JPH03187583A - Infrared image pickup device - Google Patents

Abstract

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

Description

[Detailed description of the invention] [Summary] Infrared device f using a solid-state image sensor having a self-scanning function
ll'! Regarding AM, in order to keep the element temperature of a solid-state image sensor constant, signal charges obtained by photoelectric conversion by multiple infrared light receiving elements arranged in one direction are input to a charge transfer element. An optical scanning means performs optical scanning in a direction orthogonal to the one direction to incident light from the object to be imaged on the solid-state imaging device that applies a drive pulse for charge transfer at a first repetition frequency to accumulate and transfer the charge. In full external imaging Si@,
temperature detection means for detecting the element temperature of the solid-state image sensor; pulse generation means for generating pulses with a second repetition frequency approximately inversely proportional to the element temperature based on the temperature detection signal from the temperature detection means; selectively outputting a drive pulse for charge transfer having the first repetition frequency to the solid-state image sensor T during an effective scanning period of the optical scanning period of the optical scanning means;
During the blunting period of the remaining optical scanning period, the apparatus is configured to include a selection means for selectively outputting the pulse of the second repetition frequency from the pulse generation means to the solid-state image sensor as a drive pulse for charge transfer.

[Industrial application field]

The present invention relates to an infrared imaging device δ, and more particularly to an infrared imaging device using a solid-state imaging device having a self-scanning function.

A solid-state m-image element is a solid-state m-image element that photoelectrically converts infrared light from an imaged object using a plurality of infrared receiving elements arranged in one direction, injects the obtained charge into a charge-coupled device (COD), and then transfers and reads it out. , -dimensional IRCCD (Infrared
Charge Coupled Device). The infrared 89 imaging device using this -dimensional IRCCD is being widely applied in the industrial field because it can accurately grasp the temperature distribution of the object to be imaged.

Solid-state W& with self-scanning function such as IRCCD mentioned above
In an infrared imaging device using an image element, it is necessary to maintain the element temperature of the solid-state image sensor constant regardless of the ambient temperature in order to improve performance.

[Conventional technology]

FIG. 5 shows a configuration diagram of an example of a main part of a conventional infrared imaging VT device. In the figure, 51 is a detector container, inside which is a photodiode array (PV array) 52.0CD53. The final stage source follower MO8 type field effect transistor (
A one-dimensional IRCOD consisting of 54 FETs is built-in. The PV array 52u has a configuration in which a plurality of photodiodes, which are infrared sensing elements T, are arranged in one direction, and the output end of each photodiode is connected to the CCD 53.

Further, the source of the FET 54 is grounded via a load resistor 55 provided outside the detector container 51, and is connected to the input @i'F of the amplifier 56. Reference numeral 57 denotes a refrigerator, which is provided to cool the IRCOD inside the detection organ 51.

The longitudinal direction of the Pv array (photodiode arrangement direction) is
The light from the scanned object to be imaged is received by the P-array 52. PV/'
The ray 52 photoelectrically converts the incident infrared light and transfers the obtained signal charge to the CCD 53.

The CCD 53 sequentially converts the input signal charges into input drive pulses and transfers them toward the FET 54. At the final stage, the charges are converted into voltage and applied to the gate of the FET 54. As a result, the voltage generated across the load resistor 55 is outputted to a signal processing circuit (not shown) through the amplifier 56.

Here, as shown in FIG. 6, the main power consumption generating parts inside the sensing organ 51 are the transfer section by the CCD 53 and the source follower FET 54.

In the same figure, 4-phase clocks (driving pulses) from φ1 to φ4G
The voltage is applied to the corresponding transfer electrodes 581 to 584 separately. Four transfer electrodes 581 to 584 are provided corresponding to one photodiode. That is, four transfer electrodes are provided corresponding to each photodiode of the PV array 52.

The four-phase clocks φ1 to φ4 are as shown in FIG. 7(C).
If the PV array 52 is composed of M photodiodes arranged one-dimensionally in the vertical direction, the driving pulses have phases different by 90' from each other. charge transfer (that is, transfer of signal charges of all M photodiodes arranged in the vertical direction) is performed.

