JP2021141506A - Imaging system and imaging system application device - Google Patents

Abstract

To provide a compact, lightweight, and color-coded imaging system with excellent environmental performance such as radiation resistance.SOLUTION: A radiation-resistant imaging system includes a sensor unit 10 and an image processing unit 20. The sensor unit 10 includes a color separation element 14 that extracts light having a specific wavelength, and an imaging sensor 15 that captures light transmitted through the color separation element 14. The imaging sensor 15 includes a sensor element 13 and a transmission/reception unit 12. The sensor element 13 includes a light receiving element and a charging transistor for each pixel, includes one or a plurality of threshold value determination circuits for determining whether a terminal voltage of the light receiving element is equal to or higher than a predetermined threshold value, and obtains a plurality of sub-images corresponding to different brightness threshold values. The image processing unit 20 processes signals of the plurality of sub-images to generate a gradation image.SELECTED DRAWING: Figure 1

Description

The present invention relates to an imaging system using an image sensor and an imaging system application device.

Nuclear power plants and radiation utilization facilities are equipped with imaging systems equipped with image sensors to monitor the inside of the plants and facilities. In addition, an imaging system having an image sensor is used for internal investigations for decommissioning a nuclear power plant. Image sensors included in these image pickup systems include an image pickup tube which is a vacuum tube, a solid-state image sensor using a semiconductor, and the like.

As described in Patent Document 1, in a solid-state image sensor type image sensor, a CMOS type amplification amplifier (complementary metal-insulator-semiconductor type field effect transistor) usually converts a charge photoelectrically converted by a light receiving element in a pixel. , CMOS-FET) is used for amplification. The amplified voltage signal is sequentially scanned by a vertical scanning circuit and a horizontal scanning circuit and extracted, and a voltage signal proportional to the amount of light of each image, that is, the brightness is acquired. As a result, an image of the object (subject) is acquired.

However, it is known that CMOS type amplifiers are liable to be deteriorated by irradiation. One reason for this is as follows. When the MOS FET is irradiated with radiation, electrons and holes are generated in the oxide film (insulating film) of the gate. Since the electrons in the oxide film have higher mobility than the holes, they escape from the oxide film, but since the holes have low mobility, they accumulate in the oxide film as positive charges. This is because the electric charge accumulated in the oxide film fluctuates the threshold value of the MOS FET, which causes an adverse effect such as the inability to perform stable signal amplification.

Generally, circuit elements used in a harsh environment such as a radiation environment are shielded with lead or the like, or measures are taken such as keeping them away from a radiation source. However, image sensors, cameras, and image pickup devices cannot be shielded by a lead plate that does not transmit light.

On the other hand, in order to colorize the captured image, a color filter has been conventionally arranged in front of the image sensor as described in Patent Document 2. However, in this case, it is known that the color filter itself deteriorates in a radiation environment such as a decrease in light transmittance, and it is difficult to use the color image pickup device for a long time in a radiation environment.

Japanese Unexamined Patent Publication No. 2014-39159 Japanese Unexamined Patent Publication No. 2018-200909

As described above, the conventional solid-state image sensor type image sensor usually uses a CMOS type amplifier, and the CMOS type amplifier has a problem that its characteristics are easily deteriorated by irradiation.

In order to deal with this problem, attempts have been made to use a vacuum tube such as an image pickup tube, but the image pickup tube is physically large and heavy in principle because it operates by spatially scanning an electron beam. There is a problem.

Further, it is known that when a color filter is arranged in front of an image sensor as described in Patent Document 2 to colorize the color, the color filter itself deteriorates in a radiation environment such as a decrease in light transmittance. There is a problem that the imaging device used in a radiation environment cannot be used for a long time.

On the other hand, in applied devices such as robot systems, there is a demand for mounting a plurality of image sensors, and a compact and lightweight image sensor is required. Further, in robot work support, colorization is required in order to project an imaged object more clearly, instead of a monochrome image such as a conventional CMOS radiation-resistant camera or an image pickup tube using a vacuum tube.

The problem to be solved by the present invention is to provide an image pickup system and an image pickup system application device which are colorized by using a compact and lightweight image sensor and a color separation element, which have excellent environmental performance such as radiation resistance. be.

A typical example of the invention disclosed in the present application is as follows. That is, it is an imaging system including a sensor unit and an image processing unit, and the sensor unit includes a color-separating element that extracts light of a specific wavelength and an imaging sensor that captures light transmitted through the color-resolving element. The image sensor has a sensor element and a transmission / reception unit, and the sensor element has a light receiving element and a charging transistor for each pixel, and determines whether the terminal voltage of the light receiving element is equal to or higher than a predetermined threshold value. Alternatively, it has a plurality of threshold value determination circuits and acquires a plurality of sub-images corresponding to different brightness threshold values, and the image processing unit processes the signals of the plurality of sub-images to generate a gradation image. It is a feature.

According to one aspect of the present invention, it is possible to provide an imaging device and an imaging system that have excellent environmental resistance and can capture colored images even in a harsh environment. Issues, configurations and effects other than those mentioned above will be clarified by the description of the following examples.

It is a block diagram in the radiation-resistant imaging system which concerns on 1st Embodiment of this invention. It is 1st example of the schematic diagram which shows the structure of the color-separating element of 1st Example. It is the 2nd example of the schematic diagram which shows the structure of the color-separating element of 1st Example. It is a schematic diagram which shows the structure of a sensor element. It is a schematic diagram which shows the structure of each pixel. It is a circuit diagram which shows the threshold value determination circuit of this Example. It is a circuit diagram which shows another example of the threshold value determination circuit of 1st Example. It is a schematic diagram which shows the composition of the pixel of the sensor element of the comparative example. It is a timing diagram which shows typically the reading sequence from the pixel in the sensor element of 1st Example. It is a schematic diagram which shows the composition method of the gradation image. It is a logical table which shows the process which comprises the gradation image of 1st Example. It is a circuit diagram of the circuit which realizes the process which comprises the gradation image shown in FIG. It is a schematic diagram which shows the state which image data of the sub image of 1st Example is stored in the memory. It is a truth table for realizing the process of forming the gradation image shown in FIG. It is a figure which shows the structure of the sensor element of 2nd Example. It is a timing diagram which shows typically the reading sequence from the pixel in the sensor element of 2nd Example. It is a schematic diagram which shows the relationship between the amount of light incident on the light receiving element of the 3rd Example, and a terminal voltage. It is a schematic diagram which shows the relationship between the read sequence from each pixel of 3rd Example, and the charge voltage Vb0. It is a schematic diagram which shows the relationship between the read sequence from each pixel of 4th Example, and the charge voltage Vb0. It is a figure which shows the robot system which is an example of the application equipment of 7th Example. It is a schematic diagram which shows the composition of the pixel of 8th Example. It is a schematic diagram which shows the structure of the sensor element of 8th Example.

Hereinafter, examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples, and for example, a plurality of examples can be combined or arbitrarily modified without departing from the technical idea of the present invention.

Further, in the present specification, the same members are designated by the same reference numerals, and duplicate description will be omitted. For the convenience of illustration, the contents of the illustration may be changed from the actual configuration without impairing the gist of the present invention.

FIG. 1 is a configuration diagram of an imaging system 1 of this embodiment.

