JPH0384430A - Infrared detector - Google Patents

Abstract

PURPOSE:To suppress a noise caused by temperature change by providing a variable voltage generation means which recognizes the temperature change detected by a temperature sensor and makes the voltage on both ends of a photoconductive semiconductor detecting element constant and a variable gain control and amplification means. CONSTITUTION:The voltage change caused by the change of the resistance of the photoconductive semiconductor detecting element 1 in a range where the temperature change occurs and the voltage change caused by the change of responsivity are previously obtained. The temperature change of the element 1 is detected by the temperature sensor 3 and informs of it to the variable voltage generation means 4 and the variable gain control and amplification means 5. The means 4 previously sets the voltage which is generated to make the voltage on both ends of the element 1 constant and generates the voltage corresponding to the temperature detected by the sensor 3 so as to suppress the noise caused by the change of resistance. Meanwhile, the means 5 selects a gain variable resistance value corresponding to the temperature detected by the sensor 3 to suppress the noise caused by the change of the responsivity.

Description

[Detailed Description of the Invention] (Summary) A high resistance is connected in series to a photoconductive semiconductor sensing element, and a voltage is applied to both ends by a voltage generating means to cause a constant current to flow. Our objective is to provide an infrared detector that can suppress noise even if there is a temperature change of about 1 degree at the operating temperature, regarding an infrared detector that amplifies the signal generated by inputting infrared rays to the element and outputs the amplified signal. , a temperature sensor that detects a temperature change of the photoconductive semiconductor sensing element without delay is provided, and the voltage generating means recognizes the temperature detected by the temperature sensor, and even if there is a temperature change, the photoconductive type The variable voltage generating means generates a voltage that keeps the voltage across the semiconductor sensing element constant, and the amplifier recognizes the temperature detected by the temperature sensor and keeps the voltage across the photoconductive semiconductor sensing element constant. However, it is preferable to use variable gain control amplification means to cancel out changes in signal voltage caused by temperature changes.

[Industrial application field]

The present invention connects a high resistance in series to a photoconductive semiconductor sensing element which is an image sensor, applies a voltage to both ends by voltage generating means to flow a constant current, and infrared rays are applied to the photoconductive semiconductor sensing element. This invention relates to an improvement in an infrared detector that uses an amplifier to amplify and output a signal generated by human input.

The configuration of the main parts of the infrared detector is shown in FIG. 4, in which the photoconductive semiconductor sensing element 1 is attached to the vacuum side of the upper part of the cavity 22 in a cylindrical vacuum part 21 having a cavity 22. Therefore, liquid cryogen, J-T cooler, i-ring type cooler, etc. are used to cool the temperature to about 77 to 90 degrees Celsius, and the temperature change is kept to about 1 degree or less.

Further, infrared rays are transmitted through the infrared transmitting window 20, and an imaging signal is output by utilizing the fact that the resistance changes when the infrared rays hit.

[Conventional technology]

FIG. 5 is a block diagram showing the circuit configuration of the main parts of a conventional infrared detector, and FIG. 3 is a diagram showing changes in resistance and responsivity with respect to temperature changes of an example of a photoconductive semiconductor sensing element. .

The case in FIG. 5 is an example of a photoconductive semiconductor sensing element array 10 having five photoconductive semiconductor sensing elements,
The current flowing through each photoconductive semiconductor sensing element 1-1 and the photoconductive semiconductor sensing elements 1-1 to 1-5 is a constant current, and the resistance changes when infrared rays are applied to output an imaging signal. I have to.

In order to amplify and output the generated signal voltage, an amplifier 11 is provided for each of the photoconductive semiconductor sensing elements 1-1 to 1-5.

[Problem to be solved by the invention]

However, even if the temperature of the photoconductive semiconductor sensing element 1 is controlled to be constant, there are cases where the temperature changes by about 1 degree.

On the other hand, since the photoconductive semiconductor sensing element l is a semiconductor,
When the temperature changes, the carrier concentration and the electron mobility change, and as shown in Figure 3 (A), the resistance of several tens of ohms decreases with respect to the temperature in the range of 1 degree change near the operating temperature of 77 to 90. Changes linearly.

When the resistance changes, since the photoconductive semiconductor sensing element 1 operates with a constant current, the voltage across the element 1 changes and noise is generated.

Furthermore, when the temperature changes, the responsivity of the photoconductive semiconductor sensing element 1, expressed as the signal voltage/incident power, changes to, for example, 4 to 5 XlO'V at the operating temperature of 77 to 90°C.
/W, and within a temperature range of 1 degree, the value changes linearly, causing noise.

That is, there is a problem in that noise occurs even when the temperature changes by about 1 degree.

An object of the present invention is to provide an infrared detector that can suppress noise even if there is a temperature change of about 1 degree at the operating temperature.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, a high resistance 2 is connected in series to a photoconductive semiconductor sensing element 1, which is an image sensor, and a voltage is applied to both ends by a voltage generating means to cause a constant current to flow. In an infrared detector that amplifies and outputs a signal generated by inputting infrared rays to a semiconductor sensing element 1 using an amplifier, a temperature sensor 3 is provided to detect temperature changes of the photoconductive semiconductor sensing element 1 without delay, The voltage generating means is a variable voltage generating means 4 that recognizes the temperature detected by the temperature sensor 3 and generates a voltage that keeps the voltage across the photoconductive semiconductor sensing element l constant even if there is a temperature change. and the amplifier has a variable gain that recognizes the temperature detected by the temperature sensor 3 and cancels changes in the signal voltage caused by temperature changes even if the voltage across the photoconductive semiconductor sensing element 1 is kept constant. This is referred to as control amplification means 5.

