JPS61118628A - Infrared video apparatus - Google Patents

Abstract

PURPOSE:To obtain an optimum luminance level, by comparing the DC level, which was detected by adding the amplified outputs of a plurality detection circuit, with a predetermined level to obtain a difference signal and reversing said difference signal to add the same to the prescribed level of each clamp circuit. CONSTITUTION:The images of the positions 11-1n of objective matter 1 are picked up to be inputted to the detection elements 31-3n of a multielement detection circuit 3. The outputs of the detection elements 31-3n are amplified by amplifying circuits 61-6n to be inputted to a display part 7. THe outputs of the amplifying circuits 61-6n are added by an adder 91 and a DC level is detected by a detector to be compared with reference voltage by comparator 93 and the difference voltage is reversed by a reversal circuit 94 and amplified by an amplifying circuit 95 to be superposed to the DC set voltage of a level setting circuit 8. The voltage signals obtained by superposition are outputted to the clamp circuits 51-5n. The DC level of video signal receives negative feedback to be suppressed in level variation. By this method, an optimum luminance level is always obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an infrared imaging device that has a multi-element detector and displays a video signal obtained by photoelectrically converting infrared rays emitted from a target object, and particularly relates to an infrared imaging device that has a multi-element detector and displays a video signal obtained by photoelectrically converting infrared rays emitted from a target object. This invention relates to an infrared imaging device that has been improved to suppress DC level fluctuations and maintain a constant display brightness level.

An infrared imaging device captures infrared rays emitted from a target object by scanning the imaging unit, converts the captured infrared rays into a video signal by photoelectrically converting it with an infrared detector, and processes this video signal to display it on the display unit. The target object is displayed as an infrared image pattern using a cathode ray tube or LED.

In an infrared imaging device using a multi-element detector that photoelectrically converts infrared rays from the scanning position of a target object using a multi-element detector, and synthesizes the video signals converted by each detection element and displays it as a video pattern. If there is variation in the DC level of the output video signal of each detection element, uneven brightness will occur in the video pattern displayed on the display section, and a clear display of the pattern image will not be obtained. Therefore, in order to prevent unevenness in the brightness of the video pattern, a clamp circuit is provided at the output end of each sensing element to clamp the DC level of the output video signal of each sensing element at a predetermined level, thereby aligning the video signal above a certain level. This prevents uneven brightness due to DC level fluctuations.

However, due to the temperature of the environment in which the infrared imaging device is installed, changes in the gain of the device's amplifier circuit, changes in the polarity of the video signal, and inverted display may cause DC level fluctuations in the video signal, resulting in changes in brightness. occurs. Conventionally, in order to eliminate this change in brightness, the operator has to adjust the set voltage of the clamp circuit each time, which requires considerable effort. Therefore, there has been a demand for an infrared imaging device that does not require such manual adjustment, automatically keeps the DC level of the output video signal of each element constant, and always provides an optimal brightness video pattern.

[Conventional technology]

FIG. 3 is a block diagram of an infrared imaging device using a conventional multi-element detector. In the figure, an imaging unit 2 captures infrared rays emitted from positions 11 to 1n of a target object 1, condenses the infrared rays, and makes the infrared rays enter each detection element of a multi-element detector disposed at a focal point. That is, the infrared rays at position 11 enter the sensing element 31, the infrared rays at position 1n enter the sensing element 3n, and so on, which are arranged in correspondence with the imaging positions. Once the infrared rays at the vertical position shown in the figure are captured, the infrared rays from one side of the target object are sequentially captured as the imaging unit 2 horizontally scans.

The infrared rays at each vertical position incident on the elements 11 to In are photoelectrically converted into a video signal by a detection element corresponding to the position. The converted video signals are input to preamplifiers 41 to 4n, amplified, and input to clamp circuits 51 to 5n, respectively. The clamp circuits'@51 to 5n clamp the DC component of the video signal using the DC voltage V set by the level setting circuit 8 to align the video signal above a certain level. The output video signal of the clamp circuit is input to the display section 7 via the amplifier circuits 61 to 6na. The display unit 7 processes the input video signal and displays it on a cathode ray tube or L.
Display the temperature pattern of the target object on ED.

[Problem that the invention seeks to solve]

In the conventional infrared imaging device mentioned above, the amplification circuit of the device may vary depending on the temperature of the installation environment of the infrared imaging device.
Changes in the DC level of the video signal occur when the i-path gain is changed, the polarity of the video signal is switched, and the display is inverted, and the brightness changes due to the DC level fluctuation. Therefore, in the past, the operator adjusted the DC setting voltage of the level setting circuit each time to eliminate the change in brightness, which required frequent adjustment and labor.