The image pickup system 1 of this embodiment includes a sensor unit 10 and an image processing unit 20. As shown in the drawing, the sensor unit 10 and the image processing unit 20 may be configured separately and connected by a cable 30 or wirelessly, but the sensor unit 10 and the image processing unit 20 may be integrally configured.

The sensor unit 10 is composed of a color separation element 14 and a plurality of image pickup sensors 15, and the image sensor 15 is a sensor element 13 that detects an external image and a sensor control unit that controls processing by a circuit in the sensor element 13. 11 and a transmission / reception unit 12 for transmitting / receiving a signal between the sensor unit 10 and the image processing unit 20. The sensor control unit 11 and the transmission / reception unit 12 are functionally separated, and the sensor element 13, the sensor control unit 11, and the transmission / reception unit 12 may be provided on one IC chip.

The color separation element 14 is made of an inorganic material (for example, a dielectric optical element) and decomposes visible light into RGB (red, green, blue) having different wavelengths. As shown in the figure, an image containing a specific color (for example, a red light image, a black-and-white image and a red image) is received by a plurality of image pickup sensors 15 and signal processing is performed by the image processing unit 20 in the subsequent stage. Image) and a color image are acquired. Unlike the conventional color separation element using a color filter made of an organic material, the color separation element 14 of this embodiment is made of an inorganic material, so that it is not easily deteriorated by radiation or ultraviolet rays, and is subjected to a harsh environment such as a radiation environment. But it can be used stably for a long time.

More specifically, the configuration of the color separation element 14 is preferably a dielectric optical element. In a dielectric optical element, a plurality of layers of inorganic materials having different refractive indexes are laminated, and light in a specific wavelength band is reflected according to the laminated film thickness. Since the reflection wavelength band is determined by the laminated film thickness, no pattern is required. Since the color separation element 14 of the present invention does not contain an organic substance due to such a configuration, browning (browning) due to irradiation with radiation or ultraviolet rays can be remarkably suppressed as compared with a conventional color filter.

The image sensor 15 may be provided with three corresponding to each of the RGB colors decomposed into the three primary colors of light (red, green, and blue), but the combination may be arbitrarily changed. Further, by using a plurality of image pickup sensors 15, the SN ratio (signal noise ratio) can be improved, and a higher quality image can be provided.

(Structure of color separation element)
FIG. 2 is a schematic view showing a configuration example 1 of the color separation element 14.

In Configuration Example 1, when visible light is incident on the color separation element 14 from the left side of the figure, the visible light is red light, green light, and blue light due to the three dielectric mirrors 16R, 16G, and 16B that reflect each wavelength of RGB. It is decomposed into (RGB). In this example, the red light R is reflected in the positive direction on the x-axis, the blue light B is reflected in the negative direction on the x-axis, and the green light G is reflected in the z-axis direction. The radiation resistance of the image pickup system 1 is further improved by making the γ-rays that are not reflected by the dielectric mirrors 16R, 16G, and 16B travel straight so that the radiation does not directly enter the image pickup sensor 15. In addition, in order to simplify the configuration, the dielectric mirror 16G that reflects green light may be eliminated, and the green light G may be allowed to travel straight as shown in FIG.

Each of the red light, green light, and blue light reflected by the color separation element 14 is received by the image pickup sensor 15. In the illustrated color separation element 14, the red light R and the blue light B are reflected twice, but the green light is reflected only once, so that the green image taken by the green image sensor 15 is flipped horizontally. It becomes the image that was done. For this reason, the green image requires electrical left-right reversal processing in the image processing unit 20. More specifically, in the signal processing by the image processing unit 20 described later, the column numbers of the pixels on the memory schematically shown in FIG. 13 are inverted left and right only for the green image.

A detailed examination of the radiation degradation of conventional color filters revealed that the color filters cause browning, which reduces the visible light transmittance. As a result of diligently examining the cause of browning due to this irradiation, the inventors of the present invention have come to the conclusion that the organic substances contained in the color filter are decomposed by irradiation with light having high photon energy such as γ-rays. ..

Generally, the binding energy between carbons forming the skeleton of an organic substance is about 4 eV (electron volt) for a single bond and about 6 eV for a double bond, so light with a wavelength of 20 nm or less, that is, photon energy of 60 eV or more is emitted. When irradiated, the bond breaks. Therefore, when the organic substance is irradiated with radiation (generally, the wavelength is 20 nm or less, that is, the photon energy is 60 eV or more), the organic substance is decomposed and browning occurs.

In such browning, even when a color filter whose main constituent material is an inorganic material is used, even if residual organic substances of the chemicals used in the lithography process used when patterning the color filter for each color remain. It can occur. This is the reason why conventional color filters deteriorate when they are irradiated with radiation.

Based on these considerations, in the examples of the present invention, a color-separating element containing no organic matter, that is, a color-separating element 14 made of an inorganic material was adopted.

Further, in order to solve the problem of residual chemicals in the patterning process of each color of the filter, it is preferable to use a color separation element that does not use the patterning process.

FIG. 3 is a schematic view showing a configuration example 2 of the color separation element 14.

In Configuration Example 2, as the color separation element 14, a filter made of an inorganic material, particularly a half mirror 17, and a color filter 18 that transmits light in a desired wavelength range are used.

The half mirror 17 is a mirror that reflects a certain amount of light and transmits a certain amount of light without having wavelength selectivity in the visible light wavelength range.

The incident light transmitted through the lens optical system is divided into reflected light and transmitted light by the half mirror 17. A color filter 18 is arranged in the path of the reflected light, and the light transmitted through the color filter 18 is imaged by the image sensor 15.

Another imaging sensor 15 is arranged in the path of the transmitted light to capture an image of the transmitted light.

In this embodiment, the color filter 18 is configured to use an inorganic material, and a filter that transmits through the red region is used. For example, by including a metal oxide in a glass material, a filter that transmits only red wavelengths can be constructed.

In Configuration Example 2, it is preferable to use a half mirror 17 composed of a laminated dielectric film. However, if it functions as a half mirror, it is not limited to a half mirror made of a laminated dielectric film.

In Configuration Example 2, since the transmitted light of the half mirror 17 includes all colors, the acquired image is a black-and-white image. On the other hand, the reflected light from the half mirror 17 passes through the red color filter, resulting in a red image. By superimposing and displaying the two images, it is possible to obtain an image in which the red portion of the subject is colored red in the black-and-white image.

In Configuration Example 2, since an image obtained by synthesizing a black-and-white image and a color image of a specific color is obtained, it is possible to take an image in which an object of a specific color is highlighted.

Further, a color image can be obtained by taking a red image, a green image, and a blue image using a plurality of half mirrors 17 and synthesizing them.

Further, in the configuration shown in FIG. 3A, since the reflected light is reflected by the half mirror 17 an odd number of times, the image is horizontally inverted. Therefore, the image acquired from the reflected light may be electrically inverted left and right in the image processing unit 20 and then combined with the transmitted light. In the left-right reversal process, similarly to the above, in the signal processing by the image processing unit 20, the column numbers of the pixels on the memory schematically shown in FIG. 13 may be horizontally reversed only for the green image.

In the configuration shown in FIG. 3B, a reflector 19 is provided after the half mirror 17, and the reflected light is also reflected an even number of times to prevent left-right reversal. If this configuration is used, the left-right inverted image processing becomes unnecessary, so that the processing circuit of the image processing unit 20 can be simplified.

