JPH0113484Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Field of application This invention is a method for switching between a video signal such as a normal television signal or a VTR playback signal and a monitor signal consisting of R, G, B primary color signals, etc. The present invention relates to an image receiving device such as a color television receiver or a monitor television receiver that selectively displays images.

(b) Prior Art In FIG. 1, when displaying an image of a video signal such as a normal color television signal or a VTR playback signal, the switches SW ₁ to _{SW 4} are set to the lower side. The video signal applied to terminal 1 is processed by video processing circuit 2 through switch SW ₄ , and its color demodulation outputs R-Y, G-Y, B-Y are sent to switch SW 4.
The signal is applied to a cathode ray tube (hereinafter referred to as "CRT") drive circuit ₃ through SW ₁ , SW ₂ , and SW 3 . The brightness signal Y is directly given to the CRT drive circuit 3.
In the CRT drive circuit 3, the above R-Y, G-Y, B
- is combined with the Y signal to form the primary color signal. At this time, a synchronizing signal in the video signal is applied to the deflection circuit 4, and the deflection circuit 4 applies a deflection current to the deflection coil 6 mounted on the CRT 5.

Next, when displaying the image of the monitor signal, the switches SW ₁ to _{SW 4} are set to the upper side. terminal 7,
A monitor signal consisting of R, G, B signals, a synchronization signal, etc. is applied to 8, 9, 10, and 11. The R, G, B signals are supplied from the R, G, B processing circuit 12 to the CRT drive circuit 3 through switches SW ₁ , SW ₂ , SW ₃ , and the synchronization signal is supplied from the R, G, B processing circuit 12 to the switch SW 1 , SW 2 , SW 3 . ₄ and video processing circuit 2
is applied to the deflection circuit 4 through.

By the way, if we consider the image in the horizontal direction, in the waveform in Figure 2 A, the period _W1 is the valid image information part, but in reality it is due to high pressure fluctuations.
In order to capture the image expansion/contraction and high-pressure regulation range on the CTR 5, the W ₂ period in Figure 2 A is displayed on the CRT 5. This means that 85% of all images are displayed.

However, in the monitor signal, as shown in Figure 2 (b), the starting point of the image relative to the horizontal synchronizing pulse HP is different, and in the case of text information, only 85% of the effective image information is displayed as shown in Figure 2 (a). Otherwise, the first character will be missing. That is, when the monitor signal shown in FIG. 2B is displayed on a television receiver set to display 85% of the signal as shown in FIG. 2A, the _W4 period will not be displayed on the CRT 5.

The difference in the synchronization signal period and image information period between the normal video signal and the monitor signal, as shown in Figure 2 A and B, is because the monitor signal is formed using a computer used in word processors, etc. Occurs when

In other words, the manufacturer's design of these types of word processors and computers for personal computers determines the insertion position of image information to match the equipment, so such computers can be used to receive monitor signals from television. Discrepancies in the horizontal position of the image become a problem when displaying images on a computer or when using a computer purchased from another manufacturer to create a receiver that can display both monitor and video signals.

(c) Purpose In view of the above, the present invention aims to realize a horizontal position of an image suitable for both video signal and monitor signal display.

(d) Structure The present invention enables optimal display of images based on the video signal and monitor signal by switching the circuit elements of the image horizontal position determining means in accordance with the switch for switching between the video signal and the monitor signal.

