JP2010182642A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which can effectively remove residual electric charge on a photoelectric conversion film and has high image quality, high performance, and high reliability. <P>SOLUTION: The imaging device has a discharged electron beam expansion means for extending electron beams discharged from an electron discharge source array. A controller for performing point progress scanning control makes the electron discharge source array discharge electron beams during a blanking period excluding an output period of an image signal, and extends the electron beam discharged from the electron discharge source array by controlling the discharged electron beam expansion means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image pickup device including an image pickup element having an electron emission source array in which electron emission sources are arranged and a photoelectric conversion film, and a scanning drive circuit for scanning and driving the electron emission source array.

  There has been proposed an imaging apparatus including an electron emission source array in which electron emission sources for extracting electrons by applying an electric field are arranged in a matrix, and a photoelectric conversion film. For example, as an electron emission source (cold cathode electron source), a high-efficiency electron emission device (HEED) (for example, Non-Patent Document 1) or a Spindt type cold cathode array has been proposed (for example, Patent Document 1). ). For example, HEED has a feature that it can be driven at a low voltage and has a simple structure, and application research to an imaging device is underway. Moreover, as a photoelectric converting film, there exists a HARP (High-gain Avalanche Rushing amorphous Photoconductor) photoelectric converting film, for example.

  However, when a high-luminance image is incident (that is, when the amount of incident light is large), there is too much hole charge accumulated in one pixel area of the photoelectric conversion film, and the amount of emitted electrons at the time of image information readout is There is a problem that the accumulated holes are insufficient to neutralize the accumulated holes and the accumulated holes remain.

  In addition, problems caused by defective pixels in the cold cathode array, for example, pixels that do not emit electrons (the amount of emitted electrons is almost zero) or pixels that emit an insufficient amount of electrons (electron emission source), There was a problem that holes remained in the pixel area. In such a case, even if additional electron emission driving for neutralizing the residual holes is performed, the residual holes cannot be eliminated. Further, if the photoelectric conversion film is left in an excessive hole state, problems such as dielectric breakdown may occur.

Pioneer R & D magazine, Vol.17, No.2, 2007, pp.61-69

Japanese Patent Laid-Open No. 7-94075

  The present invention has been made in view of the above points, and the object of the present invention is to achieve high image quality, high performance, and high reliability capable of effectively removing the residual charge of the photoelectric conversion film. One example is to provide an imaging apparatus.

  An image pickup apparatus according to the present invention includes an electron emission source array in which a plurality of electron emission sources are arranged in a matrix, a photoelectric conversion film arranged to face the electron emission source array, and a scanning driver for driving the electron emission source array. And a controller that controls the scanning driver to perform dot-sequential scanning for each scanning line of the electron emission source array, and a part of the electrons emitted from the electron emission source array toward the photoelectric conversion film is incident upon light incidence. An imaging device for obtaining a photoelectric conversion film current flowing by combining with holes generated in a photoelectric conversion film as an output of an image signal, and an emission electron beam expansion means for expanding an electron beam emitted from an electron emission source array Have. The controller emits an electron beam from the electron emission source array in a blanking period other than the output period of the image signal, and controls the emitted electron beam expanding means to expand the electron beam emitted from the electron emission source array.

  The emitted electron beam expanding means includes an intermediate electrode provided between the electron emission source array and the photoelectric conversion film, an intermediate electrode voltage generator for applying a voltage to the intermediate electrode, and a magnet for focusing the electron beam. The controller can adjust the voltage applied to the intermediate electrode to expand the electron beam.

  The emitted electron beam expanding means includes a focusing electrode for focusing the electron beam emitted from the electron emission source array, and the controller adjusts a voltage applied to the focusing electrode so as to expand the electron beam. can do.

  Further, the controller causes the electron beam to be emitted from the electron emission source corresponding to at least one scan line scanned before the scan line from which the image signal is output in the blanking period.

