JPS5820184B2 - Kaidan TV News - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a staircase wave television signal that can be used in cases where a plurality of distorted images having different brightness are sequentially displayed on the screen of a television receiver to be useful for various adjustments and measurements. Regarding the generator.

When measuring the linearity of a video circuit in a television receiver or gamma characteristics of a cathode ray tube, it is necessary to generate a staircase wave television signal and apply it to the television receiver. A plurality of distorted images with different brightnesses are sequentially projected from left to right or top to bottom on the top, and their brightness etc. are measured.

However, because an ordinary television receiver performs overscanning at ℃, the distorted image at the edge of the screen where the brightness is 1 to 2 steps becomes invisible and cannot be measured. Moreover, in cathode ray tubes, the brightness differs between the center and the edges of the screen, and there is a convergence shift, so if the position of the distorted image is always constant, the distorted image of every brightness step will be distorted. However, there is a disadvantage that accurate measurements cannot be made.

Therefore, it would be better to be able to move the position of the distorted image so that, for example, the distorted image with steps of arbitrary brightness can be positioned in the center of the screen, but this type of conventional staircase wave television signal The generator generates a sawtooth wave signal using a synchronization signal as a reference, and based on this, a staircase wave television signal is generated, so the brightness step and the position of the distorted image are changed. There was an inconvenience in not being able to do so.

Also, even if the position can be changed, the distorted image will not be displayed during the blanking period after changing the position.
There was an inconvenience that the brightness step would jump.

Therefore, the present invention solves such conventional disadvantages, makes it possible to arbitrarily and easily change the position of the distorted image of steps of different brightness, and also prevents the brightness steps from jumping during the blanking period. The purpose of this invention is to provide a staircase wave television signal generation device that does not require a staircase wave, and for this purpose, a clock pulse generation circuit such as a locked oscillator that stops generating clock pulses during the blanking period, and a clock pulse generation circuit that stops generating clock pulses during the blanking period. A counter that counts and generates a binary output for generating a staircase wave, a reset circuit that resets this counter at the IH cycle, and a D-
The present invention is characterized by comprising a D-A converter that performs A conversion into a staircase wave television signal.

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

First, in Fig. 1, 1 is a synchronization signal generation circuit,
In addition to the horizontal blanking pulse as shown in FIG. 2A, a vertical synchronizing signal, a horizontal synchronizing signal, etc. are generated.

A locked oscillator 2 whose operation is controlled by this horizontal blanking pulse A stops oscillation during the blanking period and generates clock pulses at a rate of 11 during IH as shown in FIG. 2B.

Further, reference numeral 3 designates a counter which receives this clock pulse B as an input, counts it, and generates a binary count output such as 4-bit staircase wave generation such as E, F, and G.

This counter 3 is reset every IH by a reset pulse as shown in FIG. 2C generated from a reset circuit 4 in order to determine the position of the distorted image to be displayed.

This reset circuit 4 is, for example, as shown in FIG. A pulse is selected and taken out in the forming circuit 8, and a reset pulse C is generated as a narrow pulse.

The counter 5 of the reset circuit 4 is reset using a signal in which the blanking pulse A is inverted and the width of the pulse is narrowed by the shaping circuit 9.

As a result, the counter 3 generates a count output based on the position of an arbitrary clock pulse B.

The binary output of the counter 3 is applied to a D/A converter 10, where the binary output is D/A converted to generate a staircase wave television signal as shown in FIG. 2H.

This makes it possible to display 11 distorted images by dividing the brightness from the white level to the black level into 11 steps.

When using a staircase wave television signal as shown in Fig. 2H, the brightest distorted image is displayed at the left end of the screen, and then the narrower distorted images are displayed sequentially starting from the darkest distorted image. It will be possible.

Furthermore, as is clear here, by changing the position of the reset pulse C in the reset circuit 4, the position of the distorted image can be shifted, and a distorted image with arbitrary brightness steps can be displayed in the center of the screen. I can do it.

Moreover, since no clock pulse is generated from the locked oscillator 2 during the blanking period, the brightness step will not jump during this period, and when returning from one end of the screen to the other, the brightness will change by one step. This means that all steps can be displayed.

Note that 11 is an amplification/mixing circuit that amplifies the output signal and further adds a synchronization signal, and 12 is an output terminal.

In addition, 13 in the figure indicates that the area where this distorted image is displayed is limited to only a part of the screen as shown in Figure 4, and the brightness of the other areas is adjusted based on the brightness of the rightmost part of the distorted image. This is a circuit for changing the brightness several levels brighter than the blanking signal A or the horizontal synchronizing signal by counting the blanking signal A or the horizontal synchronizing signal by a counter 14 that is reset every field by the vertical synchronizing signal. The beginning and end of the one-fifth period are detected, and the output sets and resets the 7-lip-flop 15 to generate a pulse only during this period, and this pulse is applied to the AND gate 16 to generate the clock pulse B only during this period. is transmitted to the counter 3, and in addition to the brightness control circuit 17, an arbitrary binary output selected by the switch 18 is generated from the brightness control circuit 17 during the other 4/5 period, By adding this to the DA converter 10 via OR gates 19 to 22, the output of the counter 3 becomes E.

If any of F and G is 0"', the output of "1" from the brightness control circuit 17 is selectively added to the corresponding OR gates 19 to 22, thereby calculating the logical sum of the outputs of both. Then, based on the output of counter 3 at that time, that is, the brightness at the right end of the distorted image, it is possible to change the brightness of the remaining 4/5th part to several levels brighter than that. ing.

By changing the ratio between the two and the brightness of other parts, the average brightness level (APL) of the screen can be changed, which can be used to measure DC transmission rate and the like.

The brightness control circuit 1T may be constructed of a logic circuit, or many digital switches may be used as the switch 18, and the output of the switch 18 may be converted into a binary output.

Further, the AND gates 23 to 26 are for cutting off input to the DA converter 10 during the blanking period.

In the above embodiment, a case has been described in which a distorted image with brightness of 11 steps is displayed. It goes without saying that it is possible to display a distorted image of the brightness of ℃.

Furthermore, as a clock pulse generation circuit, in addition to a locked oscillator, a combination of an oscillator that constantly oscillates and a gate circuit that prevents this oscillation output from being transmitted during the blanking period can also be used. Any method may be selected and used as long as it does not generate a clock pulse during the blanking period.

As described above, according to the apparatus of the present invention, it is possible to arbitrarily and easily change the position of the distorted image of steps of different brightness, and moreover, it is possible to prevent the brightness steps from jumping during the blanking period. There is no better staircase wave television signal that can be emitted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a staircase wave television signal generator according to an embodiment of the present invention, and FIG. 2A is a block diagram. B, C, D, E, F, G, and H are waveform diagrams for explaining the operation of the same device, Fig. 3 is a detailed block diagram of the reset circuit used in the same device, and Fig. 4 is a detailed block diagram of the reset circuit used in the same device. FIG. 4 is a front view showing a display mode when used. 1... Synchronous signal generation circuit, 2... Locked oscillator, 3... Counter, 4...
...Reset circuit, 10...D-A converter.

Claims (1)

[Claims] 1. A clock pulse generation circuit such as a locked oscillator that stops generating clock pulses during the blanking period, a counter that counts these clock pulses and generates a binary output for generating a staircase wave, and this counter is operated at an IH cycle. a reset circuit that generates a position-variable reset pulse that can be reset at any position during the IH period, and a D-A converter that converts the binary output into a staircase wave television signal by D-A converting the binary output. A staircase wave television signal generator comprising: