JPS5945946B2 - Automatic brightness correction circuit for cathode ray tube radar display equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic brightness correction circuit for a radar display device using a cathode ray tube (hereinafter referred to as CRT).

A conventional brightness correction circuit of this type is shown in FIG.

In the figure, 1 is a CRT, and 2 is a CRT that amplifies the brightness modulation signal.
Luminance modulation waveform amplification circuit added to grid G of RTl, 3
4 is a brightness adjustment circuit for outputting the brightness modulation signal, 4 is a brightness adjustment variable resistor of the brightness adjustment circuit 3, and 5 is a video amplifier circuit for applying a video signal to the cathode K of the CRTl.

FIG. 2 shows the operating waveforms of the device shown in FIG. 1, where 6 is the radar trigger pulse, 7 is the CRT1 sweep waveform, and 8 is the CR
9 shows the cathode waveform of Tl and the grid waveform of CRTl.

Next, the operation will be explained.

In this device, the brightness of the emission line on the CRTl is
is determined by the potential difference between the cathode K and the grid 0.

The cathode of the CRTI is supplied with the voltage +V1 of the cathode waveform 8 which is the output of the video amplifier circuit 5, and the grid G is supplied with the voltage - of the grid waveform 9 which is the output of the luminance modulation waveform amplifier circuit 2.
It has a voltage of V2.

The brightness of the sweep line on the CRTl can be adjusted by changing the voltage amplitude V3 of the grid waveform 9 using the brightness adjustment variable resistor 4 and the brightness adjustment circuit 3.

In conventional circuits of this type, the brightness of the sweep line on the CRTl is only artificially determined by the brightness adjustment variable resistor 4, as described above, so the CRTl is rotated in response to the rotation of the antenna. The brightness of the swept line is affected by the rotational speed of the antenna, and the brightness on the CRTl increases as the rotational speed decreases.

In particular, since the brightness increases extremely when the antenna is stopped, there is a drawback that the brightness adjustment variable resistor 4 must be adjusted each time.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and detects the minimum bit LSB of a digital angle signal expressing the angular position of the antenna, and converts the rate of change of this data into an analog voltage. It is an object of the present invention to provide an automatic brightness correction circuit that is added to a brightness adjustment circuit to automatically control the brightness of a bright line on a CRT in accordance with the rotational speed of an antenna.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows an automatic brightness correction circuit according to one embodiment of the present invention.

In the figure, 1 to 5 indicate the same things as in Figure 1, and 10
1 is an antenna, 11 is a digital angle signal generator that generates a digital signal representing the angle of the antenna 10, and 12 is a digital angle signal generator 11 that converts the frequency of the minimum angle signal LSB, that is, the rotational speed of the antenna 10, into an analog voltage. Frequency and voltage converter (hereinafter referred to as F/V converter)
FIG. 4 shows the human output characteristics of this F/V converter 12.

In the above, the digital angle signal generator 11 and F
/V converter 12 constitutes a rotation speed detection circuit 13 that detects the rotation speed of antenna 10.

Next, the operation will be explained.

Antenna 100 angle signal is generated by digital angle signal generator 11
appears as the output of

By inputting the minimum angle signal LSB of this digital signal to the F/V converter 12, an analog voltage according to the input/output characteristics shown in FIG. 4 can be obtained.

That is, as the antenna rotation speed increases, the output analog voltage also increases proportionally.

Therefore, by inputting this analog voltage to the brightness adjustment circuit 3 and subtracting it from the voltage determined by the brightness adjustment variable resistor 4, a corrected voltage amplitude 3' as shown in the grid waveform 9 in FIG. 5 can be obtained5. This voltage amplitude V3'
Since it increases or decreases depending on the voltage amount of the analog voltage (4), that is, the rotational speed of the antenna, the potential difference between the grid G1 cathode and the CRT1 automatically changes depending on the rotational speed of the antenna.

As a result, the brightness of the bright line on the CRTl is automatically adjusted in accordance with the rotational speed of the antenna.

In addition, in the embodiment described in i, the antenna rotation speed detection signal was the minimum bit of the digital angle signal, but in the case of analog angle display using a synchro oscillator, etc., the output of the tacho generator of the antenna drive motor may be used. 3. As described above, according to the present invention, the brightness on the CRT is automatically changed according to the rotational speed of the antenna, so the brightness can be artificially changed according to the change in the rotational speed. It is not necessary to install the circuit each time, and the circuit configuration can be realized relatively easily and inexpensively by simply adding an F/V converter to the conventional circuit.

Moreover, this circuit can be expected to be particularly effective when taking pictures of CRT surfaces.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a brightness adjustment system of a conventional CRT display device, Fig. 2 a - d are operational waveform diagrams of Fig. 1, and Fig. 3 is an automatic brightness correction of a CRT display device according to an embodiment of the present invention. FIG. 4 is a block diagram of the circuit, FIG. 4 is an input/output characteristic diagram of the F/V converter shown in FIG. 3, and FIGS. 5 a to 5 d are operation waveform diagrams of FIG. 3. 1...CRT, 2...Brightness modulation waveform amplification circuit, 3.
...Brightness adjustment circuit, 4...Variable resistor for brightness adjustment, 10
...Antenna, 13...Rotation speed detection circuit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a radar display device using a cathode ray tube, there is a rotation speed detection circuit that detects the rotation speed of the antenna, and a brightness that changes the voltage amplitude of the grid waveform based on the output of this rotation speed detection circuit and the output of a variable resistance for brightness adjustment. An automatic brightness correction circuit for a cathode ray tube radar display device, comprising: an adjustment circuit; and a brightness modulation waveform amplification circuit that amplifies the output of the brightness adjustment circuit and adds it to the grid of the cathode ray tube.