JPH03270579A - Infrared ray image pickup device - Google Patents

Abstract

PURPOSE:To realize an infrared ray image pickup device without saturation even in the case of incidence of a strong infrared ray with a wide image pickup temperature range by transferring a charge overflowed from a 1st transfer channel through a 2nd transfer channel and adding the charge transferred through the 1st transfer channel and a part of the overflowed charge transferred through the 2nd transfer channel. CONSTITUTION:A charge in excess of a level depending on a prescribed voltage OFG when much incident luminous quantity reaches is passed through a overflow gate 17 and stored in a transfer clock phi1 supply stage 19a of a 2nd transfer channel 19 when a transfer gate 18 is conductive. The stored charge of each picture element is transferred multiplexedly through the 1st and 2nd transfer channels 14, 19 respectively by using quadrature transfer clocks approx.=1-phi4 and signals transferred through the 1st and 2nd channels are added with a adder 23 in a form of charges and the result is outputted from a terminal 24 as a picture signal. The relation between the incident luminous quantity and an output voltage from the terminal 24 is nonlinear, saturation is prevented even when a strong infrared ray is made incident, the pickup temperature range is widened without losing information from the image pickup object.

Description

[Detailed Description of the Invention] [Summary] Regarding an infrared imaging device that obtains infrared images using an infrared solid-state imaging device, the purpose of this invention is to widen the imaging temperature range without saturating even when strong infrared rays are incident. a photoelectric conversion unit that receives light and photoelectrically converts it; a first transfer channel that accumulates the charges generated in the photoelectric conversion unit, multiplexes the charges, and transfers the charges;
a second transfer channel that accumulates charges overflowing during accumulation in the first transfer channel and then multiplexes and transfers the charges;
A part of the charge overflowing from the transfer channel is divided and transferred to the second transfer channel.
a charge dividing section that divides and detects a part of the charge accumulated in the first transfer channel or transferred through the second transfer channel; and an addition section that adds the charges transferred and extracted through the second transfer channel and outputs the result as an image signal.

[Industrial application field]

The present invention relates to an infrared imaging device, and more particularly, to an infrared imaging device that obtains an infrared image using an infrared solid-state imaging device.

In recent years, with the demand for higher performance of infrared sensor technology, high-quality infrared images are required, and IRCCD (infrared solid-state image sensor)
charge coupled device
Although the development of e) is progressing, the temperature range that can be imaged by IRCCD is relatively narrow, and there is a need to expand this.

[Conventional technology]

In a conventional infrared imaging device using an IRCCD, the output voltage of the IRCCD is proportional to the incident infrared light, and the sensitivity is the same when the amount of incident light is small and when it is large.

[Problem to be solved by the invention]

In conventional devices, when strong infrared rays are incident, the amount of charge generated in the photoelectric conversion diode exceeds the amount of charge that can be transferred and processed by the charge-coupled device (CCD), and the output signal of the CCD becomes saturated at a certain level. Information on whether infrared rays with a certain intensity pattern are incident is lost.

Furthermore, this tendency is reflected at wavelengths 3, where the absorption of infrared rays by the atmosphere is small.
There was a problem in that strong abrasion occurred at ~5 μm, narrowing the imaging temperature range.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an infrared imaging device that does not become saturated even when strong infrared rays are incident, and has a wide imaging temperature range.

[Means to solve the problem]

The infrared imaging device of the present invention includes: a photoelectric conversion section that receives infrared rays and converts them photoelectrically; a first transfer channel that accumulates charges generated in the photoelectric conversion section, multiplexes the charges, and transfers them; and a first transfer channel that After accumulating the charge overflowing during accumulation, a second transfer channel multiplexes and transfers the charge; and a part of the charge overflowing from the first transfer channel is divided and accumulated in the second transfer channel, or a charge dividing section that divides and detects a part of the charge transferred through the second transfer channel; and an addition section that adds the charges transferred and extracted from the first and second transfer channels and outputs the result as an image signal. and has.

[Effect]

In the present invention, the charge overflowing from the first transfer channel is transferred to the second transfer channel, and the charge transferred through the first transfer channel and the overflow charge transferred through the second transfer channel are combined. Since the amount of light is added, the sensitivity is high when there is a small amount of incident photoelectricity that does not cause charges to overflow from the first transfer channel, and the sensitivity is low when there is a large amount of incident light that causes charges to overflow from the first transfer channel. This prevents the output signal from becoming saturated even when strong infrared rays are incident, making it possible to widen the imaging temperature range.

〔Example〕

FIG. 1 shows a structural diagram of a first embodiment of the device of the present invention.

In the figure, charges generated by photoelectric conversion of incident infrared rays in the photoelectric conversion diode IO pass through an input gate (11) to which a constant DC bias (IG) is applied, and then through a transfer gate 12 in the accumulation mode, and are transferred to the first transfer. It is stored in the transfer lock φ1 supply stage 14a of the channel 14. The transfer gate is conductive during the high level (hereinafter referred to as H level) period of the transfer lock φT shown in FIG. 2(A), that is, during the accumulation mode.
It is cut off during the low level (hereinafter referred to as L level) period, that is, during the read mode. Further, the discharge goo H5 is supplied with the anti-transition feed lock φT of FIG. 2(B), conducts only in the read mode, and discharges and absorbs the charge from the input gate 12 into the DC current 16. Note that the transfer lock φ1 is kept at a constant H level in the accumulation mode as shown in FIG. 2(C).

