JPS606746Y2 - Temperature signal amplitude automatic adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic temperature signal amplitude adjustment device for a thermography apparatus that optically scans an object and displays an infrared image of the object on a cathode ray tube.

In a thermography device, an object is optically scanned, infrared rays from the object are detected through the scanning, and the detected signal is controlled such as level and amplitude, and then used as a brightness modulation signal for a cathode ray tube. However, the electron beam is scanned in synchronization with the above scanning, and an infrared image of the subject is displayed on the cathode ray tube.

The contrast and brightness of the infrared image displayed on the cathode ray tube screen must be suitable for visual observation or photographic observation.

Conventionally, the temperature signal amplitude that determines this contrast is adjusted by changing the cathode voltage of the cathode tube while an operator observes the image of the subject displayed on the cathode ray tube and parts other than the image. Individual differences among operators were likely to occur.

The present invention has been made to solve these drawbacks, and provides a new temperature signal amplitude automatic adjustment device for a thermography apparatus.

FIG. 1 is a block diagram of an automatic temperature signal amplitude adjustment device showing an embodiment of the present invention.

In the figure, block 1 indicated by a dashed line is a background temperature signal generation circuit for generating background temperature, which includes a series circuit of switch 6, diode 8, voltage generator 9, switch 10, and capacitor 33, switch 12, and Warning from storage circuit 13.

4 is a scanning signal generation circuit, 11 is a one-shot multivibrator that generates a pulse based on the vertical retrace signal generated by the circuit, and 21 is a one-shot multivibrator that generates a pulse when the pulse from the vibrator falls. .

Switch 1 of the background temperature signal generation circuit 1
0 is instantaneously turned on by a start means (not shown) that operates in synchronization with the operation of the power supply when the device is turned on, and immediately returns to the off state, after which the signal of the vibrator 21 is turned on. When the switch is turned on, the capacitor 33 is charged with the voltage from the voltage generator 9.

This voltage can be of any value. A circuit 5 generates a signal that turns off the switch 6 of the background temperature signal generation circuit 1 when the horizontal retrace signal and vertical retrace signal generated by the scanning signal generation circuit 4 are supplied. Occur.

the switch is in an on state during the first field scan;
When in the on state, a temperature signal is supplied to the diode 8 from the optical scanning mechanism LS through the switch.

Since the diode is connected in the opposite direction to the supplied signal, it allows the signal to pass only when the voltage is lower than the charging voltage of the capacitor 33.

Therefore, during the first field scan, the capacitor is charged with voltage values corresponding to successively smaller temperature signals.

Switch 1 of the background temperature signal generation circuit 1
2 is turned on when the vertical retrace signal from the scanning signal generating circuit 4 is supplied via the one-shot multivibrator 11, so that the first field and the second field
During the vertical retrace period with the field, the lowest voltage of the screen at the end of the first field, which is charged in the capacitor 33, is stored in the storage circuit 13 via the switch.

The output of the storage circuit corresponds to the background temperature signal.

A block 3 indicated by a dashed dot line is a circuit 3 for creating an average temperature of an effective object, and a switch 32, an integrator 19 to which the switch 22 is connected in parallel, and a block 3 in the retrace period of the first field scan.
It consists of a divider circuit 18, a switch 34, an accumulation circuit 35, an integrator 17, a switch 15, and a constant voltage generator 16.

14, a background temperature signal created by the background temperature signal creation circuit 1 is supplied as a reference signal to a positive terminal, and a temperature signal from the intestine of the optical scanning mechanism is supplied to a negative terminal, and the negative terminal The switches 32 and 15 of the average temperature generating circuit 3 are scanned during second field scanning of the temperature signals that are higher than the reference signal among the temperature signals supplied to the
and a comparator that supplies signals to the switch 23, respectively.

That is, the comparator generates a signal for extracting the effective object scanning period during the second field scanning.

First, the switch 15 remains on while the output is being supplied from the comparator, so during this time the voltage from the constant voltage generator 16 is sent to the integrator 17.

This constant voltage is the voltage used to calculate the effective area of the subject.
A voltage value that becomes full scale when the area is 100% is set.

The integrator integrates the voltage from the constant voltage generator 16 and sends it to the divider circuit 18.

This integrated value corresponds to the area of the effective subject.

Further, while the switch 32 is in the on state, the optical scanning mechanism L
The effective object temperature signal from S is integrated by the integrator 19 via the switch, and the integrated signal is supplied to the divider circuit 18.

The integral value is the sum of the temperatures of the entire effective object.

The division circuit divides the integral value of the temperature signal by the integral value of the constant voltage.

Therefore, the divided signal is the average temperature signal of the valid object.

Since the switch 34 remains on while the signal is being supplied from the one-shot multivibrator 11, the average temperature signal of the effective object from the divider circuit 18 is sent to the storage circuit 35 via the switch 34. Accumulated.

20 is a differential amplifier whose positive terminal is supplied with the temperature signal from the optical scanning mechanism, and whose negative terminal is supplied with the average temperature signal of the effective object from the storage circuit 35, and the average temperature of the effective object is set as the center temperature level. Output a signal.

