JPH06161367A - Horizontal centering circuit - Google Patents

Abstract

(57) [Summary] [Purpose] When the signals from a personal computer or the like are switched to different types, control is performed so that the images displayed on the monitor screen are displayed without being biased to the left or right. A signal of an all-white image is input during an image period of horizontal scanning, a video signal is separated by a video signal separation circuit 3, and a differentiation circuit 4 differentiates it to generate a rising signal and a falling signal of the image. . Waveform shaping circuit 5 for rising signal
Waveform shaping is performed by the integrating circuit 6 and is input to the amplitude coincidence detecting circuit 9. The falling signal is waveform shaped by the waveform shaping circuit 7, integrated by the integrating circuit 8 and input to the amplitude coincidence detecting circuit. The position where the amplitude of the signal from the integrator circuit 6 coincides is detected and input to the phase comparator circuit 11. The zero-cross detection circuit 10 detects the zero-cross position from the output signal of the horizontal deflection circuit 2, compares it with the phase comparison circuit, outputs the signal of the phase difference between the two signals, and the phase control circuit 12 outputs the phase of the horizontal deflection circuit. To control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal centering circuit for an image on a monitor or the like, and to adjusting the phase so that the horizontal center of the image becomes the center of the raster.

[0002]

2. Description of the Related Art In a monitor or the like for switching and displaying video signals of different standards output from a personal computer (hereinafter abbreviated as personal computer) or the like, the position (phase) of the image scanning period with respect to the entire horizontal scanning period is a signal. There is a difference depending on the source, and in such a case, the position of the image displayed on the screen of the monitor or the like is biased to the left or the right.
For this reason, for example, a signal for phase adjustment for each type of signal is stored in advance in a monitor or the like, the type of signal is identified at the time of signal input, the adjustment signal corresponding to the type of signal is taken out, and the horizontal deflection circuit Is controlled so that the center of the image in the horizontal direction is the center of a cathode ray picture tube (hereinafter abbreviated as a picture tube).

[0003]

In the above case, there is no problem as long as the type of the input signal is of the standard stored in the monitor, but when the type of the unstored standard is input. Cannot handle. In view of such a point, the present invention allows a personal computer to output a video signal of a white image during the entire image period of horizontal scanning by a required operation, detect the center position of the image period from this video signal, and detect this position. To detect the phase difference between the center position of the raster and the center position of the raster, and control the phase of the signal processed by the horizontal deflection circuit according to this difference so that the center of the image becomes the center of the picture tube. It is in.

[0004]

In order to solve the above-mentioned problems, the present invention provides a horizontal deflection circuit for horizontally deflecting a cathode ray picture tube based on a horizontal synchronizing signal, in which a whole image period of horizontal scanning is a white image. An input section for designating a signal input, a video signal separation circuit for separating a video signal from a signal input based on the designation, and a signal and a video at the time of rising of the video signal by differentiating the signal from the video signal separation circuit. A differentiating circuit that outputs a signal when the signal falls, a first integrating circuit that performs integration based on the signal when rising, a second integrating circuit that performs integration based on the signal when falling, and the first An amplitude coincidence detection circuit that detects a coincidence point of amplitude by a signal from the integrator circuit and a signal from the second integrator circuit, and a zero cross detector that detects a zero cross of the output signal of the horizontal deflection circuit. A cross detection circuit and a phase comparison circuit that outputs a phase difference signal by comparing the phases of the signals from the amplitude coincidence detection circuit and the signal from the zero cross detection circuit, and outputs the horizontal signal based on the signal from the phase comparison circuit. A horizontal centering circuit configured with a phase control circuit for controlling the phase of a deflection circuit is provided.

[0005]

With the above construction, in the horizontal centering circuit according to the present invention, the video signal is separated from the white image signal during the entire horizontal scanning image period output from the personal computer or the like, and this video signal is differentiated. Amplitude coincidence detection of a first signal integrated based on the rising signal and a second signal integrated based on the falling signal by outputting signals at the rising and falling edges of the video signal, respectively It is input to the circuit, the phase of the first signal at the position where the amplitudes match is detected, this phase is compared with the phase at the zero cross position detected from the output signal of the horizontal deflection circuit, and based on the phase difference, the horizontal deflection circuit Controls the phase of the processed signal.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a horizontal centering circuit according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of essential parts of an embodiment of a horizontal centering circuit according to the present invention. In the figure, reference numeral 1 denotes an HD separation circuit which separates a horizontal synchronizing signal by a signal input from a personal computer or the like. Two
Is a horizontal deflection circuit, which generates a horizontal deflection signal based on the signal from the HD separation circuit 1 and horizontally deflects the picture tube. Three
Is a video signal separation circuit, which extracts the video signal by slicing the sync signal portion from the video signal of the white image for the entire image period of the horizontal scanning which is input by the required designation. A differentiating circuit 4 differentiates the video signal from the video signal separating circuit 3 and outputs the signal when the video signal rises and falls. Reference numeral 5 denotes a waveform shaping circuit, which shapes the signal from the differentiating circuit 4 at the time of rising. Reference numeral 6 denotes an integrating circuit, which performs integration based on the signal from the waveform shaping circuit 5. Reference numeral 7 denotes a waveform shaping circuit, which shapes the signal from the differentiating circuit 4 at the time of falling. Reference numeral 8 denotes an integrating circuit, which performs integration based on the signal from the waveform shaping circuit 7. 9 is an amplitude coincidence detection circuit,
In the signal from the integrator circuit 6, the phase at the position corresponding to the amplitude of the signal from the integrator circuit 8 is detected. Reference numeral 10 is a zero-cross detection circuit, which detects the phase of the output signal of the horizontal deflection circuit 2 at the zero-cross position. Reference numeral 11 denotes a phase comparison circuit, which compares the signal from the amplitude coincidence detection circuit 9 and the signal from the zero-cross detection circuit 10 and outputs a phase difference signal. 12
Is a phase control circuit that controls the phase of the signal processed by the horizontal deflection circuit 2 based on the signal from the phase comparison circuit 11.

