JPS64706B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a CRT that connects a personal computer to a television receiver and simultaneously displays data images from the personal computer by superimposing them on a CRT screen with television broadcast images. This invention relates to a display device.

Recently, personal computers have come to be used in ordinary households. Attempts are now being made to connect a home color television receiver as a CRT display device to a personal computer and display data from the personal computer on the color television receiver.

<Prior art> Figure 1 shows a general technology in which a personal computer is connected to a color television receiver.
1 is a schematic diagram of a CRT display device. First, referring to FIG. 1, when data entered from the keyboard 1 is input into the personal computer 2,
R, G, and B signals for displaying the data on the color television receiver 3 are applied to a signal mixing circuit 32 included in the television circuit 31.
Then, the R, G, and B signals are applied to the CRT 33 via the signal mixing circuit 32, and characters or graphs are displayed.

By configuring the CRT display device in this manner, data images such as various characters and graphs can be displayed using the color television receiver 3 as a monitor. Furthermore, recently, CRTs, which display data from personal computers superimposed on color television broadcasting screens, have become popular.
A display device has been devised.

<Problem> By the way, with such a CRT display device, television images (not only broadcast images)
Since data images from a personal computer are superimposed and displayed on images played back by a VTR or video disk player, etc., depending on the content of the television image, for example, characters or graphs may be included in news programs or educational programs. In such cases, the user may confuse the data image with the data from the personal computer.
There was a drawback that it was difficult to immediately identify which image it was.

<Purpose> The present invention has been made in view of the above points, and is intended to prevent the user from confusing the two images in a device that can simultaneously project and display a television image and a data image from a personal computer on a CRT screen. The purpose of the present invention is to provide a CRT display device in which there is no risk of such occurrence.

In particular, in the present invention, by adding shading to data images from a personal computer, the user can easily identify which images they are.
The object of the present invention is to provide a CRT display device, and furthermore, to provide a CRT display device in which this shadow can be easily erased when desired.

<Example> The present invention will be described below with reference to the drawings. First, the second
The basic configuration diagram on which the present invention is based is shown in the figure, and the principle of operation for adding shading to a data image from a personal computer will be explained based on this diagram.

In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals. Here, 1 is an OR gate for detecting the presence or absence of data output from the personal computer 2, that is, R, G, B output, and 5 is a one-shot pulse that generates a one-shot pulse whose pulse width can be varied by a variable resistor 8. It is a pulse generation circuit, 6 is an amplifier, and 7 is a transistor.
In the CRT display device constructed from the above, a character image R as shown in FIG. 3A is projected on the CRT screen as data output from the personal computer 2;
The operation when the G and B outputs are derived will be explained.

In this case, at least one of the R, G, and B outputs of the personal computer 2 is derived as an "H" output on the line that crosses the character 〓〓 on the CRT screen, for example, the A-A' line.
A rectangular wave pulse as shown in FIG. 3B is derived from the OR gate 4 and supplied to the one shot pulse generating circuit 5. At this time, the generating circuit 5 is triggered by the falling edge of this pulse, and as shown in FIG.
A positive one-shot pulse having a constant pulse width T ₀ as shown in FIG. 1 is output and supplied to the base of the transistor 7. The transistor 7 is turned on only during this pulse period, and an inverted pulse signal of negative polarity is derived from the collector as shown in FIG. 3d, which is supplied as a shadow signal to the signal mixing circuit 32 in the television circuit 31. Here, it is superimposed on the television image signal, particularly the luminance (Y) signal. As a result, the rear edge of the character image from the personal computer 2 is shaded in black on the screen of the CRT 33, as shown in FIG. Such shading cannot be applied.

In addition, the width of the shadow projected on the screen of the above display device can be varied by changing the value of the output pulse width T ₀ of the one-shot pulse generation circuit 5 using a pulse width adjustment variable resistor 8 attached to the one-shot pulse generation circuit 5. It can be set arbitrarily by doing this. However, in this case, if the pulse width T ₀ is made so wide that the shadow of the character on the screen overlaps a part of the adjacent character image, or if the horizontal spacing between the character itself or adjacent characters is narrow, even if the one-shot pulse Even when a positive one-shot pulse is being output from the generating circuit 5, the output of the OR gate 4 is at the "H" level due to the subsequent character output derived from the personal computer 2, and the output of the amplifier 6 is also at the "H" level. Therefore, at this time, the transistor 7 is in a cut-off state, and therefore no shadow signal is derived from the collector. On such a result screen, the shadow of one character will not erode part of the adjacent character.

