JPH0441670Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field> The invention relates to a CRT display with television function.
This invention relates to a CRT display with television function that is equipped with a superimpose function that supports digital RGB.

<Prior art> This type of CRT display with a television function that supports new media is mainly intended for use as a display for a personal computer, and in this case, it is designed to also have a superimpose function. is normal. This superimposition uses the Ys signal (RGB high-speed switching switch control signal), which is a control signal for switching the RGB signal to an internal signal (television RGB signal) and an external signal (external RGB signal), to control the Ys circuit. This is done by switching the RGB signal portion of the video source to an external RGB signal from a personal computer or the like. This Ys
Regarding signals, analog RGB and digital RGB
Analog Ys signal/digital
It is necessary to switch the Ys signal.

In such a CRT display with a television function, when switching to television mode while external input from a personal computer is being applied, the Ys circuit is prevented from operating by eliminating the influence of the Ys signal. must be done. It is extremely troublesome to provide a changeover switch for disabling the Ys circuit in response to switching to the television mode and to operate the switch every time the television mode is switched.

<Purpose of the invention> The present invention was devised in view of the above-mentioned points. When switching to television mode while receiving external input from a personal computer, etc., the Ys signal The purpose is to automatically eliminate the influence and prevent the Ys circuit from operating.

<Configuration of the invention> In order to achieve the above-mentioned object, the present invention uses a CRT display with a television function, which has an analog RGB external input terminal and a digital RGB external input terminal, and is equipped with a superimpose function. an RGB interface circuit that selects and outputs either a television RGB signal or an external RGB signal from the external input terminal based on an RGB high-speed changeover switch control signal), a digital Ys signal generation circuit, and an analog
Ys signal input terminal, a selection switch that is operated to select either analog RGB or digital RGB as the external RGB signal, and a selection switch that is operated to select either analog RGB or digital RGB as the external RGB signal, and a
External input from the corresponding external input terminal of the RGB external input terminal or analog RGB external input terminal
A first selector switch outputs an RGB signal to the RGB interface circuit, and in conjunction with the switching operation of the selection switch, one of the digital Ys signals from the digital Ys signal generation circuit or the analog Ys signal from the analog Ys signal input terminal is connected. a second changeover switch that outputs a corresponding Ys signal to the RGB interface circuit; and a second changeover switch that outputs a Ys signal corresponding to the RGB interface circuit, and is interposed between the selection switch and each of the changeover switches; and a switching element for switching the second changeover switch to the digital Ys signal generation circuit side and outputting the digital Ys signal from the second changeover switch.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The drawing is a block circuit diagram of essential parts of an embodiment of the present invention. The CRT display with television function of this embodiment has a superimpose function. In the figure, 1 is a digital RGB external input terminal to which a digital RGB signal from a personal computer is input, and 2 is an analog RGB external input terminal to which an analog RGB signal from the personal computer is input.
3 is an RGB interface IC, and this RGB
The interface IC 3 selects either the television RGB signal or the external RGB signal from the external input terminals 1 and 2 based on the Ys signal (RGB high-speed changeover switch control signal) and outputs it to a CRT circuit (not shown). This is the so-called Ys circuit. This RGB interface IC 3 selectively outputs the television RGB signal when the Ys signal is at low level, and selectively outputs the external RGB signal when the Ys signal is at high level.

4 is analog Ys signal input terminal, 5 is digital
This is a Ys signal generation circuit. This digital Ys signal generation circuit 5 operates only in superimpose mode, and its output is always at low level in television mode, and always at high level in computer mode. It is configured.

In this embodiment, a selection switch 6 is operated to select either analog RGB input or digital RGB input, and digital RGB external input terminal 1 or analog RGB external A first changeover switch 7 outputs an external RGB signal from a corresponding external input terminal of the input terminals 2 to the RGB interface IC 3, and a first changeover switch 7 outputs an external RGB signal from a corresponding external input terminal of the input terminals 2, and outputs an external RGB signal from the analog Ys signal input terminal 4 in conjunction with the switching operation of the selection switch 6. Analog Ys signal or digital Ys signal generation circuit 5
The corresponding Ys signal of the digital Ys signal from
A second changeover switch 8 that outputs to the RGB interface IC 3 is interposed between the changeover switches 7 and 8 and the selection switch 6, and when in television mode, the selection switch 6 and the changeover switches 7,
8, and switches each switch 7, 8 to the digital RGB external input terminal 1 side and the digital Ys signal generation circuit 5 side, respectively.

The selection switch 6 consists of an individual empty contact 6a, an individual contact 6b connected to the emitter of the switching transistor Q, and a grounded movable contact 6c.When selecting digital RGB input, the individual empty contact 6a is connected to the When selecting analog RGB input, the movable contacts 6c are switched to the individual contacts 6b.