(E) Embodiment In FIG. 3, in addition to the switches SW ₁ to _{SW 4} similar to those in FIG. 1, a fifth switch SW ₅ is added.
is provided to operate in conjunction with the switches _SW1 to _SW4 , and the common point a of the fifth switch _SW5 is connected to the AFC sawtooth wave input terminal 14 of the deflection system IC ₁₃ via a resistor R2, Contact b on the video signal side is in the upright position, and contact e on the monitor side is connected to adjustment volume _VR1 . This adjustment volume VR ₁ is connected in series with a resistor R ₃ between the 12V power supply terminal 15 and ground. The elements connected to the contact e and the common point a constitute a part of the deflection system circuit. The IC 13 has an AFC circuit 18 that operates only during the horizontal synchronization pulse period based on the sawtooth wave voltage 17 input to the input terminal 14 and the horizontal synchronization pulse HP separately applied to the input terminal 16. Controls the frequency of the oscillation circuit 19.
The flyback pulse FP applied to the terminal 20 is converted into a waveform by the resistor R ₁ and the capacitors C ₁ and C ₂ , and a sawtooth wave voltage is generated at the point f. _C3 is a coupling capacitor. First, a case will be explained in which the switch SW ₅ is set to the contact point b. Now, flyback pulse FP, image information S and horizontal synchronization pulse HP
4 have the temporal positional relationships shown in FIG. 4A, B, and C, the waveform when the flyback pulse FP is converted into a sawtooth wave voltage becomes 17 in FIG. 4D. In the AFC circuit 18, the time t=t ₁ when this sawtooth wave voltage 17 rises at AC=OV
[Figure 4 D] and the generation time t of the horizontal synchronizing pulse HP
= t ₂ [Figure 4 C], generates AFC output to synchronize the flyback pulse FP and the horizontal synchronization pulse HP, and activates the horizontal oscillation circuit 1.
It controls 9. In this case, the AC=0 level means that the horizontal center of the image based on the video signal is the CRT.
It is set to be in the center of 5. Note that a variable resistor may be inserted between the contact point b and the ground, and the variable resistor may be adjusted so that the image is centered.

Next, during monitoring with the fifth switch SW ₅ set to the contact e side, the potential at point f, that is, the AC=0 level of the sawtooth wave voltage 17 is raised by coupling the volume VR ₁ . This raised AC=0 level is the second level.
When considered in accordance with the AC=0 level in the figure, it is equivalent to the sawtooth wave voltage 17 becoming as shown in 17'. That is, due to the coupling of the volume VR ₁ , the time at which the sawtooth wave voltage cuts off the AC=0 level is delayed from t=t ₁ to t=t ₃ .

In this case, the AFC circuit 18 performs a comparison between t ₂ and t ₃ , so that control is performed so that the phase of the flyback pulse FP advances. The progress of the flyback pulse in this way is the flyback pulse.
This means that the distance between the FP and the image information portion S is widened, so the image displayed on the CRT 5 moves to the right.

Therefore, in the case of the monitor signal shown in FIG. 2B, the entire image information period _W3 is displayed on the CRT 5.

The horizontal position of the image displayed on the CRT 5 can be adjusted arbitrarily by changing the volume VR ₁ , but this is because in the case of monitor signals, the image period may be later than the example shown in Figure 2. In that case, the AC=0 level may be lowered to move the image to the left.

(F) Effect According to the present invention, the content of the image (mere image,
Even if the image information is different (such as character images) or the temporal position of the image information is shifted, the circuit elements of the image horizontal position determining means can be switched in accordance with the video signal and monitor signal changeover switch. , so each image can be viewed as an image at a preset optimal position. Also,
The position of the image can be corrected by using an adjustable element such as a volume as the element.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram schematically showing a conventional image receiving apparatus, and FIG. 2 is an explanatory diagram thereof. FIG. 3 is a circuit diagram of a main part of an image receiving apparatus embodying the present invention, and FIG. 4 is an explanatory waveform diagram thereof. SW ₁ ~ _{SW 4} ...Switch, SW ₅ ...Switch,
VR ₁ ...Volume.

Claims (1)

[Claims for Utility Model Registration] Two different types of image information are selectively displayed by switching between them using a switch means, and a sawtooth wave obtained by converting the waveform of a flyback pulse using a waveform shaping means and a horizontal synchronizing pulse. AFC which compares and controls the frequency of the horizontal oscillation circuit using this comparison output
In the image receiving device including a circuit, means is provided for switching a circuit element of the waveform shaping means that determines the phase of the sawtooth wave in conjunction with the switching means, and the horizontal position of the image is adjusted according to two different types of image information. An image receiving device characterized by switching between.