[Means for solving problems]

The present invention provides an infrared imaging device that solves the above problems, and includes a plurality of sensing elements that scan a target object and capture infrared rays at the scanned position, and an output signal of each of the sensing elements. In an infrared imaging device comprising a clamp circuit that regulates a DC level to a predetermined level, and in which the brightness level of an image is set by each of the clamp circuits, the output signals of the respective clamp circuits are added together to detect the DC level of the added signal. An infrared ray comprising a detection means, a comparison circuit for comparing an output DC level of the detection means with a predetermined level, and a circuit for superimposing brightness adjustment based on the output of the comparison circuit on the specified level of the clamp circuit. Made by video equipment.

[Effect]

The above-mentioned infrared imaging device adds the output video signals of each detection element of the multi-element detector using an adder circuit, detects the DC voltage of the output added signal of the adder circuit using a direct current (DC) level detection circuit, and detects the detected DC voltage. and a DC set voltage of a predetermined value are compared by a comparator circuit to detect the difference value, and the polarity of the detected DC voltage is inverted by an inverting circuit and superimposed on the clamp voltage of the DC level detection circuit to detect each detection element. Corrects fluctuations in the DC voltage of the video signal. In other words, when the DC level of the video signal increases, it is suppressed, and when it decreases, it is expanded, and the brightness of the display section is always constant.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an infrared imaging device using a multi-element detector according to an embodiment of the present invention, FIG. 2 is a block diagram of essential parts of an infrared imaging device according to an embodiment of the invention, and FIG. The same parts are indicated by the same symbols.

As shown in the block diagram of FIG. 1, the infrared imaging device of the present invention provides a DCC circuit for the video signals of the amplification circuits 61 to 6n at the output terminals of the amplification circuits 61 to 6n of the conventional infrared imaging device shown in FIG. Adding circuit 91 as a detection means for level detection
and a DC level detection circuit 92, and a comparison circuit 93 that compares the detected DC voltage of the DCC level output circuit 92 and a set DC voltage of a predetermined value and outputs the difference voltage, and the output difference of the comparison circuit 93. An inverting circuit 94 is added to invert the polarity of the voltage and superimpose it on the DC setting voltage of the level setting circuit 8.

The operation is such that the output video signal representing the temperature at the vertical position of the target object outputted from the amplifier circuits 61 to 6n is sent to the adder circuit 9.
1 is input. The adding circuit 91 adds up each input video signal and outputs the result to the DC level detection circuit 92. The DC level detection circuit 92 detects the DC voltage of the added video signal and outputs it to the comparison circuit 93. The comparison circuit 93 compares the detected DC voltage inputted with reference to a set voltage v1 built into the comparison circuit, and if the detected DC voltage is larger than the set voltage v1, it compares the DC voltage corresponding to the magnitude, and if it is the opposite, it compares the detected DC voltage. Outputs the difference voltage between one DC voltage. ” Comparison circuit 9
The set voltage v1 built into the display unit 3 is set to a value that makes the brightness of the display section optimal. The output DC difference voltage of the comparator circuit 93 is inputted to an inverting circuit 94, the polarity of which is inverted, and the output DC difference voltage is inputted to an inverting circuit 94.
5 is amplified by a predetermined amount, superimposed on the clamp DC voltage of the clamp setting circuit 8, and output to each clamp circuit 51 to 5n.

As a result, the DC level of the video signal forms a negative feedback loop, and the deviation between the DC level of the video signal and the set level is suppressed to 1/2 of the lube gain, and the brightness for optimal display is always obtained. Become.

〔Effect of the invention〕

As explained above, according to the present invention, by forming and adding a negative loop to an infrared imaging device, fluctuations in the DC level of the video signal are suppressed, and the display brightness level is kept constant at an optimal value. This has the effect of eliminating the need to frequently manually adjust the brightness level.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an infrared imaging device using a multi-element detector according to an embodiment of the present invention, FIG. 2 is a block diagram of main parts of an infrared imaging device according to an embodiment of the present invention, and FIG. 3 is a conventional one. FIG. 2 is a block diagram of an infrared imaging device using a multi-element detector. In the figure, 1 is a target object, 11 to 1n are positions of the target object, 2 is an imaging unit, 3 is a multi-element detector, 31 to 3n are detection elements, 41 to 4n are preamplifiers, 51 to 5n are clamp circuits, 61 6n, 95 is an amplifier, 7 is a display section, 8 is a level setting circuit, 91 is an addition circuit, 92 is a DC level detection circuit, 93 is a comparison circuit, and 94 is an inversion circuit.

Claims (1)

[Claims] It is equipped with a plurality of detection elements that scan a target object and capture infrared rays at the scanning position, and a clamp circuit that regulates the DC level of the output signal of each of the detection elements to a predetermined level, and the brightness level of the image is adjusted by each of the clamp circuits. In the infrared imaging device, the infrared imaging device includes: a detection means for adding the output signals of the respective clamp circuits and detecting the DC level of the added signal; a comparison circuit for comparing the output DC level of the detection means with a predetermined level; An infrared imaging device further comprising a circuit for superimposing and applying a brightness adjustment voltage based on the output of the comparison circuit to the specified level of the clamp circuit.