The first and second changeover switches 7 and 8 are both analog switches. The first changeover switch 7 has a first individual contact 7a connected to the digital RGB external input terminal 1, a second individual contact 7b connected to the analog RGB external input terminal 2, and a movable contact 7a connected to the RGB interface IC 3. It includes a contact 7c and a control terminal 7d for switching and controlling the movable contact 7c. The second changeover switch 8 is a digital Ys
A first individual contact 8a connected to the signal generation circuit 5
, the second individual contact 8b connected to the analog Ys signal input terminal 4, and the RGB interface IC 3.
The movable contact 8c connected to the
and a control terminal 8d for switching control.

Control terminals 7d and 8d of each switch 7 and 8
is connected to the collector of the switching transistor Q. When a high-level control signal is applied to the control terminals 7d, 8d of each changeover switch 7, 8, when a low-level control signal is applied to the first individual contact 7a, 8a side, the second individual contact 7b,
The movable contacts 7c and 8c are respectively switched to the 8b side.

A low level discrimination signal is applied to the base of the switching transistor Q from a mode discrimination circuit (not shown) in the television mode, and a high level discrimination signal is applied in the computer mode or superimpose mode. R1 and R2 are bias resistors.

Note that in the figure, each of the R, G, and B signal lines is representatively shown as one signal line.

Next, we installed a television with the above configuration.
The operation of a CRT display will be explained.

First, when the CRT display is in the computer mode or superimpose mode, a high level discrimination signal is applied to the base of the switching transistor Q from a mode discrimination circuit (not shown). At this time, the selection switch 6 becomes operational, and the selection switch 6 allows digital RGB input or analog input.
A high-level or low-level control signal is applied to the control terminals 7d and 8d of the first and second changeover switches 7 and 8 in response to the selection of one of the RGB inputs. When digital RGB input is selected by the selection switch 6, that is, when the movable contact 6c is operated to the individual empty contact 6a side, the movable contact 7 of the first changeover switch 7 is switched in conjunction with the selection operation.
c is a second changeover switch 8 on the first individual contact 7a side.
The movable contacts 8c each move to the first individual contact 8a side, and on the other hand, when analog RGB input is selected, that is, when the movable contact 6c is operated to the individual contact 6b side, The movable contact 7c of the first changeover switch 7 is located on the second individual contact 7b side, and the movable contact 8c of the second changeover switch 8 is connected to the second individual contact 7b side.
are respectively switched to the second individual contact 8b side.

Next, when the CRT display is switched to the television mode, a low level discrimination signal is applied to the base of the switched transistor Q from the mode discrimination circuit. At this time, the switching transistor Q is always turned off regardless of the operation of the selection switch 6. As a result, a high level control signal is given to the control terminals 7d and 8d of the first and second changeover switches 7 and 8, and the movable contact 7c of the first changeover switch 7 becomes the first individual contact. 7a side, the movable contact 8c of the second changeover switch 8 is switched to the first individual contact 8a side. Therefore, in the television mode, the RGB interface IC 3 is not affected by the analog Ys signal applied to the analog input terminal 4, and the digital Ys signal generation circuit 5
A low level output is always given from the RGB interface IC 3, so that the RGB interface IC 3 selectively outputs the television RGB signal.

With this relatively simple circuit configuration, when in television mode, the RGB interface IC3 automatically eliminates the influence of the Ys signal and always selectively outputs only the television RGB signal to the CRT circuit. mode, Ys
It is very convenient to provide a changeover switch or the like to stop the operation of the circuit and operate it every time the television mode is switched.

<Effects of the invention> As described above, according to the invention, the influence of the Ys signal can be automatically eliminated during television mode using a relatively simple circuit configuration, which is very convenient. .

[Brief explanation of drawings]

The drawing is a block circuit diagram of essential parts of an embodiment of the present invention. 1... Digital RGB external input terminal, 2... Analog RGB external input terminal, 3... RGB interface IC, 4... Analog Ys signal input terminal,
5... Digital Ys signal generation circuit, 6... Selection switch, 7, 8... First and second changeover switch, Q
...switching transistor.

Claims (1)

[Scope of claim for utility model registration] Analog RGB external input terminal and digital
In a CRT display with a television function that has an RGB external input terminal and has a superimpose function, the television RGB signal or the external RGB signal from the external input terminal is input based on the Ys signal (RGB high-speed switching switch control signal). an RGB interface circuit that selects and outputs one of the above, a digital Ys signal generation circuit, an analog Ys signal input terminal, and a selection that is switched to select either analog RGB or digital RGB as the external RGB signal. switch, and in conjunction with the switching operation of this selection switch, external input from the corresponding external input terminal of the digital RGB external input terminal or analog RGB external input terminal
a first changeover switch that outputs an RGB signal to the RGB interface circuit; and a first selector switch that outputs an RGB signal to the RGB interface circuit; a second changeover switch that outputs a Ys signal corresponding to the RGB interface circuit to the RGB interface circuit; In addition to cutting off the linkage with the switch, the second changeover switch can also be digitally changed.
A CRT display with a television function, comprising a switching element that switches to the Ys signal generation circuit side and outputs a digital Ys signal from the second changeover switch.