital converter. synchronized to the data acquisition signal used to collect.

Figures 8 and 9 show the resulting signal as a function of position perpendicular to the strip. show. Similar curves interconnect adjacent strips to form strips of different widths generated by. Graph 110 of FIG. 8 shows a plate exposed to an X-ray flux. It shows the signal strength for the area. electrode strips 112, 114, 116, and The signals for peaks 112, 114, 116 and 118 are respectively 118. Graph 110 shows that the laser passes over the edge of the strip. When the signal shows exaltation. The shape of the beak 116 (relative to the electrode strip 106) ) shows that the signal strength decreases when the laser enters the central region of the strip. It shows.

The shape of the beak 114 allows the segmented but interconnected electrode strips 104 to form the same waveform. behaving similarly to a solid electrode having a length, e.g., electrode strip 106; is made clear. Therefore, a narrow strip alone will not cause signal enhancement. stomach. Rather, what is required is that the narrow strips, like electrode strips 108, be fixed. It is read out by comparing it with an adjacent electrode which is held at a certain potential.

Graph 120 in FIG. 9 shows the strips for areas of the plate that were not exposed to the The signal strength is shown as a function of position perpendicular to . Electrode strip 102.104.1 The signals for 06, and 108 have peaks 122.124.126, and 1 28, respectively. The four peaks of graph 120 in FIG. 9 and When compared with the four peaks in graph 110, it can be seen that the peak in Figure 9 is higher. Karu. This indicates that exposure to the X-ray flux reduces the signal intensity.

The signal from each strip is 1 or Provides information from pixels larger than 85 microns. Therefore, the mutual ratio For comparison, it is necessary to integrate the signal as shown in FIG. By multiplying the integrated signal strength by /W, this integrated signal becomes 85 There is a need to standardize to micron pixel widths. Here, W is in microns The strip width is . The results of this analysis are shown in graph 130 of FIG. Figure 1 At 0, the (normalized) signal intensity is plotted compared to the strip width. .

The signal strength for the working electrode strip is represented by a circle.

Graph 130 shows that as the electrode strip width decreases from 1580 to 80 microns , shows that the signal strength increases by a factor of 2. This fruit Within the data accuracy of our experiments, our calculations for detectors with these dimensions (shown as line 132 in FIG. 10).

6 2QO4t)t) 1,6 (313Qo 1001:) Time (microseconds) Da Otsu 44. Otsu β0 / ρO 21) 0. 256 jOO35 Otsu 21) l) 250 3Dt) 35tJ position (arbitrary unit) 266t) strip width (microns) Continuation of front page (81) Designated countries EP (AT, BE, CH, DE.

DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), 0A (BF, BJ, CF, CG, CI, CN3. GA, GN, ~fL, MR, NE, SN.

TD, TG), AT, AU, BB, BG, BR, CA.

CH, CZ, DE, DK, ES, FI, GB, HU, JP, KP, KR, LK, LU, MG, blN, MW, NL, NO, NZ, PL, PT, RO, RU, SD, SE.

SK, UA.

(72) Inventor Botts, John E. United States 55133-3427 Mi St. Paul, Nesota, Post Office Box 33427 (front of street address) (No indication) (72) Inventor Horeck, Henry Vee United States of America 55133-34 27 St. Paul, Minnesota, Post Office Box 33427 (No. (no ground indicated)

Claims (18)

[Claims] 1. resulting in an image formed by radiation incident on an imaging device It is a system that allows (a) a first conductive layer, an insulating material, a photoconductive insulating layer, an electrically blocking layer; two conductive layers, the second conductive layer comprising at least one group of conductive layers located in the first direction. An image consisting essentially of a single segmented array of elongated strip-like conductive electrodes. servicing device, (b) an electric field forming means for forming an electric field between the first and second conductive layers; 1 incident radiation causes first charge carriers to be formed within the imaging device. after which the first charge carriers are separated to form a first current, resulting in to form a latent image due to static electricity near the interface between the insulating material and the photoconductive insulating layer. an electric field forming means; (c) a second current in the imaging device that includes a second charge carrier; a scanner that utilizes a second incident radiation in a first time-ordered pattern to cause , (d) for the movement of said second charge carriers connected to and within each electrode; (e) the scanner is arranged in the first direction and in the actual direction; scanning the array in a qualitatively different second direction; (f) Each conductive electrode is addressed in a second time-ordered pattern, one group at a time. While only one of the electrodes is monitored for the movement of the charge carriers, Adjacent electrodes in the group remain measured and vertical compared to the monitored electrode. The electronic circuit is held at a voltage level representing direct ground, and the electronic circuit is shaped by the radiation. the coincidence of the first and second patterns as one pixel of the image formed the system, wherein the pixels represent corresponding portions of the latent image. 2. The system of claim 1, wherein the first and second directions are substantially perpendicular to each other. stem. 3. 2. The insulation material of claim 1, wherein the insulation material is a fluid at the operating temperature of the system. system. 4. 4. The system of claim 3, wherein the fluid insulation is a gas. 5. 5. The system of claim 4, wherein the gas insulating material is air. 6. The insulating material is a material that is a non-fluid fluid at the operating temperature of the system. 2. The system of claim 1, wherein the system is one layer of. 7. The first conductive layer and the insulating material are each semitransparent, and the second radiation is , is incident on the first conductive layer before being incident on the insulating material, and the insulating material is 2. The system of claim 1, wherein the system is stationary before entering the layer. 8. The electrode of the second conductive layer is semi-transparent, and the second radiation is transmitted to the photoconductive insulator. The imaging device passes through the array of conductive electrodes before being absorbed into the layer. 2. The system of claim 1, wherein the system activates a chair. 9. More than one pixel of the electrostatic latent image is illuminated by an intensity-modulated laser. 2. The array is made within a single strip when measured in the second direction. The system described. 10. 2. The system of claim 1, wherein the second radiation is a continuous laser. 11. 2. The first and second radiations of claim 1, wherein the first and second radiations have substantially different wavelengths. system. 12. 2. The first and second radiations have substantially the same wavelength. system. 13. The first radiation is X-ray radiation, and each electrode has a diameter of about 10 to 200 microns. 2. The system of claim 1, wherein the system has a width of . 14. 2. The second radiation is an ultraviolet ray, a visible ray, or an infrared ray. system. 15. Claim: wherein the width of each electrode has a width substantially less than the thickness of the photoconductive layer. The system according to item 1. 16. 2. The width of the electrode is less than the corresponding dimension of one pixel. system. 17. All electrodes have the same number of channels as the number of electrode groups. A signal that is interconnected in a pattern that allows switching to a single signal with The system according to claim 1. 18. The first and second patterns are formed by one electrode of the divided array. 1. The electronic signal is established from the electronic signal due to charge carrier movement when detected by the The system described.