By setting the drive pulse φ4 to the transfer electrode 584', which is provided corresponding to the final stage photodiode shown in FIG. Signal charge 6 accumulated in
3, as the drive pulse φ4 changes to the second electric field, the potential directly under the transfer electrode 584' is raised as shown by the broken line 64, so the output gate (OG) is at a constant potential 65 lower than this. The voltage is input to the diffusion layer (floating diffusion) 60 through directly below the voltage 59, where it is converted into a voltage and then applied to the gate of the FET 54.

At this time, the FET 61 is turned off.

The FET 61 passes through the diffusion layer 60 directly under the output gate 59.
A pulse φ is applied before LX when the next bit of signal charge is input to
It is turned on by R, and the charge in the diffusion layer 60 is dumped into the semiconductor substrate via the FET 61, and then it is turned off again to prepare for inputting the signal charge of the next bit to the expansion r& layer 60.

Note that FIG. 7(A) shows the characteristics of the scanning angle with respect to time of the above-mentioned optical scanning means, and shows that optical scanning is performed in the horizontal direction with a period To. Also, the same figure (8)
shows the relationship between the frame time of the CCD 53 and the optical scanning period "0", where the periods T+ and T2 before and after the optical scanning period Y0 are blanking periods that do not contribute to imaging, and the remaining linear ra (This is the effective scanning period for imaging, which is N frame time. The effective scanning rate η is expressed as ra/ro. Also, the charge transfer drive pulses φ1 to φ4 shown in FIG. 7(C) is a constant frequency during the period "0".

By the way, inside the detector container 51, as shown in FIG. 6, the CCD 53 consumes power P1 expressed by the following formula % formula % (1), and the FET 54 consumes power P1 expressed by the following formula % formula % [] P2 is consumed. Therefore, power consumption P inside the detector container 51. is Po =P+ +P2 - to -f-C-V! 2+■2・v2 (It becomes 311.

The refrigerator 57 described above has the above-mentioned power consumption P. To cool down the IRCOD element F'lA degree inside the detector container 51 generated by
The refrigerator 57 is required to have high cooling performance.

[Problem to be solved by the invention]

However, the element temperature of IRCCD is the above power consumption Po.
It changes not only when the temperature of the surrounding environment around the detector container 51 changes, so even if the predetermined element temperature is obtained by the refrigerator 57 at the set ambient temperature,
When the ambient environment temperature changes, the cooling capacity of the refrigerator 57 changes accordingly, and the element temperature also changes. There is a problem in that the performance as an external 1i111 image device deteriorates.

The present invention has been made in view of the above points, and an object of the present invention is to provide an infrared imaging device in which the element temperature can be adjusted to a constant level.

[Means to solve the problem]

FIG. 1 shows a basic configuration diagram of the present invention. As shown in FIG. 1, the present invention includes a plurality of infrared receiving elements F arranged in one direction
A solid-state image sensor that inputs the signal charge obtained by photoelectric conversion in -11 to the charge transfer element 12, and accumulates and transfers it by applying a first repetitive charge transfer drive pulse of 6 frequencies? 1
3, the optical scanning means 14 performs optical scanning in a predetermined direction with respect to the above-mentioned one direction, and the infrared light from the m image object is incident [1111 In the imaging device, the temperature detection means 1
The device is equipped with a 5° pulse generating means 16 and a selecting means 17.

Here, the temperature detection means 15 detects the element temperature of the solid-state image sensor 13. Further, the pulse generating means 16G generates pulses having a second repetition frequency that is approximately inversely proportional to the temperature. Further, the selection means 17 selectively outputs a drive pulse for charge transfer having a first repetition frequency to the solid state [1 element 13] during the effective scanning period of the optical scanning period of the optical scanning means 14, and outputs the driving pulse for charge transfer having the first repetition frequency during the blanking period. The pulse with the repetition frequency is selectively outputted as the drive pulse for loading/retracting transfer of 'i4'.

[Effect]

The optical scanning means 14 scans in a predetermined direction at an optical scanning period of 0 as shown in FIG. 2(A). This optical scanning period "0" is the period T2 when the frame time optical scanning ends and the scanner returns to its original state, and the period "1" is the period until the scanning angle changes linearly with time. This results in an irrelevant planting period.