(Structure of sensor element 13)
FIG. 4 is a schematic view showing the configuration of the sensor element 13.

In FIG. 4, four pixels 130 are shown for the sake of clarity. The actual sensor element 13 has a larger number of pixels, and typically has pixels having 100 to 2000 rows and 100 to 4000 columns.

Two horizontal wires and one vertical wire are connected to each pixel.

One of the horizontal wirings is a charging scanning line (Charge scanning line) 135 for charging, and has a function of charging the light receiving element 131 of the pixel 130 as described later. The other horizontal wiring is a read scan line (Read scan line) 136 that specifies a signal read timing. The charging scanning line 135 is connected to the charging address terminal (“CA” in the figure) of each pixel 130. The read scan line 136 is connected to the read address terminal (“RA” in the figure) of each pixel 130. The charging scanning line 135 and the reading scanning line 136 are provided by the number of lines of each pixel 130.

The charging scanning line 135 is connected to a charging scanning circuit (Charge scanning circuit) 138. The read scan line 136 is connected to the read scan circuit 139 (Read scan circuit). The charge scanning circuit 138 and the readout scanning circuit 139 each output an appropriate voltage waveform and scan each pixel 130. This scanning method will be described in detail later.

The vertical wiring is data line 137. The data line 137 is wired to each pixel 130.

The data line 137 is connected to a data output terminal (“D” in the figure) of each pixel 130. The data line 137 has a function of reading a signal detected by the light receiving element 131 in the pixel 130. The data line 137 is connected to the horizontal scanning circuit 140, and sequentially reads out the signals detected by the light receiving element 131 in each pixel 130 and transfers them to the transmission / reception unit 12.

(Pixel composition)
FIG. 5 is a schematic view showing the configuration of each pixel 130.

Each pixel 130 has a light receiving element 131, a holding capacity 132, a charging transistor (Charge transistor) 133, and a threshold value determination circuit 134.

In the drawings representing the schematics described herein, the downward white arrows indicate that they are connected to the ground potential. Here, the ground potential means the reference potential in the sensor element 13, and does not have to match the ground potential of the signal processing unit. If necessary, a bias potential may be applied to the reference potential (ground potential) in the sensor element 13 with respect to the ground potential of the signal processing unit.

In this embodiment, a silicon photodiode may be used for the light receiving element 131, or a silicon carbide photodiode may be used.

The holding capacitance 132 may be provided independently of the light receiving element 131, or the junction capacitance (parasitic capacitance) of the light receiving element 131 may be used.

When a photodiode is used for the light receiving element 131, the equivalent circuit of the junction capacitance of the light receiving element 131 is the same as the holding capacitance 132 of FIG. Therefore, when the junction capacity of the light receiving element 131 has a sufficient capacity as the holding capacity 132, instead of providing the holding capacity 132 separately from the light receiving element 131, the function of the holding capacity 132 may be provided by the bonding capacity. good. In the present specification, the holding capacitance 132 includes the junction capacitance (parasitic capacitance) of the light receiving element 131 as described above.

That is, in the present specification, the holding capacity 132 also includes the junction capacity of the light receiving element 131. The effect of the present invention can also be obtained when the holding capacity 132 is replaced by the bonding capacity of the light receiving element 131.

A method of detecting external light at each pixel 130 will be described with reference to FIG. When an appropriate voltage is applied to the charging scanning line 135 to turn the charging transistor 133 into an ON state (that is, a conductive state), the light receiving element 131 and the holding capacity 132 are charged to the charging voltage Vb0. The charging transistor 133 may be a bipolar transistor or a MOSFET.

In this state, when the light receiving element 131 is not irradiated with light, the terminal voltage of the holding capacity 132 is held. On the other hand, when the light receiving element 131 is irradiated with light, the light receiving element 131 becomes conductive and the charge of the holding capacity 132 gradually leaks out, so that the terminal voltage of the holding capacity 132 decreases.

(Threshold determination circuit 134)
The terminal of the holding capacity 132 is connected to the input terminal IN of the threshold value determination circuit 134.

The threshold value determination circuit 134 outputs the signal 1 from the output terminal O when the terminal voltage of the holding capacity 132 is smaller than the preset voltage threshold value Vth, and outputs the signal 0 from the output terminal O when the terminal voltage is larger than the voltage threshold value Vth. Output. That is, when the brightness of the external subject exceeds a predetermined brightness threshold value Bth, the holding capacity 132 voltage of the pixel 130 at the corresponding position is lowered by the leakage current of the light receiving element 131 and becomes smaller than Vth, so that the threshold value is determined. The circuit 134 outputs 1 as an output signal. On the other hand, when the brightness of the subject is smaller than the luminance threshold Bth, the holding capacity 132 voltage of the pixel 130 at the corresponding position is larger than Vth, so that the threshold determination circuit 134 outputs 0 as an output signal.

The output signal 1 means the signal state 1 of the logic circuit. For example, a high voltage state (High level) is defined as a signal “1”, and a low voltage state (Low level) is defined as a signal “0”. On the contrary, the Low level may be set to the signal "1" and the High level may be set to the signal "0". Alternatively, a current level or the like may be used instead of the voltage level. In this embodiment, the signal "1" is made to correspond to the high level of the voltage.

In this way, the signal "1" is output at the pixel 130 corresponding to the location corresponding to the luminance threshold Bth or higher of the subject, and the signal "0" is output at the pixel 130 corresponding to the luminance threshold Bth or lower. That is, a binary image based on the luminance threshold Bth can be acquired.

Since a binary signal flows through each data line 137, the changeover switch 141 may be a logic circuit.

(Output impedance of threshold value determination circuit 134)
The threshold value determination circuit 134 has a read enable terminal RE (Read Enable). The read enable terminal RE is connected to the read scan line 136. During the period during which the enable signal is input to the read enable terminal RE (read enable period), the signal "0" or "1" is output from the output terminal O according to the above-described operation.

During the period in which the enable signal is not input to the read enable terminal RE (read invalid period), the output terminal O transitions to a higher impedance state. By setting the output impedance of the output terminal O to a high impedance during the read invalid period in this way, even if a plurality of pixels 130 are connected to the data line 137, the output of the threshold value determination circuit 134 of the selected pixel 130 is output. It becomes possible to take out the signal.

(Implementation example of threshold value determination circuit 134)
FIG. 6 is a circuit diagram showing the threshold value determination circuit 134 of this embodiment.

The threshold value determination circuit 134 of this embodiment is composed of a transistor 1 (Tr1) which is a PNP type transistor, a transistor 2 (Tr2) which is an NPN type transistor, and a resistor (R). The input terminal of the threshold value determination circuit 134 is connected to the base of the transistor 2 (Tr2). When the input terminal of the threshold value determination circuit 134 is larger than the threshold voltage Vth of the transistor 2 (Tr2), the collector of the transistor 2 (Tr2) is maintained (latched) at the power supply voltage Vcc. The collector of Tr2 becomes the output terminal of the threshold value determination circuit 134.

The threshold value determination circuit 134 used in this embodiment employs a latch circuit, and the output signal maintains a high level or a low level during the period when the power supply voltage Vcc is applied. As described above, by using the latch circuit for the threshold value determination circuit 134, there is an effect that malfunction can be reduced.