[For production]

In the present invention, voltage changes due to resistance changes of the photoconductive semiconductor sensing element 1 and voltage changes due to responsivity changes are determined in advance in a range where temperature changes occur.

The temperature change in the photoconductive semiconductor sensing element 1 is detected without delay by the temperature sensor 3, and is notified to the variable voltage generation means 4 and the variable gain control amplification means 5.

The variable voltage generating means 4 determines, at what temperature, how much voltage should be generated to keep the voltage across the photoconductive semiconductor sensing element 1 constant by changing the voltage due to the above resistance change determined in advance. is predetermined and the predetermined voltage is generated in accordance with the temperature detected by the temperature sensor 3. Therefore, when the temperature changes, the variable gain control amplification means 5 will be able to generate the predetermined voltage depending on the change in the responsiveness determined in advance. By changing the signal voltage, the gain of the variable gain control amplification means 5 is determined in advance so that the output does not change at any given temperature. Since the gain is set to a predetermined value, the output of the variable gain control amplification means 5 remains constant even if the temperature changes, so that noise caused by changes in responsivity can be suppressed.

〔Example〕

FIG. 2 is a circuit diagram of a main part of an infrared detector according to an embodiment of the present invention.

The difference in FIG. 2 from the conventional example shown in FIG. The difference is that the variable gain amplifier 5-1 whose gain changes according to the above and the temperature-recognized gain variable resistance value changing section 5-2 which changes the resistance value are used, and the following description will focus on these different points.

In the present invention, when the temperature changes in the range of 1 degree at the operating temperature of 77 to 90 degrees, the voltage changes due to the resistance change of the photoconductive semiconductor sensing element 1-1 and the signal voltage changes due to the responsivity change. Let's find out.

The temperature sensor 3 is composed of a temperature sensor such as Si or a photoconductive semiconductor sensing element that can monitor the temperature at the same rate of change as the photoconductive semiconductor sensing element l-1, and as shown in FIG. It is attached near the sensing element 1, and the monitored temperature value is notified to the temperature recognition section 4-1 and the temperature recognition gain variable resistance value changing section 5-2.

The variable voltage generator 4-2 is set in advance so that the operating temperature is around 77 to 90 degrees and the temperature change is in the range of 1 degree, for example, 0,1 degree.
It is predetermined in advance how much the generated voltage should be to keep the voltage across the photoconductive semiconductor sensing element 1-1 constant based on the voltage change due to the previously determined resistance change when the voltage changes.

When the temperature recognition unit 4-1 recognizes the temperature from the temperature sensor 3, a predetermined voltage corresponding to this temperature is generated from the variable voltage generator 4-2, and the photoconductive semiconductor sensing element 1 Keep the voltage across -1 constant.

In this way, even if the temperature changes, voltage changes across the photoconductive semiconductor sensing element it are suppressed, so noise caused by resistance changes can be suppressed.

Further, a resistance value that changes the gain is determined in advance to determine whether the above-determined stress force does not change when the temperature changes within a range of 1 degree, for example, by 0.1 degrees at the operating temperature.

Then, in the temperature recognition gain variable resistance value changing section 5-2,
The temperature from the temperature sensor 3 is recognized, and a previously determined resistance value corresponding to that temperature is selected.

Then, the output of the variable gain amplifier 5-1 becomes one in which noise due to responsivity changes is suppressed.

〔Effect of the invention〕

As explained in detail above, according to the present invention, 1
This has the effect of suppressing noise even when there is a temperature change of about 100 degrees.

[Brief explanation of drawings]

Figure 1 is a diagram of the principle of the present invention. Figure 2 is a circuit diagram of the main parts of an infrared detector according to an embodiment of the present invention. Figure 3 is an example of the resistance value of a photoconductive semiconductor sensing element against temperature change. FIG. 4 is a structural diagram of the main parts of an example of an infrared detector, and FIG. 5 is a block diagram showing the circuit configuration of the main parts of a conventional infrared detector. In the figure 1. 1-1 to 1-5 are photoconductive semiconductor sensing elements 1.2-1
~2-5 is a high resistance, is a temperature sensor, is a variable voltage generation means, -1 is a temperature recognition section, -2 is a variable voltage generator, is a variable gain control amplification means, -1 is a variable gain amplifier, -2 is a variable voltage generator 0 is a photoconductive semiconductor sensing element array, 0 is an infrared transmitting window, 1 is a vacuum portion, and 2 is a cavity. 2 C & Sun Moon A? □ Part (2)

Claims (1)

[Claims] A high resistance (2) is connected in series to a photoconductive semiconductor sensing element (1) which is an image sensor, and a voltage is applied to both ends by a voltage generating means to cause a constant current to flow. In an infrared detector that amplifies a signal generated by inputting infrared rays to a photoconductive semiconductor sensing element (1) using an amplifier and outputs the signal, the temperature change of the photoconductive semiconductor sensing element (1) is detected without delay. A temperature sensor (3) is provided, and the voltage generating means recognizes the temperature detected by the temperature sensor (3), and even if there is a temperature change, the temperature at both ends of the photoconductive semiconductor sensing element (1) is controlled. Variable voltage generation means (4) that generates a voltage that keeps the voltage constant
), and the amplifier recognizes the temperature detected by the temperature sensor (3), and even if the voltage across the photoconductive semiconductor sensing element (1) is kept constant, the signal voltage generated by the temperature change will change. An infrared detector characterized by comprising variable gain control amplification means (5) for canceling out.