When the amount of incident light is large, the charge exceeding the level determined by the constant voltage OFG passes through the overflow gate 17, and is further transferred to the second transfer when the transfer gate 18 conducts when the transfer lock φ9 is at the H level as shown in FIG. 2(G). It is stored in the transfer lock φ1 supply stage 19a of the channel 19. In addition, the discharge gate 20 becomes conductive when the transfer lock φ, -1 shown in FIG. ) is discharged and absorbed by 21.

The 11th and 2nd transfer channels 14 and 19 are shown in Figure 2 (C).
The accumulated charges of each pixel are multiplexed and transferred by the four-phase transfer locks φ1 to φ4 shown in ~(F), and the signals transferred through the first and second channels are added in the form of charges in the adder 23. and outputs it as an image signal from the terminal 24.

Here, the ratio of the H level period of transfer lock φ and the H level period of transfer lock φN- in the accumulation mode is set to 1.
:N-1, the charge transferred to the second transfer channel will be divided by 1/H. For this reason, the relationship between the amount of incident light and the output voltage from the terminal 24 becomes non-linear as shown in Figure 3, and saturation is prevented even when strong infrared rays are incident, and information from the object to be imaged is not lost. The imaging temperature range becomes wider.

FIG. 4 shows a structural diagram of a second embodiment of the device of the present invention.

In the figure, the charge generated in the photoelectric conversion diode 30 is passed through the input gate 31 to which a constant DC bias (IG) is applied, and is transferred to the transfer gate which is conductive when the transfer lock is at H level as shown in FIG. 5(A). The transfer lock φ of the first transfer channel 33 is accumulated in the supply stage 33a (FIG. 5(B)) through the transfer lock φ.

When the amount of incident light is large, the charge exceeding the level determined by the constant voltage 0FG1 passes through the overflow gate 34 to the second
It is stored in the transfer lock-N1 supply stage 35a of the transfer channel 35. Furthermore, constant voltage 0FG1 (OFCI<○F
Charges exceeding the level determined by G2) are discharged from the terminal 37 of the voltage OFD through the overflow gate 36.

The first and second transfer channels 33 and 35 are shown in FIG. 5(B).
The four-phase clock φ9 shown in ~(D). ~φN4 multiplexes and transfers the accumulated charges of each image. The detection stage of the transfer channel 33 has a gate electrode 33 having the same width as the channel width.
The detection stage of the transfer channel 35 is provided with two gate electrodes 35b and 35c that divide the channel width, and each of these gate electrodes 33b, 35b, and 35c has a transfer lock in order to transfer charges. H level and L
It is assumed that there is a constant level V between the level and the level V. The gate electrodes 33b and 33b are commonly connected and connected to an inverting input terminal of an operational amplifier 40 constituting a floating gate amplifier. The charges in each transfer channel detected by the gate electrodes 33b and 35b are generated when the capacitor 41 of the floating gate amplifier is at the H level of the reset clock φR (synchronized with the clock φ) as shown in FIG. 5(E). After being discharged, it is integrated and output from the terminal 42 as an image signal.

Here, if the ratio of the area of the gate electrode 33b to the area of the gate electrode 35b is N:1, the sensitivity until the first transfer channel is saturated and the sensitivity after the saturation are N:1. The relationship with the output voltage is non-linear as shown in FIG. 3, preventing saturation even when strong infrared rays are incident, and widening the imaging temperature range without losing information from the object to be imaged.

〔Effect of the invention〕

As described above, according to the infrared imaging device of the present invention, the relationship between the output signal of the device and the incident infrared rays is non-linear, and the output signal does not become saturated even when strong infrared rays are incident, and the imaging temperature range is widened, making it suitable for practical use. Above all, it is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of the first embodiment of the device of the present invention, FIG. 2 is a signal time chart of the device of FIG. 1, FIG. 3 is a characteristic diagram of the device of the present invention, and FIG. A structural diagram of the second embodiment, and FIG. 5 is a signal time chart of the device of FIG. 4. In the figure, 10.30 is a photoelectric conversion diode, 12.18.32 is a transfer gate, 14.19, 33.35 is a transfer channel, 16.21 is an exhaust gate, 17.34.36 is an overflow gate, 33b, 3
5b and 35c indicate gate electrodes. Fig. 1 Signal time chart of the device Fig. 2 Incident light amount Incident light amount vs. output voltage characteristics Fig. Structure diagram of the second embodiment of the device of the present invention

Claims (1)

[Claims] A photoelectric conversion unit (10, 3) that receives infrared light and converts it into electricity.
0) and a first transfer channel (10, 30) that accumulates the charges generated in the photoelectric conversion unit (10, 30), multiplexes them, and transfers them.
14, 33) and the first transfer channel (14, 33)
After accumulating the charge overflowing during accumulation, the second transfer channel (19, 35) multiplexes and transfers the charge, and a part of the charge overflowing from the first transfer channel (14) is divided and transferred to the second transfer channel (19, 35). a charge dividing unit (35b, 35c) that divides and detects a part of the charge accumulated in the transfer channel (19) or transferred through the second transfer channel (35);
Adding units (23, 40, 4
1) An infrared imaging device comprising: