JP2590763B2 - Infrared solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a charge coupled device (CC).
D) An electronic scanning two-dimensional infrared solid-state imaging device according to D).

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional infrared solid-state imaging device. This example employs a progressive scanning configuration. The unit pixel is a light receiving area 12, a transfer gate 5, and a vertical C
It is composed of one stage (four electrodes) of CD13. The unit pixels are two-dimensionally arranged, and each vertical CCD 13
Is connected to the horizontal CCD 15. An output section 16 is provided at the end of the horizontal CCD. All the transfer gates are connected by a common transfer gate wiring 14 so that the same drive signal is supplied. The aperture ratio, which is the ratio of the light receiving area to the pixel area, is the same for all pixels.

[0003]

In the above-described conventional infrared solid-state imaging device, there is a trade-off between the aperture ratio and the maximum transfer charge amount that can be handled by the vertical CCD, and the sensitivity and the dynamic range must be balanced. Was designed.
In other words, both were sacrificed. For this reason, when used in a temperature measurement device or the like, the temperature measurement range is divided by the device, and the temperature range that can be measured by adjusting the aperture or switching the filter is expanded. Therefore, the conventional apparatus has a drawback that a low-temperature subject and a high-temperature subject whose temperature measurement ranges extend over the same screen cannot be captured and the temperature cannot be measured simultaneously.

[0004]

According to the present invention, there is provided an infrared solid-state imaging device according to the present invention, wherein odd-numbered pixels and even-numbered pixels have different aperture ratios, and a vertical charge-coupled device is provided from a light receiving portion. A transfer gate that transfers signal charges to the light-receiving section and defines the bias potential of the light receiving section is separately wired for odd-numbered column pixels and even-numbered column pixels, and has separate terminals, and corresponds to odd-numbered columns and even-numbered columns. However, two sets of horizontal charge-coupled devices and an output section connected to the two sets are provided. A pixel column with a large aperture ratio has a vertical charge-coupled device with a small channel width, and a pixel column with a small aperture ratio has a vertical charge-coupled device with a wide channel width.

[0005]

In the infrared solid-state imaging device according to the present invention, pixels having different aperture ratios are arranged in odd-numbered rows and even-numbered rows, that is, a pixel row having a large light-receiving area and a narrow vertical CCD channel width; Pixel rows having a small area and a wide vertical CCD channel width are alternately arranged. A pixel row having a high aperture ratio has high sensitivity but has a small amount of charge that can be handled. Therefore, the temperature difference detection capability for a low-temperature subject is high, but a high-temperature subject is saturated and the temperature difference cannot be detected. On the other hand, a pixel row having a low aperture ratio has low sensitivity but has a large amount of charge that can be handled, and thus is disadvantageous for detecting a temperature difference for a low-temperature subject, but can detect a temperature difference without being saturated for a high-temperature subject. The bias potential setting conditions in the light receiving sections of these two types of pixel rows are to be determined according to the maximum transfer charge amounts of the corresponding vertical CCDs, and the optimum conditions are different. Since the transfer gates for defining the bias potential are separately wired for the pixels in the odd-numbered columns and the pixels in the even-numbered columns and have different terminals, they can be set independently of each other. Further, since two sets of horizontal CCDs, one corresponding to an odd column and the other corresponding to an even column, are provided and an output unit connected to the horizontal CCD, an image signal composed of odd columns and an image signal composed of even columns are provided. Can be completely separated and taken out. Therefore, according to the present invention, an image signal effective for low-temperature subject temperature measurement and an image signal effective for high-temperature subject temperature measurement can be obtained at the same time. The temperature can be captured and measured at the same time, and the above-mentioned problem is solved.

[0006]

FIG. 1 is a plan view showing the structure of an embodiment of the infrared solid-state imaging device according to the present invention. Light-receiving region 1 with high aperture ratio, transfer gate 5 and vertical C with narrow channel width
A pixel row in which pixels of one stage (four electrodes) of CD3 are arranged in the vertical direction, a light receiving region 2 having a low aperture ratio, a transfer gate 5, and one stage (four electrodes) of a vertical CCD 4 having a wide channel width. An imaging region is configured by alternately arranging pixel rows in which pixels are arranged in a vertical direction. In this example, counting from the output side, odd columns are pixels with a low aperture ratio, and even columns are pixels with a high aperture ratio. The transfer gate 5 for defining the bias potential of the light receiving region is connected to separate wirings 6 and 7 for odd and even columns, and the transfer gate wiring 6 for odd columns has a φTG _odd terminal, The transfer gate wiring 7 has a φTG _even terminal.