When the voltage of the RE terminal in FIG. 6 is set to the Low level, the two transistors Tr1 and Tr2 are in a non-conducting state, so that the output impedance of the output terminal O is in a high impedance state.

FIG. 7 is a circuit diagram showing another example of the threshold value determination circuit 134.

In the threshold value determination circuit 134 shown in FIG. 7, the operations of the two transistors Tr1 and Tr2 are the same as those in FIG. 6, and the read transistor Tr3, which is a third transistor, is added. The read-out transistor Tr3 is turned on only during the period in which the read-out enablement pulse is applied, and the signal voltage is output to the data line 137. Since the read transistor Tr3 is turned off during the read invalid period, the output impedance of the output terminal O of the threshold value determination circuit 134 becomes higher than that of the circuit of FIG.

It is more desirable to further increase the output impedance of the threshold value determination circuit 134 of the unselected pixels 130 when the number of scanning lines is large. The reason is that since the threshold value determination circuit 134 for the number of scanning lines is connected to each data line 137, the higher the output impedance of the threshold value determination circuit 134 for the non-selected pixels, the larger the number of scanning lines. This is because the impedance of the non-selected pixels by the threshold value determination circuit 134 can be maintained at a sufficient height.

The circuits shown in FIGS. 6 and 7 are examples of the threshold value determination circuit 134, and the effects of the present invention can be obtained by using other circuits as long as they satisfy the characteristics of the threshold value determination circuit 134 described above. Needless to say.

(Comparison with comparative example)
Next, a comparison with a comparative example is performed. FIG. 8 is a schematic view showing the configuration of pixels 530 of the sensor element of the comparative example.

FIG. 8 is an example of a CMOS sensor (complementary MOS field effect transistor type sensor), and shows a method of an imaging device of a consumer camera.

The sensor element shown in FIG. 8 includes a light receiving element 531, a holding capacity 532, and a charging transistor (Charge transistor) FET 1 connected to the charging scanning line 535. The voltage of the holding capacity 532 provided in parallel with the light receiving element 531 charged by the charging scanning line 535 is amplified by the pixel amplifier, and the voltage value V2 proportional to the accumulated charge of the holding capacity 532 is output as an analog signal. A CMOS type FET (field effect transistor) is used for the pixel amplifier. A pixel amplifier is composed of the FET 2 and the FET 3 of FIG. In this pixel amplifier, the FET 2 operates as a source follower circuit, and performs charge amplification that converts the charge applied to the gate of the FET 2 into a low impedance voltage signal.

When an appropriate voltage is applied to the readout scanning line 536 and the FET 3 is turned on, the analog signal voltage, which is the output signal of the pixel amplifier, is output to the data line 537, and is sequentially output by a horizontal scanning circuit (not shown). ..

In the comparative example, since the voltage signal corresponding to the brightness level of the subject is output in an analog manner, it is possible to acquire an image with gradation.

However, since the CMOS pixel amplifier used in the circuit in the pixel of FIG. 8 has low resistance to radiation irradiation, there is a problem that the sensor element tends to deteriorate when used in a harsh environment such as the presence of radiation. On the other hand, in the present invention, since an element having higher resistance to irradiation than a CMOS amplifier is used, there is an effect that deterioration of characteristics in a radiation environment can be suppressed.

In particular, as shown in FIG. 6 of the present embodiment of the present invention, the bipolar transistor is known to have higher radiation resistance than the CMOS FET, and it is more preferable to configure the bipolar transistor.

Further, in the above-mentioned comparative example, the changeover switch and the transmission / reception circuit connected to the data line 537 need to handle an analog signal. On the other hand, in the present invention, the signal processed by the changeover switch 141 and the transmission / reception circuit 142 is a binary signal, so that the circuit configuration is simpler than in the comparative example.

(Gradation of binary image)
As described above, the image obtained by the pixel 130 of this embodiment is a binary image obtained by binarizing the subject with a certain brightness threshold value.

The method of constructing a gradation image from a binary image will be described below. In this embodiment, binary images are acquired with a plurality of luminance thresholds Bth [n], and each of them is referred to as a sub-image SIM [n] (Sub-Image). Here, the subscript n is a number for distinguishing the luminance threshold value from the sub-image, and n = 1, 2, ....

(Means to change the brightness threshold)
A method of changing the luminance threshold value Bth [n] will be described. In the present invention, it is detected whether or not the voltage V1 of the holding capacity 132 exceeds the threshold value. The voltage V1 of the holding capacity 132 is expressed by the following equation.

Here, Vb0 is the charging voltage of the light receiving element 131, ΔV is the amount of voltage decrease due to the light current flowing through the light receiving element 131, J is the current density of the light current flowing through the light receiving element 131, S is the light receiving area of the light receiving element 131, and Δt is the light receiving area of the light receiving element 131. The exposure time of the light receiving element 131, C is the capacitance of the holding capacity 132. In this embodiment, a photodiode is used as the light receiving element 131.

There are the following methods for changing the brightness threshold Bth of the pixel 130.
(A) The exposure time Δt is changed.
(B) The area S of the light receiving element 131 is changed.
(C) The charging voltage Vb0 to the light receiving element 131 is changed.

In the present invention, the brightness threshold value may be changed by any of the methods (A), (B), and (C). Moreover, you may combine these plurality of methods. Further, the brightness threshold value may be changed by a method other than (A) to (C).

That is, the imaging system 1 of this embodiment includes a luminance threshold value changing means. The luminance threshold value changing means includes (A) changing the exposure time Δt for each sub-image, (B) having a plurality of sub-pixels having different light-receiving areas of the light-receiving element 131, and (C) charging voltage Vb0 applied to the light-receiving element 131. There are means such as changing the above for each predetermined period, and further include means for combining these (A) to (C).

Further, the above-mentioned luminance threshold value changing means is typically provided in the sensor unit 10. This is because it is easy to implement. However, it may be provided in addition to the sensor unit.

(Change the brightness threshold depending on the exposure time)
In this embodiment, the brightness threshold is changed by changing the exposure time.

FIG. 9 is a timing diagram schematically showing a reading sequence from the pixel 130 in the sensor element 13 of this embodiment. In this figure, the horizontal axis represents time and the vertical axis represents the scanning line position of the pixel 130 in the sensor element 13. The fact that the diagram representing the scanning timing is an oblique straight line as shown in FIG. 9 indicates that each scanning line is sequentially scanned as the first scanning line, the second scanning line, and so on.

One field is the time for acquiring one image, typically 1/30 second to 1/60 second. In this example, it was set to 1/30 second (33.3 ms). One field is divided into four subfields. Get one sub-image in one sub-field. Although FIG. 9 shows an example of acquiring four sub-images, it may of course be divided into more sub-fields. The nth subfield will be referred to as SF [n].

The read sequence in the subfield will be described by taking the first subfield SF [1] as an example. When the charging scanning pulse is applied to the charging scanning line 135 in the first row, the light receiving element 131 is charged to the charging voltage Vb0 in the pixel 130 in the first row. After that, the charging scanning pulse is applied to the charging scanning lines 135 in the second and subsequent rows.

When a read scan pulse is applied to the read scan line 136 of the first row after the time Δtex has elapsed, the threshold determination circuit 134 of each pixel 130 operates, and the output signal 1 is based on the holding capacity 132 voltage at that time. Alternatively, 0 is output from the threshold value determination circuit 134. After that, the read scan pulse is applied to the read scan lines 136 of the second and subsequent rows. As described above, the time Δtex from the application of the charge scanning pulse to the application of the readout scanning pulse corresponds to the exposure time.