It is sectional drawing which shows typically the structure of a HEED cold cathode HARP image sensor. FIG. 2 is a block diagram showing a configuration of a HEED cold cathode array, a Y scan driver and an X scan driver that drive the HEED cold cathode array, and a controller that controls the entire apparatus. It is a figure explaining the structure of an active drive type HEED cold cathode array, Comprising: It is a fragmentary sectional view which shows a pixel part typically. 1 is a diagram schematically illustrating a configuration of an imaging apparatus according to Embodiment 1. FIG. 3 is a flowchart illustrating a control procedure for performing an imaging operation and a residual charge removal operation according to the first exemplary embodiment. It is a figure which shows typically the operation | movement in the case of scanning the electron emission element of the said scanning line dot-sequentially by the scanning drive of the X direction (horizontal direction) in the scanning line Yj, and the timing of an additional electron emission operation. It is a figure which shows typically the timing in the case of dividing a pixel of a scanning line into a plurality of blocks B1, B2,. FIG. 6 is a diagram schematically illustrating a configuration of an imaging apparatus according to a second embodiment. 7 is a flowchart illustrating a control procedure for performing an imaging operation and a residual charge removal operation of Example 2. It is a figure which shows typically the structure of the electrode for focusing. It is a figure which shows typically the structure of the electrode for focusing. FIG. 6 is a diagram schematically illustrating a configuration of an imaging apparatus that is a modification of the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, substantially the same or equivalent components or parts are denoted by the same reference numerals.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a HEED cold cathode HARP image sensor 10. A HEED cold cathode HARP imaging device (hereinafter also referred to as a cold cathode imaging device) 10 includes an active drive HEED (High-efficiency Electron Emission Device) cold cathode array, a HARP (High-gain Avalanche Rushing amorphous Photoconductor) photoelectric conversion film, It is an image sensor combining the above. More specifically, the cold cathode imaging device 10 includes a HARP photoelectric conversion film 11, a HEED cold cathode array chip 24, and a mesh electrode (intermediate electrode) 15 disposed between the HARP photoelectric conversion film 11 and the HEED cold cathode array 20. have. As will be described later, the HEED cold cathode array chip 24 includes an active drive type HEED cold cathode array (hereinafter simply referred to as a HEED cold cathode array) 20, a Y scan driver 22 and an X scan driver 23 (not shown). Are integrally formed. In addition, although the case where a photoelectric conversion film having a HARP structure is used as the photoelectric conversion film and a cold cathode array having a HEED structure is used as the cold cathode array will be described, these are merely examples, and photoelectric conversion films having other configurations The present invention can also be applied to the case where a Spindt-type cold cathode array or the like is used.

As shown in FIG. 1, the HARP photoelectric conversion film 11 is formed on a translucent conductive film 12, and the translucent conductive film 12 is formed on a translucent substrate 13. The HARP photoelectric conversion film 11 is composed mainly of amorphous selenium (Se), but other materials such as silicon (Si), lead oxide (PbO), cadmium selenide (CdSe), gallium arsenide. A compound semiconductor such as (GaAs) can also be used. The translucent conductive film 12 can be formed of a tin oxide (SnO ₂ ) film, an ITO (indium tin oxide) film, or the like. As will be described later, a predetermined positive voltage (hereinafter also referred to as a HARP potential or a HARP voltage) is applied to the translucent conductive film 12 via a connection terminal (input / output terminal) T1 provided in the glass housing 10A. Is done.

The translucent board | substrate 13 should just be formed with the material which permeate | transmits the light of the wavelength which the cold cathode image pick-up element 10 images. For example, in the case of imaging with visible light, it is made of a material such as glass that transmits visible light, and in the case of imaging with ultraviolet light, it is formed of a material such as sapphire or quartz glass that transmits ultraviolet light. In the case of imaging with X-rays, it may be made of a material that transmits X-rays, such as beryllium (Be), silicon (Si), boron nitride (BN), aluminum oxide (Al ₂ O ₃ ), or the like. That's fine.

  The mesh electrode 15 is provided with a plurality of openings and is made of a known metal material, alloy, semiconductor material, or the like. A predetermined positive voltage (hereinafter also referred to as mesh voltage or mesh potential) is applied to the mesh electrode 15 via the connection terminal T5. The mesh electrode is an intermediate electrode provided for electron acceleration and surplus electron recovery.