Next, the operation of the horizontal centering circuit according to the present invention will be described with reference to the waveform diagram of FIG. A signal output from a personal computer or the like is input to the HD separation circuit 1, the horizontal synchronizing signal is separated and input to the horizontal deflection circuit 2 to generate a horizontal deflection signal, and the picture tube is horizontally deflected.

By a required designation operation, a signal is sent to a personal computer or the like which is a signal source to output a composite video signal 21 of a white image for the entire image period of horizontal scanning. From this composite video signal 21, the video signal separation circuit 3 slices and removes the synchronizing signal, and the video signal 22 is taken out and differentiated by the differentiating circuit 4. By this differentiation, the rising position of the video signal (white image) 23
The positive pulse 24 is output at, and the negative pulse 26 is output at the falling position 25. The positive pulse 24 is input to the waveform shaping circuit 5, shaped into a waveform, and input to the integrating circuit 6 to generate an integrated waveform 27 which becomes a zero level at the falling position 25, and the integrated waveform 27 is detected by the amplitude coincidence detection circuit 9 To enter. Further, the negative pulse 26 is input to the waveform shaping circuit 7, shaped into a waveform, and input to the integration circuit 8 to generate an integrated waveform 28 which becomes a zero level in the same period as the integrated waveform 27, and the amplitude coincidence detection circuit Enter in 9. In the amplitude coincidence detection circuit 9, the integrated waveform 27
At, the phase at the position 29 where the amplitude i of the integrated waveform 27 and the amplitude b of the integrated waveform 28 have the same amplitude is detected and input to the phase comparison circuit 11. The position 29 in the integrated waveform 27 indicates the horizontal center position of the image.

On the other hand, the zero cross detection circuit 10 detects the phase of the zero cross position 31 from the output signal (current waveform of the horizontal deflection coil, etc.) 30 of the horizontal deflection circuit 2 and inputs it to the phase comparison circuit 11. The zero cross position 31 is the horizontal center position of the raster of the picture tube. Phase comparison circuit
At 11, the phase of the signal from the amplitude coincidence detection circuit 9 and the phase of the signal from the zero cross detection circuit 10 are compared and a signal corresponding to the phase difference is output. This signal is input to the phase control circuit 12, and the phase control circuit 12 controls the phase by delaying the signal of the horizontal deflection circuit 2. As a result, the horizontal position of the image displayed on the picture tube is controlled to match the center position of the raster.

[0010]

As described above, according to the horizontal centering circuit of the present invention, the horizontal center position of the image is detected by detecting the horizontal center position of the image from the video signal output from the personal computer or the like by a required designation operation. Phase adjustment is performed so that the center position of the direction matches this position.
An image from a personal computer or the like is displayed in the center on the left and right of the monitor screen regardless of the type of signal. As described above, since it is not necessary to store the image position control data in advance for each type of signal, it is possible to immediately respond even when a signal of a type that is not currently used is input.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts of an embodiment of a horizontal centering circuit according to the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the horizontal centering circuit according to the present invention.

[Explanation of symbols]

 1 HD (horizontal synchronization signal) separation circuit 2 Horizontal deflection circuit 3 Video signal separation circuit 4 Differentiation circuit 5 Waveform shaping circuit 6 Integrator circuit 7 Waveform shaping circuit 8 Integrator circuit 9 Amplitude coincidence detection circuit 10 Zero cross detection circuit 11 Phase comparison circuit 12 Phase Control circuit

Claims (1)

[Claims] 1. A horizontal deflection circuit for horizontally deflecting a cathode ray tube according to a horizontal synchronizing signal, and an input section for designating a video signal input of a white image for the entire image period of horizontal scanning,
A video signal separation circuit that separates a video signal from an input signal based on the designation, and a signal that is differentiated from the video signal separation circuit and outputs a signal when the video signal rises and a signal when the video signal falls. Differentiating circuit, a first integrating circuit that performs integration based on the rising signal, a second integrating circuit that performs integration based on the falling signal, and a signal from the first integrating circuit and a second integrating circuit Amplitude coincidence detection circuit that detects the coincidence point of the amplitude with the signal and a zero cross detection circuit that detects the zero cross of the output signal of the horizontal deflection circuit, and the signal and the zero cross detection from the amplitude coincidence detection circuit A phase comparison circuit that compares the phases of the signals from the circuits and outputs a signal with a phase difference, and determines the phase of the horizontal deflection circuit based on the signals from the phase comparison circuit. Horizontal centering circuit which is constituted by a Gosuru phase control circuit.