In this way, the scanning of the first subfield SF [1] is completed, and the first subimage SIm [1] is acquired. Next, the charging scanning line 135 and the reading scanning line 136 are similarly scanned in the second subfield SF [2]. However, the elapsed time Δtex between the charging scanning line 135 and the reading scanning line 136 is longer than that of SF [1]. Next, the elapsed time Δtex between the charging scan line 135 and the read scan line 136 is made longer than that of SF [2], and similarly in the third subfield SF [3], the charge scan line 135 and the read scan line 136 are also formed. Is scanned. Further, the elapsed time Δtex between the charging scan line 135 and the read scan line 136 is made longer than that of SF [3], and similarly, in the fourth subfield SF [4], the charge scan line 135 and the read scan line 136 Scan. In this way, the sub-image is acquired by changing the exposure time Δtex for each sub-field.

As can be seen from the mathematical formula (1), when the exposure time Δtex is changed, the luminance threshold value corresponding to the voltage threshold value of the threshold value determination circuit 134 changes. In the case of the same subject, the longer the exposure time Δtex, the lower the holding capacity 132 voltage. Therefore, even if the luminance is smaller (dark luminance), the voltage threshold of the threshold determination circuit 134 is exceeded and the output signal “1” is given. In this way, a plurality of sub-images having different luminance thresholds can be acquired.

(Composition of gradation image)
As shown in FIG. 1, the acquired plurality of sub-images are transmitted from the sensor unit 10 to the image processing unit 20. The image processing unit 20 composes a gradation image from a plurality of sub-images having different luminance thresholds by the following method.

FIG. 10 is a schematic diagram showing a method of constructing a gradation image. FIG. 10 shows an example of constructing a gradation image of four gradations from four sub-images.

FIG. 10A shows four sub-images. Each sub-image is a binary image showing an image of the subject, the first is a sub-image with a brightness threshold of 8, the second is a sub-image with a brightness threshold of 4, and the third is a sub-image with a brightness threshold of 2. The fourth image is a sub-image having a brightness threshold of 1. The area showing hatching in the figure is the pixel area of the output signal “1”.

The higher the luminance threshold, the smaller the region of the output signal "1", that is, the region exceeding the luminance threshold. Further, the region of the output signal "1" in the sub-image having a low luminance threshold includes the region of the output signal "1" of the sub-image having a higher luminance threshold.

Let the image data of the nth sub-image SIm [n] be S [n]. Since the sub-image is a binary image, the image data S [n] is two-dimensional data in which signals "1" or "0" are assigned to each pixel 130. Then, consider the case where the brightness threshold Bth [n] is higher as n is smaller.

FIG. 11 is a logical table showing processing for forming a gradation image. The gradation image GS [n] is composed of the image data S [n] and S [n-1] of the sub-images having the adjacent luminance thresholds. The gradation brightness corresponding to the brightness threshold value Bth [n] is given to the pixel 130 in which “1” is set in the column of GS [n]. As shown in FIG. 11, the gradation Bth [n] is given to the pixel 130 in which S [n] is “1” and S [n-1] is “0”. Gradation image GS [n] can be generated by such signal processing.

The logical formula of the signal processing of FIG. 11 is given by the following formula.

The signal processing of FIG. 11 can be implemented by the circuit of FIG. Whether or not the pixel 130 has the nth gradation GS [n] by the logical product (AND) of the signal obtained by logically inverting the sub-image data S [n-1] by the inverter and S [n]. The result is obtained.

When this signal processing is performed for n = 1 to 4, any of luminance gradation 0 and GS [1] to GS [4] is assigned to each pixel 130, and a gradation image can be generated. As described above, there is an advantage that a gradation image can be generated by a simple processing circuit by signal processing between binary sub-images. Of course, the signal processing of the logical table of FIG. 11 may be mathematically processed using a computer or a CPU (central processing unit).

13 and 14 will be used to describe another embodiment in which a gradation image is generated from a plurality of sub-images having different threshold values.

FIG. 13 is a schematic diagram showing a state in which the image data S [n] of the sub image SIm [n] is stored in the memory. In the figure (k, m), it corresponds to the pixel 130 at the position of k rows and m columns. As shown in FIG. 13, a plurality of sub-images S [n] are arranged on the memory so that the pixels 130 correspond to each other, and the gradation of each pixel 130 is calculated by signal processing of each pixel 130.

As a method of calculating the gradation image, the truth table shown in FIG. 14 is used. A gradation level output GS is obtained according to the values of S [1] to S [4]. In the truth table of FIG. 14, "X" indicates that it may be either "1" or "0". Further, Bth [n] in the output GS column means the brightness threshold value of the sub-image S [n].

The process based on the truth table of FIG. 14 can be easily implemented by using FPGA (Field Programmable Gate Array). Alternatively, it may be implemented by arithmetic processing by the CPU.

The gradation image for each color generated as described above is sent to the image processing unit 20 provided in the image processing unit. The image processing unit 20 receives three image signals of a red (R) image, a green (G) image, and a blue (B) image, synthesizes them at an appropriate ratio, and outputs a color image.

The gradation image generated as described above is displayed on the display device 21 connected to the image processing unit 20. Further, the gradation image is stored in the image recording unit 22 connected to the image processing unit 20 as needed. Of course, the image recording unit 22 may be incorporated into the image processing unit 20.

(Advantage of separating the image processing unit 20)
In this embodiment, as shown in FIG. 1, the image processing unit 20 and the sensor unit 10 are separated and both are connected by a cable 30. Such a separated configuration has the effect of improving radiation resistance.

The sensor unit 10 is installed in a high-dose environment of radiation, and the image processing unit 20 is installed in a low-dose environment. In FIG. 1, the region on the left side (region A) separated by the wall 40 is a high-dose environment, and the region on the right side of the wall 40 (region B) is a low-dose environment. In this way, the image processing unit 20 can be composed of a normal CPU or circuit components having low radiation resistance, which is more preferable.

As a method of further improving the radiation resistance of the imaging system 1 of this embodiment, as shown in FIG. 1, the image processing unit 20 may be surrounded by a radiation shielding material 25 such as a lead plate. Unlike the sensor unit 10, the image processing unit 20 does not impair its function even if it is surrounded by a member that does not allow light to pass through. When the image processing unit 20 and the sensor unit 10 are separately configured in this way, there is an effect that the radiation resistance is further enhanced.

<Example 2>
The imaging system 1 of the second embodiment of the present invention will be described with reference to FIGS. 15 and 16.

In the imaging system 1 of this embodiment, in order to acquire sub-images having different luminance thresholds, a sensor element 13 in which sub-pixels 1300 having different light receiving areas are provided in the pixels 130 is used. In the second embodiment, the description of the configuration having the same function as that of the first embodiment described above will be omitted, and different configurations will be mainly described.

FIG. 15 is a diagram showing the configuration of the sensor element 13 of the imaging system 1 of this embodiment, and shows four pixels 130 in the sensor element 13. In the figure, the portion surrounded by the alternate long and short dash line constitutes one pixel 130. One pixel 130 is composed of four sub-pixels 1300, and the areas of the four sub-pixels 1300 are different from each other.