  Although the HEED cold cathode array 20 will be described in detail later, the gate electrode of a MOS (Metal Oxide Semiconductor) transistor that drives the HEED is connected to an X scan driver 23 (horizontal scan circuit), and the source electrode (S) is Y scanned. Connected to a driver 22 (vertical scanning circuit), dot sequential scanning is performed. The Y scan driver 22 and the X scan driver 23 are configured as one chip integrally with the HEED cold cathode array 20 on the HEED cold cathode array chip 24, and are provided in the glass housing 10A (not shown). Signals, voltages, and the like necessary for driving the HEED cold cathode array chip 24 are supplied through connection terminals (input / output terminals) T2, T3, and T4 provided in the glass housing 10A.

  All these components are vacuum sealed in a glass housing 10A sealed with frit glass or indium metal.

  In addition, as a method of focusing the electron beam emitted from the cold cathode array 20 on the surface of the HARP photoelectric conversion film 11, for example, a method using magnetic field focusing in which a permanent magnet or the like is arranged around the cold cathode imaging device 10 ( Magnetic field focusing method). In addition, there is a method (electric field focusing method) in which a focusing electrode is provided around an electron emission portion (emission site) of the cold cathode imaging device 10 and an electron beam is focused by adjusting an applied voltage to the focusing electrode.

  FIG. 2 is a block diagram showing the configuration of the HEED cold cathode array 20, the Y scan driver 22 that drives the HEED cold cathode array 20, the X scan driver 23, and the controller 25 that controls the entire apparatus. The Y scan driver 22 and the X scan driver 23 are configured as one chip as the HEED cold cathode array chip 24. The controller 25 and other circuits described later may be provided on the chip.

  As schematically shown in FIG. 2, the HEED cold cathode array 20 is a HEED cold cathode array in which cold cathode electron-emitting devices (hereinafter also referred to as pixels) are arranged on a drive circuit LSI formed on a Si wafer. Is configured as an active drive type field emission array (FEA) that is directly stacked and integrated, and is capable of high-speed driving of an imaging operation in which dot sequential scanning is performed (for example, the drive pulse width of one pixel is several tens of ns). Can respond. The HEED cold cathode array 20 has n rows and m columns connected to scanning drive lines (hereinafter simply referred to as scanning lines) of n lines and m lines in the Y direction (vertical direction) and the X direction (horizontal direction), respectively. It is composed of a plurality of pixels (electron-emitting devices) 30 in a matrix arrangement (number of pixels is n × m). For example, it is configured as a high-definition HEED cold cathode array having 640 × 480 pixels (VGA standard).

  The Y scanning driver 22 and the X scanning driver 23 perform dot sequential scanning and pixel (based on control signals such as a vertical synchronization signal (V-Sync), a horizontal synchronization signal (H-Sync), a clock signal (CLK), etc.) from the controller 25. The electron-emitting device 30 is driven. That is, scanning lines (Yj, j = 1, 2,..., N) are sequentially scanned in the Y direction, and scanning lines (Xi, i = 1) are selected in the X direction when a certain scanning line (Yk) is selected. , 2,..., M) are sequentially scanned and each pixel on the scanning line (Yk) is selectively driven to execute dot sequential scanning.

  FIG. 3 is a diagram for explaining the structure of the active drive type HEED cold cathode array 20, and is a partial sectional view schematically showing an enlarged pixel portion. In the HEED cold cathode array 20, a drive circuit 40 composed of a MOS transistor array and a Y scan driver 22 and an X scan driver 23 that drive and control the drive circuit 40 are formed, and then a HEED portion 31 is formed above the drive circuit 40. Has been.

  As shown in FIG. 3, the HEED portion 31 includes a lower electrode 33, a silicon (Si) layer 34, a silicon oxide (SiOx) layer 35, for example, an upper electrode 36 made of tungsten (W), and a carbon (C) layer 37. This is a MIS (Metal Insulator Semiconductor) type cold cathode electron emission source having a structure. The upper electrode 36 of the HEED cold cathode array 20 is common to all the electron-emitting devices 30, and the lower electrode 33 and the Si layer 34 are divided to electrically separate the electron-emitting devices 30.