The present invention is applicable to this blanking period r+, when T2 is reached at 14
In this plan, the driving pulse for charge transfer to the solid-state image sensor 13 during the 1st period T+ and T2 is shown in FIG. 2(B).
As shown in (C), the second repetition frequency (transfer frequency) fI from the pulse generation means 16 is set, and this second repetition frequency f2 is changed in approximately inverse proportion to the element temperature detected by the humidity detection means 15. It is something that makes you

As a result, the blanking interval r during the optical scanning period "0"
The power consumption PB of the solid-state image sensor 13 at +rz (=To -ra) is expressed by the following equation from equation 0.

PB=((-“.-Ta)/T0) ・(K-fI ・
C・V+ 2+Iz・Vz) (4
) On the other hand, during the effective scan 11 ``a'', a drive pulse for charge transfer having a constant first repetition frequency (transfer frequency) fI unrelated to the element temperature is taken out from the selection means 17 and applied to the solid-state imaging element 13. Therefore, the power consumption P^ at this time is expressed by the following equation from equation 0.

PA-(Ta/To)・(K-fl・C・■I2+
Iz ・Vz〉 ■Therefore, the power consumption P of the present invention is P=l) ^ + P 8 = (Ta/T)・(K-fI-C-V12+Iz ・
Vz) 4((D0-Ta)/To) ・(K-fI ・C
・V+ 2+−12・Vz) (6), which changes approximately in inverse proportion to the transfer frequency f2.

That is, according to the present invention, the ! ! The power P can be 1111w. In addition, in the present invention, U
Although the transfer frequency changes during blanking, the blanking period is a period unrelated to image display and has no effect on image display.

〔Example〕

FIG. 3 shows a configuration diagram of an embodiment of the present invention. In the figure, the same components as in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. In Fig. 3, the light from the object to be imaged is transmitted through the lens 2.
1 and enters the mirror 22 , where the optical path is changed by total reflection, and then passes through the lens 23 and enters the movable mirror 24 .

The movable mirror 24 constitutes the optical scanning means 14 together with a timing generation circuit 25, a scan driver 26, and a scanner 27, which will be described later. Rotates back and forth within the angular range. As a result, optically scanned light is extracted from the movable mirror 24, passes through the lens 28, and enters the solid-state imaging device l3 (IRCCD).

Solid-state photography 111 elements? 13 is sealed in a container of the detector 29 and frozen by a refrigerator 30. Further, a sensor 31 constituting the temperature detecting means 15 is attached to a predetermined position of the solid-state image sensor 13. This sensor 31 detects the element temperature 1f of the solid-state image sensor 13 and outputs a signal.

The video signal taken out from the final stage source follower FET (corresponding to 54 in FIG. 5) of the solid-state image sensor 13 is input to the A/D converter 33 through the 7-amp 32 (corresponding to the amplifier 56 in FIG. 5). , after being converted into a digital signal, is supplied to the signal processing/display circuit 34.

The signal processing/display circuit 34 performs offset and sensitivity correction on the human-powered digital video signal through digital signal processing, performs scan conversion, and outputs the corrected data to the D/A converter 35 in an order that can be displayed on a TV. D/A converter 35
converts this data again into a 7f log signal and inputs the 7f log signal to a display device 36 using a cathode ray tube (CRT), where an infrared image is displayed.

On the other hand, the timing generation circuit 25 generates various timing pulses for driving the solid-state imaging system f13, driving the scanner 27, and for correction and display. Love? The na driver 26 receives this timing pulse and generates a voltage waveform for driving the scan sensor 27.

The frequency control circuit 37 constitutes the above-mentioned pulse generation means 16, and the temperature detection signal from the diode sensor 31 is manually inputted to generate a pulse (
Generates a 4-phase clock.

The driver bias power supply 38 has the above-mentioned selection means 17 61, and outputs a pulse from the frequency υJti circuit 37, a four-phase clock with a first repetition frequency of "1" from the timing generation circuit 25, and a pulse from the frequency υJti circuit 37. 4-phase charge transfer drive pulses φ1 to φ4 and a bias voltage are supplied to the solid-state image sensor 13.

FIG. 4 shows a block diagram of one embodiment of the frequency control circuit 37 and driver bias voltage 38 described above. In the same figure,
One eye detected from the sensor 31 is converted to 7 by the A10 converter 41.
After being analog-to-digital converted, it is applied to a read-only memory (ROM) 42 as a 7dress signal.