By the way, in the above-mentioned CRT display device, the width of the shadow added to the data image of the personal computer 2 can be arbitrarily adjusted by the variable resistor 8 for adjusting the pulse width of the one-shot pulse generation circuit 5. , On the other hand, the above variable resistor 8
Even when the aperture is narrowed down, the width T ₀ of the pulse generated by the one-shot pulse generation circuit 5 is about 50 nsec, so in this case it was not possible to completely erase the shadows in the data image.

Therefore, the present invention has been improved in consideration of these points, and especially when the user narrows down the pulse width adjustment variable resistor 8 at a desired time, it is possible to completely remove the shadows attached to the data image. The purpose is to provide a CRT display device that can

FIG. 4 shows one embodiment of the present invention,
Here, in particular, the transistor 9 and the resistors 10, 1
A reset circuit 13 consisting of 1 and 12 is added, and the circuit 13 detects the narrowing state of the variable resistor 8 for adjusting the pulse width, and when the variable resistor 8 is narrowed to a predetermined value or more, the circuit 13 outputs a one-shot pulse generating circuit. 5 to stop the operation of the pulse generating circuit 13.

That is, since the maximum value of the pulse width adjusting variable resistor 8 attached to the one-shot pulse generating circuit 5 is sufficiently smaller than the value of the resistors 10 and 11 in the reset circuit 13, this one-shot pulse generating circuit The pulse width of the one shot pulse generated at 5 is mainly determined by the product of variable resistor 8 and capacitor 14. In a steady state, that is, when the variable resistor 8 has an appropriate value, the transistor 9 is in an on state, and the one-shot pulse generating circuit 5 operates when a data image from the personal computer 2 is detected, similar to the circuit operation shown in FIG. A one shot pulse is generated according to the value of variable resistor 8,
This causes the trailing edge of the data image to be shaded on the CRT screen.

However, when the user does not wish to add such shading, when the pulse width adjustment variable resistor 8 is narrowed down to a predetermined value or more, the transistor 9 is cut off and the collector becomes ground potential, so the one-shot The yacht pulse generation circuit 5 is always in a reset state and the pulse generation operation is stopped. Therefore, in this case, even when the data output of the personal computer 2 is detected by the OR gate 4, no one shot pulse is generated from the one shot pulse generation circuit 5, and therefore the transistor 7 remains cut off and the signal is mixed. No shadow signal is supplied to circuit 32. In this way, when the user narrows down the pulse width adjustment variable resistor 8 to a predetermined value or more, the shading on the CRT screen, especially the data image of the personal computer, is completely removed, and in this case, the personal computer data image on the CRT screen is completely removed. An image in which the data image from the computer and the television image are simply superimposed is simultaneously displayed.

In the above embodiment, a case was described in which black shading is applied to the color characters from a color television receiver and a personal computer, but it is of course possible to apply color shading as appropriate, and black and white television receivers may also be used. This can also be carried out when the computer is connected to a personal computer.

<Effects> As described above, according to the present invention, a personal computer is connected to a television receiver, and a CRT
In a CRT display device that can simultaneously project and display data images from a personal computer overlaid with a television image on the screen, the data images from the personal computer are particularly shaded, making it easier for users to see the television in the background. The digital image and this data image can be immediately distinguished, so even if characters or data are displayed on the screen in a news program or the like broadcast on television, there will be no confusion.

Furthermore, according to the present invention, it is also possible to completely remove shadows added to data images as desired by the user.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a CRT display device in which a personal computer is connected to a color television receiver, Fig. 2 is a basic block diagram on which the present invention is based, and Fig. 3 is a diagram for explaining the operation of Fig. 3.
Example of CRT screen and signal waveform diagram, 4th
The figure is a block diagram of one embodiment of the invention. 2...Personal computer, 3...Color television receiver, 32...Signal mixing circuit, 3
3...CRT, 4...OR gate for data output detection, 5...One shot pulse generation circuit, 8...
Variable resistor for pulse width adjustment, 13...Reset circuit.

Claims (1)

[Claims] 1. Detects the presence or absence of data output from the personal computer in a CRT display device that connects a personal computer to a television receiver and can simultaneously project and display data images from the personal computer by superimposing them on the CRT screen with the television image. a one-shot pulse generation circuit that is driven based on the detection output of the circuit and generates a one-shot pulse with a variable pulse width; a mixing circuit that mixes the data output with a television image signal; and a reset circuit that stops the operation of the one-shot pulse generation circuit when the pulse width of the one-shot pulse generated in the one-shot pulse generation circuit is narrowed to a predetermined value or more. It is equipped with
A CRT display device characterized in that a data image on a CRT screen can be shaded arbitrarily.