  The lower electrode 33 of the HEED portion 31 is connected to the drain electrode D of the MOS transistor 21 of the drive circuit 40 via a via hole. Further, as described above, the gate electrode G and the source electrode S of the MOS transistor are connected to the X scan driver 23 and the Y scan driver 22. Switching of the pixel (electron-emitting device) 30 is performed by controlling the drain potential of the MOS transistor, that is, the potential of the lower electrode 33 of each electron-emitting device 30 in the HEED portion 31.

The number of pixels of the HEED cold cathode array 20 is, for example, 640 × 480 pixels (VGA), and the size of one pixel is 20 × 20 μm ² . An emission site ES that is an opening for electron emission is provided on the surface of the electron emitter 30. For example, FIG. 2 shows a case where 3 × 3 emission sites ES (1 μmφ) having a diameter DE of about 1 μm are formed in a region where one electron-emitting device 30 is 8 × 8 μm ^2. Yes. For example, an electron current of several microamperes (μA) is emitted from one emission site ES (emission current density is about 4 A / cm ² ). Note that the numerical values shown in this embodiment are merely examples, and can be appropriately changed and applied according to the apparatus in which the image sensor is used, the resolution, sensitivity, and the like of the image sensor.

[Configuration and operation of imaging apparatus]
FIG. 4 is a diagram schematically illustrating the configuration of the imaging apparatus 50 according to the present embodiment. In this embodiment, the case where the emitted electron beam from the cold cathode array 20 is focused by the magnetic field focusing method will be described. That is, a magnetic field H (indicated by a broken line arrow) by a magnet 20A arranged around the cold cathode image pickup device 10 is applied to the cold cathode image pickup device 10, and the emitted electron beam is focused.

  The imaging device 50 includes an image signal detector 51 and a controller 25 that controls the Y scan driver 22, the X scan driver 23, the image signal detector 51, and the mesh voltage generator 52.

  As shown in FIG. 4, an external power supply circuit is connected to the translucent conductive film 12, and a predetermined positive voltage (HARP voltage) Vharp is applied to the HARP photoelectric conversion film 11, and through the capacitor C1. The HARP signal is configured to be supplied to the image signal detector 51. Further, a mesh voltage (MESH voltage) Vmesh is applied to the mesh electrode 15 from the mesh voltage generator 52. Further, a predetermined positive voltage (HEED drive voltage) Vd is applied to the upper electrode 36 of the HEED portion 31. That is, the predetermined positive voltage Vd applied to the upper electrode 36 is an extraction voltage for extracting electrons from the electron-emitting device 30 (electron emission source). The mesh voltage Vmesh is a positive voltage with respect to the extraction voltage Vd of the electron emission source. Examples of these voltage values are Vharp = 1.5 kV, Vmesh = 470 V, and Vd = 23 V, but are not limited to these values.

  Next, the operation of the imaging device 50 will be described. When light from the outside enters the HARP photoelectric conversion film 11 through the translucent conductive film 12, electron / hole pairs corresponding to the amount of incident light are generated inside the film near the translucent conductive film 12. Among these, holes are accelerated by a strong electric field applied to the HARP photoelectric conversion film 11 through the translucent conductive film 12 and collide with atoms constituting the HARP photoelectric conversion film 11 one after another to form new electron / hole pairs. Produce. In this way, the avalanche-multiplied holes are accumulated on the side of the HARP photoelectric conversion film 11 facing the HEED cold cathode array 20 (opposite side of the translucent conductive film 12), and the holes corresponding to the incident light image. A pattern is formed. A current when the hole pattern and the electrons emitted from the HEED cold cathode array 20 are combined is output as a HARP current signal (image signal SV) corresponding to the incident light image.

  Note that each component of the imaging device 50 including the Y scan driver 22, the X scan driver 23, the image signal detector 51, the mesh voltage generator 52, and the controller 25 operates based on (synchronously) the clock signal (CLK). Then, various operations such as control of each component described here, detection of various signals, driver driving, and signal processing are performed.