A horizontal CCD is provided below the image pickup area. The horizontal CCD is composed of two odd-numbered columns 8 and even-numbered columns 9. All the vertical CCDs are connected to odd-numbered horizontal CCDs 8. A transfer mechanism is provided between the odd-row horizontal CCD 8 and the even-row horizontal CCD 9 for transferring the signal charges from the even-row vertical CCD from the odd-row horizontal CCD 8 to the even-row horizontal CCD 9. Even column vertical CCD
Since the maximum transfer charge amount is smaller than that of the odd column vertical CCD, if the odd column horizontal CCD 8 is provided immediately below the imaging area as shown in the figure, the maximum transfer charge amount can be reduced by reducing the channel width of the even column horizontal CCD 9. Is smaller than that of the odd-numbered horizontal CCD 8. Two horizontal CCD8
9 and 9 are connected to an odd-numbered column output unit 10 and an even-numbered column output unit 11, respectively. Each of the two output units 10 and 11 has a charge-voltage conversion coefficient suitable for the amount of charge to be handled. For example, a vertical CCD 3 with a narrow channel width
(Even line) and vertical CCD 4 with wide channel width (odd line)
Assuming that the maximum transfer charge ratio is 1: 2, if the charge-to-voltage conversion coefficient ratio of the even-numbered column output unit 11 and the odd-numbered column output unit 10 is set to 2: 1, the signal processing device can use either of them. Almost the same thing can be used for the column, which is convenient.

FIG. 2 shows an accumulation state of signal charges in pixels when a low-temperature subject and a high-temperature subject are imaged.
Here, (a) is a case where a low-temperature subject is imaged,
(B) is a case where a high-temperature subject is imaged. The horizontal axis represents the elapsed time since the light receiving unit was reset by the read operation of the transfer gate, and the vertical axis represents the accumulated charge amount of the light receiving unit. It is most effective to set the reset potential of the transfer gate so that the maximum accumulated charge in the light receiving section of each pixel matches the maximum transfer charge of the corresponding vertical CCD. Such a setting is possible because the transfer gates are separately provided for odd columns and even columns. The “accumulation time” in the figure is the time until the next reset is performed, and the accumulated charge amount becomes zero in the actual operation. As shown in (a),
When a low-temperature subject is imaged, the rate of increase of signal charges is slow, but a large amount of signal charges is generated within the accumulation time with a high aperture ratio, and good temperature measurement can be performed. As shown in (b), when a high-temperature subject is imaged, the rate of increase of the signal charge is fast, and a pixel having a high aperture ratio is saturated and cannot be measured, but a pixel having a low aperture ratio has a low aperture ratio. Since the rate of increase of the signal charge is slower and the maximum charge amount is larger than that of the pixel having a higher value, the temperature measurement enabled state can be maintained. The infrared solid-state imaging device of the present invention can simultaneously output the two types of image signals obtained as described above by the above-described configuration. Therefore, if a temperature measurement device or the like is used to configure the same, a low-temperature subject and a high-temperature subject can be identified. It becomes possible to measure the temperature simultaneously by capturing it in the pixel.

[0009]

As described above, in the infrared imaging device according to the present invention, the odd-numbered pixels and the even-numbered pixels have different aperture ratios, and the odd-numbered pixels and the even-numbered pixels have different transfer gates. Since it is configured to have two sets of horizontal charge-coupled devices, one corresponding to an odd-numbered row and the other corresponding to an even-numbered row, and another output terminal connected thereto, a high sensitivity advantageous for low-temperature subject temperature measurement is provided. It is possible to simultaneously output both an image signal and a high dynamic range image signal that is advantageous for a high-temperature subject. Therefore, the use of the infrared solid-state imaging device of the present invention has an effect that a low-temperature subject and a high-temperature subject can be captured on the same screen, and a temperature measuring device or the like capable of simultaneous temperature measurement can be configured.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of an embodiment of an infrared solid-state imaging device according to the present invention.

FIGS. 2A and 2B are diagrams illustrating the accumulation state of signal charges in a pixel having a high aperture ratio and a pixel having a low aperture ratio, wherein FIG. 2A illustrates a case where a low-temperature subject is imaged, and FIG. I have.

FIG. 3 is a plan view showing a configuration of a conventional infrared solid-state imaging device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light-receiving region with high aperture ratio 2 light-receiving region with low aperture ratio 3 vertical CCD with narrow channel width 4 vertical CCD with wide channel width 5 transfer gate 6 transfer gate wiring (for odd columns) 7 transfer gate wiring (for even columns) 8 Horizontal CCD (for odd columns) 9 Horizontal CCD (for even columns) 10 Output unit (for odd columns) 11 Output unit (for even columns) 12 Light receiving area 13 Vertical CCD 14 Transfer gate wiring 15 Horizontal CCD 16 Output unit

Claims (2)

(57) [Claims] 1. An infrared solid-state imaging device in which light receiving units are two-dimensionally arranged and electronically scanned by charge-coupled devices provided in a vertical direction and a horizontal direction, wherein an odd-numbered pixel and an even-numbered pixel have different aperture ratios. A transfer gate for transferring signal charges from the light receiving section to the vertical charge coupled device, and defining a bias potential of the light receiving section, is separately wired for odd-numbered column pixels and even-numbered column pixels, and has a separate terminal. An infrared solid-state imaging device comprising two sets of horizontal charge-coupled devices, one corresponding to an odd-numbered column and the other corresponding to an even-numbered column, and an output unit connected thereto. 2. The infrared solid-state imaging device according to claim 1, wherein the pixel column having a large aperture ratio has a vertical charge-coupled device having a small channel width, and the pixel column having a small aperture ratio has a vertical charge-coupled device having a wide channel width. .