The configuration of each sub-pixel 1300 is the same as in FIG. However, the light receiving area of the light receiving element 131 of the sub pixel 1300 differs depending on the sub pixel 1300. As shown in the equation (1), when trying to obtain a predetermined voltage reduction amount ΔV, the smaller the light receiving area, the larger the photocurrent density J is required to obtain the predetermined ΔV. Since the light current density J corresponds to the brightness of the observation target, the smaller the light receiving area, the larger the brightness threshold Bth. The numbers shown in each pixel 130 of FIG. 15 are relative values of the brightness threshold Bth of each sub-pixel 1300. The brightness threshold value changes according to the light receiving area of the light receiving element 131.

Further, as can be seen from FIG. 15, since one pixel 130 requires two charging scanning lines 135 and two readout scanning lines 136, the number of scanning lines is twice that of the first embodiment. In this embodiment, it is preferable that the holding capacity 132 is provided separately from the light receiving element 131. The reason is that the size of the junction capacitance of the light receiving element 131 may be substantially proportional to the area of the light receiving element 131. As can be seen from the mathematical formula (1), when the magnitude C of the capacitance is proportional to the area S, the luminance threshold value does not change.

As shown in FIG. 1, a method of acquiring a color image by providing a color separation element 14 that decomposes visible light into RGB is provided in front of the sensor element 13 is the same as that of the first embodiment.

FIG. 16 is a timing diagram schematically showing a reading sequence from the pixel 130 in the sensor element 13 of this embodiment. Since the luminance threshold is changed by the area of the sub-pixel 1300, four sub-images having different luminance thresholds can be obtained only by scanning once in one field period. When the number of pixels is the same, the number of scanning lines is doubled as compared with the first embodiment, but the number of scannings can be reduced because four scannings for each subfield are performed once.

The method of generating the gradation image from the sub image is the same as that of the first embodiment.

(Sub-pixel arrangement pattern)
Further, in the configuration of the pixel 130 of FIG. 15, by setting the extraction direction of the data line 137 to the opposite side between the sub pixels 1300, the distance between the light receiving elements 131 of the sub pixels 1300 is shortened. As an example, the data line 137 of the sub-pixel 1300 having the threshold value 8 extends to the left side, and the data line 137 of the sub-pixel 1300 having the threshold value 2 extends to the right side. By adopting such an arrangement pattern, the light receiving elements 131 between the sub-pixels 1300 are close to each other.

In this way, by adopting the arrangement of the sub-pixels 1300 in which the extraction direction of the data line 137 is opposite between the sub-pixels 1300, the gradation is disturbed even when the brightness change of the observation target is spatially fine. It is less likely to occur, and the effect of reducing the so-called moire phenomenon can be obtained.

<Example 3>
The imaging system 1 of the third embodiment of the present invention will be described with reference to FIGS. 17 and 18.

In the imaging system 1 of this embodiment, the charging voltage Vb0 of the light receiving element 131 is changed in order to acquire sub-images having different luminance thresholds. In the third embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

FIG. 17 is a schematic diagram showing the relationship between the brightness, that is, the amount of light incident on the light receiving element 131 and the terminal voltage.

This figure shows the characteristics when the charging voltage Vb0 is changed to four values of Vb01 to Vb04.

As can be seen from the mathematical formula (1), since ΔV = 0 when the brightness is zero, the terminal voltage V1 of the holding capacity 132 is substantially equal to the charging voltage Vb0. Then, when light is incident and a photocurrent flows, the voltage is reduced by ΔV according to the mathematical formula (1), so that the characteristics shown in FIG. 17 are obtained.

As can be seen from FIG. 17, when the charging voltage Vb0 is changed to four values of Vb01 to Vb04, the brightness at which the terminal voltage V1 of the holding capacity 132 becomes equal to the predetermined threshold value Vth changes. That is, the luminance threshold Bth changes. In this embodiment, this characteristic is used to acquire a plurality of sub-images having different luminance thresholds.

The configuration of the sensor element 13 used in this embodiment is the same as that shown in FIG.

FIG. 18 is a schematic diagram showing the relationship between the read sequence from each pixel 130 and the charging voltage Vb0 in this embodiment.

One field is divided into four subfields SF [1] to SF [4]. In each subfield, the charge scan pulse is sequentially scanned (the timing of the dotted line in the figure), and the read scan pulse is sequentially scanned after the exposure time Δtex has elapsed. The feature of this embodiment is that the charging voltage Vb0 is changed for each subfield. As a result, sub-images having different brightness thresholds can be acquired.

The method of generating the gradation image from the sub image is the same as that of the first embodiment.

<Example 4>
The imaging system 1 of the fourth embodiment of the present invention will be described. This embodiment is a hybrid type that uses a plurality of methods for changing the luminance threshold value described in the mathematical formula (1). This has the effect of being able to acquire an image having a higher number of gradations. In the fourth embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

In this embodiment, the configuration of the sensor element 13 shown in FIG. 15 is used, and the charging voltage for each subfield is changed in the scanning sequence shown in FIG. As an example, when the sensor element 13 composed of four sub-pixels 1300 is used as shown in FIG. 15, an image having four gradations can be obtained. Then, as shown in FIG. 18, when the charging voltage Vb0 is changed in four stages and the sub image is acquired, an image of four gradations can be obtained. As a result, a 4 × 4 16-gradation gradation image can be generated.

<Example 5>
The imaging system 1 of the fifth embodiment of the present invention will be described with reference to FIG. This embodiment is a hybrid type that uses a plurality of methods for changing the luminance threshold value described in the mathematical formula (1). In this embodiment, the change in the exposure time and the change in the charging voltage Vb0 are combined. In the fifth embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

As shown in FIG. 19, the first field includes four subfields SF [1] to SF [4] with different exposure times. Then, in the second field, after changing the charging voltage Vb0, images are acquired in the four subfields in which the exposure time is changed. In this way, eight sub-images having different brightness thresholds are acquired. From this sub-image, an 8-gradation gradation image can be generated by the above method.

Although the description is omitted, as the third aspect of the hybrid type, the sub-pixel 1300 having a different pixel area and the change in the exposure time may be combined.

<Example 6>
The imaging system 1 of the sixth embodiment of the present invention will be described. The imaging system 1 of this embodiment can operate in two imaging modes, a normal mode and a high gradation mode. In the sixth embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

When real-time performance is required, the imaging system 1 of this embodiment obtains an image of four gradations by the drive timing of FIG. This is called normal mode. On the other hand, when a higher gradation image is required, the mode shifts to the high gradation mode. In the high gradation mode, the drive timing shown in FIG. 19 is used. That is, one field is divided into subfields having different exposure times, and imaging is performed over an n-field period while changing the charging voltage Vb0 for each field. Although the case of n = 2 is shown in FIG. 19, it may be set to n = 8. When n = 8, the time required for imaging is eight times longer, but a gradation image of 4 × 8 = 32 gradations can be generated.

The case where the gradation image in the normal mode has 4 gradations is shown, but this is just an example, and the normal mode may have 16 gradations, for example.

The point of this embodiment is that the number of sub-images used to generate the gradation image is larger in the high gradation mode than in the normal mode. As a result, in the high gradation mode, a high gradation image can be captured.

<Example 7>
A robot system will be described with reference to FIG. 20 as an example of an imaging system application device according to a seventh embodiment of the present invention.