  FIG. 5 is a flowchart showing a control procedure for performing an imaging operation and a residual charge removal operation which are executed under the control of the controller 25. FIG. 6 shows a case in which the electron-emitting devices 30 (1 to m, m = 640 are shown) of the scanning line are dot-sequentially scanned by scanning driving in the X direction (horizontal direction) on the scanning line Yj. The timing of the operation and the additional electron emission operation is schematically shown.

  First, dot sequential scanning is performed for the scanning line Yj (j = 1 at the start of the video frame) (step S11, effective horizontal image period in FIG. 6), and an image signal is output (image signal output period). When the controller 25 determines that the effective horizontal image period is over and is a blanking period (hereinafter referred to as a blanking period) (step S12), the mesh voltage Vmesh is a voltage value in the effective horizontal image period. (Step S13). That is, the mesh voltage Vmesh is changed so that the electron beam to the surface of the HARP photoelectric conversion film 11 is expanded (the beam spot on the surface of the HARP photoelectric conversion film 11 is expanded). In other words, by changing (increasing or decreasing) the mesh voltage Vmesh from the optimum value at which the electron beam is most focused, the electron beam is naturally expanded. For example, the electron beam can be expanded by reducing the positive mesh voltage Vmesh from the voltage value in the effective horizontal image period. That is, the mesh electrode 15, the mesh voltage generator 52, and the magnet 20A that generates the magnetic field H function as an emitted electron beam expanding means.

  The controller 25 performs additional electron emission of the electron-emitting devices 30 of at least one scan line of the HEED cold cathode array 20 in the blanking period after scanning the scan line (Yj) (step S14).

  Thus, the amount of emitted electrons is reduced by changing the mesh voltage Vmesh from the voltage value at the time of normal image signal reading so that the electron beam emitted from the electron-emitting device 30 expands (defocuses the beam). Removal of holes remaining in the pixel area of the HARP photoelectric conversion film 11 corresponding to the defective pixel by additional electron emission from the pixel (cold cathode element) 30 around the defective pixel which is insufficient or has no electron emission. Can do. In other words, when holes remain in the pixel area of the photoelectric conversion film due to the defective electron-emitting device, the residual holes cannot be eliminated even if additional electron emission driving of the defective electron-emitting device is performed. According to the example, it is possible to remove the remaining holes by enlarging the emitted electron beam spot and causing the emitted electrons from the surrounding electron-emitting devices to reach the pixel area corresponding to the defective electron-emitting device (pixel). .

  After the scanning of the scanning line is completed, the process proceeds to the next scanning line (step S11), and the above procedure is repeated. When the imaging operation is finished (step S15), this routine is finished.

  Note that the scanning line for performing additional electron emission (the at least one scanning line) may be an arbitrary scanning line, but is preferably at least one scanning line scanned before the scanning line (Yj). . This is to prevent the holes to be read out from being lost due to the electrons previously entering the pixel area of the photoelectric conversion film from which the image signal is not read out. Further, since residual holes in the surrounding pixel area are removed by the expansion of the electron beam, it is preferable to perform additional electron emission over a plurality of scanning lines. Furthermore, it is preferable that the scanning line for performing additional electron emission is a scanning line (Y (j−k)) (k is an integer of 2 or more) at least a plurality of lines before the scanning line (Yj).

  In the above description, the case where all the pixels (electron-emitting devices) of at least one scan line are simultaneously discharged with additional electrons in the blanking period has been described. However, as shown in FIG. It may be divided into B1, B2,..., Bj, and may be driven to emit additional electrons for each block within the blanking period. By driving in this way, the emission electron current and the neutralization current can be reduced, so that the load such as the HEED cold cathode array 20 and the HARP power supply (Vharp) can be reduced.

  Further, the case of performing additional electron emission in the horizontal blanking period has been described as an example, but the present invention can also be applied to the case of performing vertical blanking. In other words, additional electrons may be emitted during the vertical blanking period.

  FIG. 8 is a diagram schematically illustrating the configuration of the imaging device 50 according to the second embodiment. In this embodiment, a configuration for focusing an electron beam by an electric field focusing method is used. That is, a method of focusing the electron beam by adjusting the voltage applied to the focusing electrode of the cold cathode array 20 is used.