29 is the differential amplifier 20, where Va is the temperature signal from the optical scanning mechanism 6 supplied to the positive terminal of the differential amplifier 20, and Vc is the center temperature from the average temperature generation circuit 3 to the negative terminal. The output signal (Va-Vc) of the amplifier 20 is an output adjustment circuit that operates so that the center temperature Vc is the center of the brightness level.

The switch 22 connected in parallel to the integrator 19 of the average temperature generating circuit 3 is connected to the one-shot multivibrator 2.
The integrator 19 is turned on by a pulse signal from the integrator 19, and discharges the charge stored in the capacitor of the integrator 19.

The output signal of the output adjustment circuit 29 is supplied to the peak rectification circuit 24 through the switch 23, which remains on during the effective object scanning period.

The peak rectifier circuit takes the difference between the maximum temperature value and the minimum temperature value of the effective object, that is, the peak-to-peak value, and outputs the difference to the storage circuit 2.
Send to 5.

The switch 26 is the one-shot multivibrator 1
When the switch 25 is in the on state, the signal accumulated in the storage circuit 25 is supplied to the signal amplitude discrimination circuit 27 via the switch 26.

The signal amplitude discrimination circuit discriminates the magnitude of the amplitude of the difference signal (peak-to-peak value) between the maximum temperature value and the minimum temperature value from the peak rectifier circuit during the vertical retrace period of the second field and the third field. , which controls the temperature range switching circuit 28.

The switching circuit, according to the signal value from the discrimination circuit 27,
The amplitude of the temperature signal (Va-Vc) from the output adjustment circuit 29 is adjusted and supplied to the cathode of the cathode ray tube BT.

Note that 30 and 31 are switches for the peak rectifier circuit 24 and the storage circuit 25, respectively, which are turned on by the pulse of the one-shot multivibrator 21, and when in the on state, the capacitors of the peak rectifier circuit and the Discharges the charge accumulated in the capacitor of the accumulation circuit.

Further, in the above embodiment, a variable reference voltage source may be provided as the background temperature signal generating circuit 1 and may be switched off so as to be supplied to the positive terminal of the comparator 14.

In such an apparatus, during the first field scan, the background temperature signal generation circuit 1 generates a background temperature, and the generated background temperature signal is stored in the storage circuit 13 of the background temperature signal generation circuit 1. to the positive terminal of the comparator 14.

Since the negative terminal of the comparator is supplied with a temperature signal from the optical scanning mechanism ratio, the comparator
During the second field scan, a temperature range higher than the background temperature signal is extracted and supplied to the switch 15, 32 and the switch 23 of the effective object average temperature generation circuit 3 during the extraction period, that is, during the effective object scanning period.

The average temperature generating circuit 3 generates a temperature signal excluding the background temperature signal among the temperature signals from the optical scanning mechanisms I and S, that is, an average temperature Vc of the temperature signal of only the effective subject.
is generated, and the average temperature signal Vc is supplied to the negative terminal of the differential amplifier 20 from the storage circuit 35 of the average temperature generation circuit.

Since the positive terminal of the amplifier is supplied with the temperature signal Va from the optical scanning mechanism LS, the amplifier receives the difference (V
a-Vc) to the output adjustment circuit 29.

On the other hand, during the effective object scanning period, the output adjustment circuit 29
The output signal of is passed through the switch 23 to the peak rectifier 24
supplied to

The rectifier determines the difference (peak-to-peak value) between the highest temperature value and the lowest temperature value of the signal from the output adjustment circuit 29 and supplies the difference signal to the storage circuit 25 .

During the vertical retrace period from the second field to the third field,
The signal accumulated in the accumulation circuit is supplied to an amplitude discrimination circuit 27, where the magnitude of the amplitude of the difference signal is discriminated.

Based on the determination, the determination circuit selects a temperature range switching circuit 28.
The amplitude of the signal (Va - Vc) from the differential amplifier 29 is controlled to be switched to the most appropriate magnitude.

The amplitude-adjusted signal is supplied to the cathode of the cathode ray tube BT, so that the contrast and brightness of the infrared image on the cathode ray tube are appropriately adjusted.

According to this invention, the temperature range is automatically controlled using the temperature signal from only the subject on the CRT screen, so regardless of the temperature difference between the subject and other parts, the optimum contrast infrared image is always obtained. is obtained, and individual differences between operators do not occur.

[Brief explanation of the drawing]

The attached figure is a block diagram of an automatic temperature signal amplitude adjustment device showing an embodiment of the present invention. 1: Background temperature signal generation circuit, 3: Average temperature generation circuit, 14: Comparator, 20: Differential amplifier, 2
4: peak rectifier circuit, 25: storage circuit, 27: amplitude discrimination circuit, 28: temperature width switching circuit.

Claims (1)

[Scope of utility model registration request] In a device that optically scans a subject, detects infrared rays from the subject, and adjusts the amplitude of this signal in the process of supplying the detected temperature signal to a display device, the device optically scans the subject. Means means for creating an average temperature signal of the temperature signal of the subject excluding the background from among the temperature signals obtained by scanning the subject, a temperature obtained by subtracting the average temperature signal from the temperature signal obtained by optically scanning the subject; A temperature signal amplitude characterized by comprising means for determining a peak-to-peak value of a signal, and means for determining the magnitude of the amplitude of the peak-to-peak value and adjusting the amplitude of the difference signal to an arbitrary magnitude. Automatic adjustment device.