The applied device of this embodiment is a robot system that can be used even in a harsh environment such as a high-level radiation environment. In the seventh embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

The robot system of this embodiment includes a robot 100 and a robot control device 200. The robot 100 has a robot base 101 to which the tires 102 are attached, an arm 110, and a sensor unit 10. The arm 110 has a joint 111 and can perform operations such as rotation and refraction. Although not shown, a mechanism that allows the arm 110 to be expanded and contracted may be provided. The sensor unit 10 has the sensor structure of any of the above-described embodiments.

The robot control device 200 is a control device capable of operating the robot 100 by remote control. The robot control device 200 has an image processing unit 20 and a robot control unit 210. The sensor unit 10 and the image processing unit 20 are connected by a cable 30 and transmit and receive signals to and from each other. The robot 100 and the robot control unit 210 are connected by a cable 31, and power is supplied to drive the robot 100 and control signals are transmitted and received. The image processing unit 20 and the robot control unit 210 transmit and receive signals as needed.

In this embodiment, since the sensor unit 10 has excellent radiation resistance, the robot 100 can take an image even in a high level radiation environment. In particular, in this embodiment, the robot 100 (sensor unit 10) is arranged in the region A (left side of the wall 40 in FIG. 20) which is a high-level radiation environment, and the robot 100 (sensor unit 10) is arranged in the region B (right side of the wall 40) which is a low radiation environment. The image processing unit 20 is arranged. As a result, the image processing unit 20 can be operated in a low radiation environment.

Further, as compared with the case of using a vacuum tube type image pickup device such as an image pickup tube, the sensor element 13 constituting the sensor unit 10 of this embodiment is smaller and lighter. Therefore, the robot 100 can be installed in a narrow space, and even if a plurality of sensor units 10 are installed in the robot 100, the increase in weight can be suppressed and the influence on the installation location can be reduced. As a result, the object 300 can be grasped more accurately, and the robot 100 can perform advanced movements.

Further, in the robot system of the present embodiment, it is preferable to adopt a configuration capable of switching between the high gradation mode and the normal mode described in the sixth embodiment, if necessary. When the robot 100 is moving or when the object 300 is operated by the arm 110, the sensor unit 10 is operated in the normal mode. As a result, the image of the object 300 can be acquired at high speed, so that high-speed feedback can be given to the robot control unit 210. On the other hand, when the object 300 or the surrounding image is photographed for recording, the sensor unit 10 is operated in the high gradation mode. As a result, it is possible to record a high-quality image with a high number of gradations.

<Example 8>
The imaging system 1 of the eighth embodiment of the present invention will be described with reference to FIGS. 21 and 22.

In this embodiment, the threshold value determination circuit 134 is not provided in the pixel 130, but is provided for each data line 137. In the eighth embodiment, the description of the configuration having the same function as that of the above-described embodiment will be omitted, and different configurations will be mainly described.

FIG. 21 is a schematic view showing the configuration of the pixel 130 of the sensor element 13 of this embodiment.

The terminal of the holding capacitance 132 is connected to the data line 137 via the readout transistor 143.

FIG. 22 is a schematic view showing the configuration of the sensor element 13 of the imaging system 1 of this embodiment, and shows four pixels 130 in the sensor element 13, but in reality, a larger number of pixels are arranged. ..

Each data line 137 is connected to the input terminal IN of the threshold value determination circuit 134. The output terminal O of the threshold value determination circuit 134 is connected to the transmission / reception unit 12 via the changeover switch 141.

The signal reading procedure in this embodiment will be described. In this embodiment, the scanning pulse is applied at the timing shown in FIG. When the charging scanning pulse is applied to the charging scanning line 135, the charging scanning pulse is applied to the CA terminal of the pixel (FIG. 21) on the selected scanning line, and the charging transistor 133 is turned on. As a result, the light receiving element 131 is charged to the charging voltage Vb0. After that, the charging transistor 133 is turned off.

When a read scan pulse is applied to the read scan line 136 after a predetermined exposure time, the read transistor 143 of the selected pixel is turned on. At this time, the read transistor 143 of the pixel on the unselected scanning line is in the OFF state. Therefore, the voltage of the pixel holding capacity 132 on the selected scan line is output to the data line 137.

At this point, the read pulse generation unit 144 shown in FIG. 22 outputs the read pulse and inputs it to the RE terminal of the threshold value determination circuit 134. As a result, the output terminal O of the threshold value determination circuit 134 is latched to the signal "1" or "0" based on the magnitude relationship between the voltage of the data line 137 and the predetermined threshold value at the time of applying the read pulse.

During this period, the changeover switch 141 is operated by the horizontal scanning pulses sequentially output from the horizontal scanning circuit 140, and the signal voltage (“1” or “0”) of each data line 137 is transferred to the transmission / reception unit 12. Since a binary signal flows through each data line 137 after the output of the threshold value determination circuit 134, the changeover switch 141 may be a logic circuit.

In this way, binary sub-image data can be obtained based on the holding capacity 132 voltage of each pixel. As shown in FIG. 9, by changing the exposure time for each subfield, subimages having different luminance thresholds can be acquired. The method of generating a gradation image from a plurality of sub-images is as described above in the first embodiment.

In FIG. 21, a MOS type FET is used for the readout transistor 143, but in this operation, the FET is operated in the saturation region. Therefore, even if the gate voltage threshold value of the FET changes slightly, the signal is output to the data line 137. The influence of is small. Therefore, the radiation resistance is improved as compared with the case of using a CMOS type amplification amplifier.

According to this embodiment, the circuit in the pixel 130 can be simplified.

Further, in this embodiment, the brightness threshold value is changed by changing the exposure time, but the charging voltage is changed (FIG. 18), the area of the light receiving element 131 is changed (FIG. 15), or a hybrid type in which a plurality of methods are combined. A configuration in which the threshold value determination circuit 134 is provided for each data line 137 can also be applied to (FIG. 19 and the like).

As described above, the image pickup system 1 of the embodiment of the present invention includes a sensor unit 10 and an image processing unit 20, and the sensor unit 10 includes a color separation element 14 for extracting light of a specific wavelength and color separation. It has an image sensor 15 that captures light transmitted through the element 14, the image sensor 15 has a transmission / reception unit 12 and a sensor element 13, and the sensor element 13 has a light receiving element 131 and a charging transistor 133 for each pixel 130. The sensor element 13 has one or a plurality of threshold determination circuits 134 for determining whether the terminal voltage of the light receiving element 131 is equal to or higher than a predetermined threshold value, and the sensor element 13 has a plurality of sensor elements 13 corresponding to different brightness thresholds. Since the sub-image is acquired and the image processing unit 20 processes the signals of the plurality of sub-images to generate a gradation image, it has excellent environmental resistance and is in a harsh environment such as a high-level radiation environment. However, it is possible to provide an image pickup device that can be used, is small and lightweight, and captures an image with at least one color.

Further, in the first embodiment, the color separation element 14 decomposes the incident light into three colors of light, and the sensor unit 10 captures a plurality of images of the light transmitted through the color separation element 14. Having a sensor 15, the imaging system 1 synthesizes images output from each imaging sensor 15 to generate a color image, so that it has excellent environmental resistance and is in a harsh environment such as in a high-level radiation environment. It is possible to provide an imaging device that can be used underneath, is small and lightweight, and captures a color image.