  More specifically, as shown in FIG. 8, a focusing electrode 38 is provided around the electron emission portion (emission site ES) of the emission electron device 30 of the cold cathode array 20. Further, the focusing voltage 38 is supplied from the focus voltage generator 53 to the focusing electrode 38. The focus voltage generator 53 operates under the control of the controller 25. In this embodiment, residual charges are removed by the focusing electrode 38 and the focus voltage generator 53, which will be described in detail below with reference to the flowchart shown in FIG.

  The focusing electrode 38 can be provided around the electron-emitting device 30 as shown in the top view of the cold cathode array 20 in FIG. Alternatively, as shown in FIG. 11, each of the emission sites ES of the electron-emitting device 30 can be provided so as to surround the emission site ES. Note that the configuration of the focusing electrode 38 such as shape and position is not limited to these, and it is only necessary that the emitted electrons can be focused (and defocused) by an electric field.

  FIG. 9 is a flowchart showing a control procedure for performing an imaging operation and a residual charge removal operation which are executed under the control of the controller 25.

  First, dot sequential scanning is performed for the scanning line Yj (j = 1 at the start of the video frame) (step S21, effective horizontal image period in FIG. 6), and an image signal is output. When the controller 25 determines that the effective horizontal image period has ended and it is a blanking period (step S22), the focus voltage Vfocus is changed from the voltage value in the effective horizontal image period (step S23). That is, the focus voltage Vfocus is changed so that the electron beam on the surface of the HARP photoelectric conversion film 11 is expanded (a beam spot is expanded). For example, the focus voltage Vfocus is a negative voltage that repels emitted electrons, and the electron beam can be expanded by increasing the negative focus voltage Vfocus from the voltage value in the effective horizontal image period (or reducing the absolute value). it can. The electron beam spot is naturally enlarged by increasing or decreasing the focus voltage Vfocus from the optimum value at which the electron beam is most focused on the surface of the HARP photoelectric conversion film 11. That is, the focusing electrode 38 and the focus voltage generator 53 function as an emitted electron beam expanding means.

  The controller 25 performs additional electron emission of the electron-emitting devices 30 of at least one scan line of the HEED cold cathode array 20 in the blanking period after scanning of the scan line (Yj) (step S24).

  Thus, the amount of emitted electrons is insufficient by changing the focus voltage Vfocus from the voltage value at the time of reading a normal image signal so that the electron beam emitted from the electron-emitting device 30 is expanded (defocused). By the additional electron emission from the pixels (cold cathode elements) 30 around the defective pixel, holes remaining in the pixel area of the HARP photoelectric conversion film 11 corresponding to the defective pixel can be removed. That is, as in the first embodiment, according to the present embodiment, the emitted electron beam spot is expanded, and the emitted electrons from the surrounding electron emitting devices reach the pixel area corresponding to the defective electron emitting device (pixel). Thus, the remaining holes can be removed.

  After the scanning of the scanning line is completed, the process proceeds to the next scanning line (step S21), and the above procedure is repeated. When the imaging operation is finished (step S25), this routine is finished.

  In addition, it is preferable that the scanning line (at least one scanning line) that emits additional electrons is at least one scanning line scanned before the scanning line (Yj). Further, since residual holes in the surrounding pixel area are removed by the expansion of the electron beam, it is preferable to perform additional electron emission over a plurality of scanning lines. Furthermore, it is preferable that the scanning line for performing additional electron emission is a scanning line (Y (j−k)) (k is an integer of 2 or more) at least a plurality of lines before the scanning line (Yj).

  In the above description, the case where all the pixels (electron-emitting devices) of at least one scan line are simultaneously discharged with additional electrons in the blanking period has been described. However, as shown in FIG. It may be divided into B1, B2,..., Bj and driven to emit additional electrons. By driving in this way, the emission electron current and the neutralization current can be reduced, so that the load such as the HEED cold cathode array 20 and the HARP power supply (Vharp) can be reduced.

  Note that the above-described embodiments can be applied in appropriate combination or modification. For example, an imaging apparatus having a configuration for focusing an electron beam by an electric field focusing method as in the second embodiment can be configured to change the mesh voltage Vmesh to expand the emitted electron beam.

