JPH0793690B2 - Vertical shift circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a television receiver, a video projector, and a received image, optionally by software,
The present invention relates to a vertical shift circuit that can move in the vertical direction (vertical direction).

2. Description of the Related Art In recent years, projection type video projectors (hereinafter abbreviated as VPS) among television receivers have begun to attract attention due to the trend toward large screens.

FIG. 3 shows a schematic block diagram of the VPS. In the figure, 1 is a Y / C separation circuit that separates a video signal into a luminance signal and a chrominance signal, 2 is a video amplifier circuit that amplifies the luminance signal Y, 3 is a color demodulation circuit that returns a color signal to an I, Q or color difference signal, 4 is RGB
Matrix circuit for obtaining signals, 5 to 7 are RGB cathode ray tubes (hereinafter abbreviated as CRT), 8 to 10 are lenses for converging light of CRTs 5 to 7, 11 is a sync separation circuit for obtaining a sync signal from a video signal, Reference numeral 12 is a vertical deflection circuit, 13 is a horizontal deflection circuit that generates horizontal deflection and high voltage, and 14 is a screen that displays a projected image.

The operation of the VPS configured as described above will be briefly described below.

The input video signal is input to the Y / C separation circuit 1 and separated into a Y signal representing a luminance component and a C signal representing a color component even in the video signal. The Y signal is supplied to the video signal amplifier circuit 2 and the C signal is supplied to the C signal. For demodulation, the signals are input to the matrix circuit 4 via the color demodulation circuit 3 and converted into RGB primary color signals.
Drive 7 On the other hand, the synchronization relationship is separated from the video signal by the sync separation circuit 11, one of which enters the vertical deflection circuit 12 and the other of which enters the horizontal deflection circuit 13 and outputs a signal for performing horizontal scanning. . The horizontal deflection circuit 13 also includes high voltage generation.

The images projected on the CRTs 5 to 7 are projected on the screen 14 by the lenses 8 to 10 to reproduce a large image.

The VPS as described above can have the following functions.

As shown in FIG. 4, the video signal of the normal NTSC system has an aspect ratio of 4: 3, but the video source has an image such as a movie with a missing top and bottom like a movie.

In such a case, as shown in FIG. 5, for example, the horizontal screen size is made variable while keeping the vertical direction constant, the vertically missing image is expanded vertically to the full extent, and horizontally expanded at the same ratio to obtain the vertically missing image. It is considered to have a function that allows you to enjoy powerful images that do not.

The expansion can be performed by changing the horizontal / vertical deflection current (changing the amplitude).

The problem here is the vertical position of the image. The vertical position of the effective screen is not always constant in a video source with a missing top and bottom, and when it is enlarged to the screen, the video source is offset to the top or bottom.

Therefore, as shown in FIG. 6, the vertical synchronizing signal is delayed by using a monostable multivibrator (hereinafter abbreviated as MM) to change the relative position with respect to the video signal, so that the vertical deviation can be absorbed.

FIG. 7 shows the timing chart.

The first M / M21 is a constant pulse width V1 that determines the lower limit of image movement, the second M / M22 is a variable pulse width V2 that determines the vertical movement amount, and the third M / M23 is a vertical synchronization signal. It is for generating the same pulse width Vo as Vs.

Normally, the vertical synchronization signal is delayed by one field, and the position is adjusted at R2 if necessary, and the vertical position is changed by changing the relative position to the video signal.

Problems to be Solved by the Invention However, in the conventional example, there is a problem that it is not possible to perform remote control from a distant position or to remember a plurality of set positions because adjustment is performed using a volume.

Means for Solving the Problems In order to solve the above problems, the vertical shift circuit of the present invention replaces MM with a presettable counter that counts horizontal pulses, and this preset value can be set by a microcomputer. It is realized by.

With the above-described configuration, the present invention allows the vertical position to be adjusted by the remote controller even if the screen position is shifted from the normal viewing position even when enlarged projection is performed, and the vertical position can be stored. it can.

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

FIG. 1 is a block diagram of a vertical shift circuit according to an embodiment of the present invention.

21 is a counter that outputs a carry C1 when counting a constant value (for example, 255), 22 is a carry C1 that loads a preset value from a microcomputer, and counts a preset value or a maximum count value minus the preset value and carries C2 , 23 is a preset counter
The counter output Qd (1 /
It is a flip-flop that is set in 16) and outputs V0.

The operation of the vertical shift circuit configured as described above will be described below.

The counter 21 is reset by the vertical synchronizing signal Vs, and counts the horizontal pulse 2H (the double horizontal frequency is used so as not to shift in the field). The counter 21 is an 8-bit counter in order to simplify the circuit so that the carry C1 is output at a position about 1/2 of the vertical synchronizing signal Vs.

Data from the microcomputer is input to the counter 22, which is loaded by the carry output C1 of the counter 21. The counter 22 is a counter (9 bits) capable of counting up to 511, and when this loaded data is used as a preset value and counting starts from this value, the carry C
Output 2

A Vo pulse is obtained by resetting the flip-flop 23 with this carry C2 and setting it with Qd of the counter 22.

Where 1Vs is usually 525H (at twice the horizontal frequency),
Since the counter 21 counts 255, if the preset value is set to 270, the output signal Vo can be obtained at the same position as the original vertical synchronizing signal Vs as shown in FIG. If the preset value is made larger than this value, the output signal Vo is delayed with respect to the vertical synchronizing signal Vs as shown in FIG. 2b, the screen is upward, and if it is made smaller, Vo is delayed as shown in FIG. 2C. The screen moves downward with respect to the vertical synchronizing signal Vs.

According to the above configuration, the Vo output is changed to Vs by changing the preset value of the counter 22 by the microcomputer.
Can be set freely, and if this Vo is used as a vertical synchronizing signal, the video screen will move relative to it, and remote control will be possible. Also, if the preset value at that time is stored in memory, the screen position can be remembered.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to easily adjust the vertical position even when an image is projected from the screen when enlarged projection is performed.

Also, since it can be stored in memory, if you keep it in a normal position, you can immediately restore it even if you move it up or down.

[Brief description of drawings]

FIG. 1 is a block diagram of a vertical shift circuit according to an embodiment of the present invention, FIG. 2 is a timing diagram thereof, FIG. 3 is a block diagram of a conventional image display device, and FIG. FIG. 5 is a displayed diagram, FIG. 5 is a diagram showing an enlarged display example of FIG. 4, FIG. 6 is a circuit diagram of a conventional vertical shift circuit, and FIG.
The figure is the timing diagram. 21 …… counter, 22 …… preset counter, 23 …… flip-flop.

Claims (1)

[Claims] 1. A delay circuit using a first counter for determining a lower limit of a moving amount of a vertical display position of a screen by means for demodulating a television signal into a primary color signal and a synchronizing signal, and the obtained vertical synchronizing signal. In order to determine the upper end of the vertical movement amount in response to the output of the delay circuit of No. 2, a second delay circuit with a counter that can change the movement amount by data setting by software is provided. Data is set and placed in the second delay circuit so as to be field-delayed, and when adjustment is required, the data set in the second delay circuit is changed by software to move the projected image up and down. A vertical shift circuit characterized by the above.