Further, in the first embodiment, since the color separation element 14 is made of an inorganic material, it is possible to suppress the occurrence of browning (browning) due to irradiation with radiation or ultraviolet rays.

Further, in the first embodiment, since the color separation element 14 is a dielectric optical element, it has high hardness and is chemically stable, so that oxidation and alteration are unlikely to occur, and it can be used for a long period of time.

Further, in the first embodiment, since the color separation element 14 causes the transmitted light to travel in a direction different from that of the radiation, the radiation does not directly enter the image sensor 15, and the radiation resistance of the image pickup system 1 can be improved.

Further, in the first embodiment, since the sensor element 13 has the threshold value determination circuit 134 for each pixel 130, it can operate reliably even if the number of scanning lines is large, and the level change due to long transmission of the analog signal. The effect can be suppressed.

Further, since the sensor element 13 changes the luminance threshold value by changing the exposure time of the light receiving element 131 for each sub-image, it is not necessary to provide sub-pixels in the pixels, and the pixel configuration can be simplified.

Further, in the second embodiment, since each pixel 130 of the sensor element 13 includes a plurality of sub-pixels 1300 having different light-receiving areas of the light-receiving element 131, one image can be acquired in one scan and one pixel is read out. You can lengthen the time.

Further, in the third embodiment, since the sensor element 13 changes the charging voltage applied to the light receiving element 131 at predetermined intervals, it is not necessary to provide sub-pixels in the pixels, and the pixel configuration can be simplified. .. Further, the brightness threshold value of the sub-pixel can be changed by changing the voltage for each period of acquiring the sub-pixel. Further, by changing the voltage for each cycle of acquiring a plurality of sub-pixels, the luminance thresholds of the plurality of sub-pixels can be changed at once.

Further, in another embodiment, since the sensor unit 10 and the image processing unit 20 are spatially separated and connected by wire or wirelessly, an imaging device that can be used even in a harsh environment such as a high-level radiation environment. Can be provided. Further, an inexpensive and high-performance semiconductor element can be used for the image processing unit 20.

Further, in another embodiment, since the image processing unit 20 is surrounded by the radiation shielding material 25, it is possible to provide an imaging device that can be used even in a harsh environment such as a high level radiation environment. Further, an inexpensive and high-performance semiconductor element can be used for the image processing unit 20.

Further, in another embodiment, since the threshold value determination circuit 134 has the bipolar transistor Tr2 to which the output voltage of the light receiving element 131 is input, the radiation resistance performance can be improved.

Further, in another embodiment, the imaging system 1 can operate in the normal mode and the high gradation mode, and the number of sub-images acquired to generate the gradation image in the high gradation mode is the order in the normal mode. Since the number of sub-images to be acquired for generating a toned image is larger than the number of sub-images to be acquired, it is possible to obtain an image in which either real-time property or high image quality is prioritized according to the purpose of image acquisition.

The present invention is not limited to the above-described embodiment, and includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to those having all the described configurations. Further, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Further, the configuration of another embodiment may be added to the configuration of one embodiment. In addition, other configurations may be added / deleted / replaced with respect to a part of the configurations of each embodiment.

Further, each of the above-described configurations, functions, processing units, processing means, etc. may be realized by hardware by designing a part or all of them by, for example, an integrated circuit, and the processor realizes each function. It may be realized by software by interpreting and executing the program to be executed.

Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, DVD, or BD. can.

In addition, the control lines and information lines indicate those that are considered necessary for explanation, and do not necessarily indicate all the control lines and information lines that are necessary for implementation. In practice, it can be considered that almost all configurations are interconnected.

1 Imaging system 10 Sensor unit 11 Sensor control unit 12 Transmission / reception unit 13 Sensor element 14 Color separation element 15 Imaging sensor 16R, 16G, 16B Dielectric mirror 17 Half mirror 18 Color filter 19 Reflector 20 Image processing unit 21 Display device 22 Image recording Part 25 Shielding material 30, 31 Cable 100 Robot 101 Robot base 102 Tire 110 Arm 111 Joint 130 Pixel 131 Light receiving element 132 Retaining capacity 133 Charging transistor 134 Threshold determination circuit 135 Charging scan line 136 Read scan line 137 Data line 138 Charging scan circuit 139 Read scan circuit 140 Horizontal scan circuit 143 Read transistor 144 Read pulse generator 200 Robot control device 210 Robot control unit 300 Object 1300 Sub-pixel

Claims (16)

An imaging system including a sensor unit and an image processing unit.
The sensor unit includes a color-separating element that extracts light having a specific wavelength and an imaging sensor that captures light transmitted through the color-separating element.
The image pickup sensor has a sensor element and a transmission / reception unit, and has a sensor element and a transmission / reception unit.
The sensor element is
It has a light receiving element and a charging transistor for each pixel.
It has one or a plurality of threshold value determination circuits for determining whether the terminal voltage of the light receiving element is equal to or higher than a predetermined threshold value.
Acquire multiple sub-images corresponding to different brightness thresholds and
The image processing unit is an imaging system characterized in that it processes signals of the plurality of sub-images to generate a gradation image. The imaging system according to claim 1.
The color separation element decomposes the incident light into three colors of light.
The sensor unit has a plurality of imaging sensors that capture light transmitted through the color separation element.
The imaging system is an imaging system characterized in that an image output from each imaging sensor is combined to generate a color image. The imaging system according to claim 1.
The color separation element is an imaging system characterized in that it is made of an inorganic material. The imaging system according to claim 3.
The color separation element is an imaging system characterized by being a dielectric optical element. The imaging system according to claim 1.
The color separation element is an imaging system characterized in that transmitted light travels in a direction different from that of radiation. The imaging system according to claim 1.
The sensor element is an imaging system characterized by having the threshold value determination circuit for each pixel. The imaging system according to claim 1.
The sensor element is an imaging system characterized in that the brightness threshold value is changed by changing the exposure time of the light receiving element for each sub-image. The imaging system according to claim 1.
An imaging system in which each pixel of the sensor element includes a plurality of sub-pixels having different light-receiving areas of the light-receiving element. The imaging system according to claim 1.
The sensor element is an imaging system characterized in that the charging voltage applied to the light receiving element is changed at predetermined intervals. The imaging system according to claim 1.
An imaging system characterized in that the sensor unit and the image processing unit are spatially separated and connected by wire or wirelessly. The imaging system according to claim 10.
The image processing unit is an imaging system characterized in that it is surrounded by a radiation shielding material. The imaging system according to claim 1.
The threshold value determination circuit is an imaging system characterized by having a bipolar transistor into which an output voltage of the light receiving element is input. The imaging system according to claim 1.
It can operate in normal mode and high gradation mode,
An imaging system characterized in that the number of sub-images acquired to generate the gradation image in the high gradation mode is larger than the number of sub-images acquired to generate the gradation image in the normal mode. .. An imaging system application device comprising the imaging system according to any one of claims 1 to 13. The imaging system application device according to claim 14.
A radiation-resistant device unit having the sensor unit and
An image pickup system application device comprising the control device including the image processing unit and the device control unit for controlling the operation of the image pickup system application device. The imaging system application device according to claim 14.
The robot on which the sensor unit is installed and
An image pickup system application device comprising the image processing unit, a robot control unit that controls the operation of the robot, and a control device having the same.

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