The ROM 42 stores in advance a table indexed by the input address, generates a digital signal having a value substantially inversely proportional to the input address, that is, the detection element temperature, and supplies it to the frequency dividing circuit 43 . The frequency divider circuit 43 is configured to frequency divide the pulse of a constant repetition frequency from the oscillation circuit 44 by a frequency division ratio that is variably controlled according to the value of the digital signal from the frequency divider circuit 43. As a result, a pulse with a repetition frequency f2 approximately inversely proportional to the element temperature is taken out from the frequency dividing circuit 43 and supplied to the waveform generation circuit 45, which generates four-phase driving pulses with the same repetition frequency "2".

The data selector 46 receives data from the timing generation circuit 25.
Based on the seat signal, the optical scanning period "a" is the effective scanning tree interval "a" selects and outputs four-phase driving pulses of the first repetition frequency f1 from the timing generation circuit 25;
During the remaining blanking period (ro-ra), drive pulses from the waveform generation circuit 45 are selectively output.

The drive pulse from the driver 41t data selector 46 is amplified to the required power and is supplied to the solid-state imaging system F13 together with the bias voltage as drive pulses φ1 to φ4 for charge transfer.

According to this embodiment, for example, the surrounding ring i! Even if the temperature of the hot water drops and the cooling capacity of the refrigerator 30 changes to cool the solid-state image sensor 13 to a predetermined temperature or higher, the second repetition frequency f2 becomes low, and the blanking period ('ro-Ta) increases. Since the power consumption PB increases and the solid-state image sensor 13 is controlled to generate more heat, the element temperature is maintained at a substantially constant temperature without decreasing. Even when the ambient temperature rises, the element temperature is maintained at a substantially constant temperature by the operation opposite to the above.

Note that the present invention is not limited to the above-described embodiment, and for example, the circuit portions of the frequency dividing circuit 43 and the oscillation circuit 44 in FIG. It may also be configured with an oscillation circuit.

〔Effect of the invention〕

As described above, according to the present invention, the ambient environment temperature changes,
Even if the cold fJIff changes by 1 degree, the blanking power consumption of the solid-state image sensor will be reduced by 1II depending on the element temperature.
Since the tIl is constant, the elementary Fa degree can be controlled to be almost constant at all times without adversely affecting the displayed infrared image.
Therefore, it has features such as greatly contributing to improving the performance of infrared imaging devices.

[Brief explanation of drawings]

Figure 1 is a diagram showing the principle of the present invention; Figure 2 is a detailed explanatory diagram of the present invention; Figure 3 is a diagram showing the configuration of an embodiment of the present invention; Example block diagram, 5th
The figures are a configuration diagram of an example of a conventional main part, FIG. 6 is an explanatory diagram of a point where dissipated power is generated inside the U detector, and FIG. 7 is an explanatory diagram of optical scanning, frame time, and drive pulses in the conventional device. In the figure, 11 is an infrared light receiving element, 12 is a charge transfer element, 13 is a solid-state imaging system f, 14 is a GJ optical scanning means, 15 is a temperature detection means, 16 is a pulse generation means, 17 is a selection means, 31 is a rainbow sensor, 37 38 indicates a frequency detection circuit, and 38 indicates a driver bias power supply.

Claims (1)

[Claims] Signal charges obtained by photoelectric conversion by a plurality of infrared light-receiving elements (11) arranged in one direction are input to a charge transfer element (12), and a signal charge of a first repetition frequency is An optical scanning means (14) performs optical scanning in a direction orthogonal to the one direction to incident light from the object to be imaged onto the solid-state imaging device (13) that applies a drive pulse for charge transfer to accumulate and transfer the charge. An infrared imaging device comprising: temperature detection means (15) for detecting the element temperature of the solid-state image sensor (13); pulse generating means (16) for generating pulses with a repetition frequency of 2; the optical scanning means (16);
14) During the effective scanning period of the optical scanning period, the charge transfer drive pulse of the first repetition frequency is selectively outputted to the solid-state image sensor (13), and during the blanking period of the remaining optical scanning period, the pulse generation is performed. An infrared imaging device comprising: selecting means (17) for selectively outputting the pulse of the second repetition frequency from the means (16) as a drive pulse for charge transfer to the solid-state imaging device (13). .