  That is, as a modification of the second embodiment, as shown in FIG. 12, the mesh voltage Vmesh is supplied to the mesh electrode 15 from a mesh voltage generator 55 that is a variable voltage generator. The controller 25 controls to change the mesh voltage Vmesh so that the applied voltage to the focusing electrode 38 of the cold cathode array 20 is fixed and the emitted electron beam from the electron emitting device 30 is expanded.

  Furthermore, even in this case, the emitted electrons from the electron-emitting devices around the scanning line for reading the image signal can reach the pixel area corresponding to the defective pixel (electron-emitting device) within the blanking period. . In this case, all the pixels (electron-emitting devices) of at least one scanning line may emit additional electrons simultaneously, or the pixels of the scanning line are divided into a plurality of blocks so that additional electrons are emitted for each block. You may comprise.

  As described above in detail, by using the beam expanding means for expanding the electron beam emitted from the electron-emitting device 30 in the blanking period, the emitted electrons from the surrounding electron-emitting devices are converted into defective pixels (electron emission). The remaining holes can be removed by reaching the pixel area corresponding to the element.

  Thereby, effects such as improvement of the lifetime of the cold cathode array and suppression of surplus electrons can be obtained. In addition, it is possible to realize a high-quality and high-performance imaging apparatus that is free from white shadow or gradation saturation or is suppressed. Accordingly, the image quality and resolution can be improved, and the reliability and lifetime of the imaging apparatus can be improved.

10 HEED Cold Cathode HARP Image Sensor 11 Photoelectric Conversion Film 15 Mesh Electrode 20 HEED Cold Cathode Array 22 Y Scan Driver 23 X Scan Driver 24 Cold Cathode Array Chip 25 Controller 30 Pixel (Electron Emitting Element)
38 Focusing electrode 31 HEED section 51 Image signal detector 52 Mesh voltage generator 53 Focus voltage generator

Claims (7)

An electron emission source array in which a plurality of electron emission sources are arranged in a matrix, a photoelectric conversion film arranged to face the electron emission source array, a scan driver for driving the electron emission source array, and the scan driver And a controller that performs point-sequential scanning for each scanning line of the electron emission source array, and a part of the electrons emitted from the electron emission source array toward the photoelectric conversion film is incident upon light incidence. An imaging device that obtains a photoelectric conversion film current that flows by combining with holes generated in a photoelectric conversion film as an output of an image signal,
An emission electron beam expanding means for expanding an electron beam emitted from the electron emission source array;
The controller emits an electron beam from the electron emission source array in a blanking period other than the output period of the image signal, and controls the emitted electron beam expanding means to emit electrons emitted from the electron emission source array. An imaging apparatus characterized by expanding a beam. The emitted electron beam expanding means includes an intermediate electrode provided between the electron emission source array and the photoelectric conversion film, an intermediate electrode voltage generator for applying a voltage to the intermediate electrode, and a magnet for focusing the electron beam. And including
The imaging apparatus according to claim 1, wherein the controller expands the electron beam by adjusting a voltage applied to the intermediate electrode.   The applied voltage to the intermediate electrode is a positive voltage with respect to the extraction voltage of the electron emission source, and the controller expands the electron beam by reducing the applied voltage to the intermediate electrode. The imaging device according to claim 2. The emitted electron beam expanding means includes a focusing electrode for focusing an electron beam emitted from the electron emission source array,
The imaging apparatus according to claim 1, wherein the controller expands the electron beam by adjusting a voltage applied to the focusing electrode.   The voltage applied to the focusing electrode is negative with respect to the extraction voltage of the electron emission source, and the controller expands the electron beam by increasing the voltage applied to the focusing electrode. The imaging apparatus according to claim 4, wherein the imaging apparatus is characterized.   The controller emits an electron beam from an electron emission source corresponding to at least one scanning line scanned before the scanning line from which the image signal is output in the blanking period. Item 6. The imaging device according to any one of Items 1 to 5.   7. The controller according to claim 1, wherein the controller divides the pixels of the scanning line into a plurality of blocks and emits an electron beam from an electron emission source for each of the blocks in the blanking period. The imaging device described in 1.

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