JPH02277123A - Computer - Google Patents

Abstract

PURPOSE:To perform the display with a display means where a power supply is applied by detecting the application of the power supply of a connected display means with a detecting means and switching the display to the display means where the application of the power supply is detected. CONSTITUTION:It is supposed that the power supply of a personal computer is not applied, i.e., that the power supply of a CRT display 18 is not applied although a CRT control circuit 10 is working. Under such conditions, a logical gate 2c is turned off by a signal, the inverse of CRTCn even when the device 18 is normally connected and a signal, the inverse of CRTPw is kept at an H level and the display is carried out on a plasma device 17. When the power supply of the device 18 is applied under such conditions, the gate 2c is turned on and an output signal, the inverse of CRTPw is set at an L level. Thus a display enable state is secured and the display device is immediately switched to the device 18 with the circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a computer to which a plurality of display means can be connected.

(Prior Art) A conventional computer, for example, a laptop personal computer, uses a built-in plasma display as a display device.
In addition to having a flat display such as a liquid crystal display, it is known that an optional external display device such as a CRT monitor can be connected. Among these computers, those that cannot display the built-in display device and the external display device at the same time even if they are connected at the same time, can now be switched to one of the two using a dip switch or key operation. was.

[Problems to be Solved by the Invention] However, the settings of the dip switch may be inaccurate depending on whether a CRT is connected as an external display device, whether the CRT is plugged in, etc.

Also, if the display surface is carelessly switched using a key operation when the CRT is not in a displayable state,
The problem has been solved that the display is no longer displayed anywhere, giving the illusion that the device is malfunctioning, which is extremely troublesome for general users.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a computer that can display information on a display means when the power is turned on.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a computer to which a plurality of display means can be connected, a detection means for detecting whether the power of the connected display means is turned off, and The present invention is characterized by comprising a switching means for switching the display to the display means for which power-on has been detected by the detection means.

[Function] In the present invention, the detecting means detects that the power source of the connected display means is disconnected, and the switching means switches the display to the display means for which the detecting means detects that the power source is disconnected.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the invention. This is an example of a personal computer.

In FIG. 1, 1 is a power supply circuit, 2 is a CPIJ control circuit as a detection means, 3 is a main memory circuit, and 4 is a BIOS ([
1 asic ilo systems) storage circuit, 5 as DMA (Direct Memory Access)
The IJ control circuit 6 is a system clock circuit. 7 is C
This is a system information storage circuit using a low power consumption type memory such as MO5RAM, which stores system parameters and the like.

The system clock circuit 6 and the system information storage circuit 7 are
Backed up by a lithium battery.

9 is a plasma control circuit, 10 is a CRT control circuit, and CP
A switching means is constituted together with the U control circuit 2.

11 is floppy disk drive (FDD): p+J
control circuit, 12 is a keyboard control circuit. Reference numeral 15 denotes a peripheral device control circuit, which includes a peripheral device control circuit 13.
14 etc. 16 is system lotus, 1
7 is a plasma device with a built-in personal computer, 18
19 is a CRT device, 19 is an FD device, 20 is a keyboard device, and 21 is various peripheral devices.

In FIG. 2, 10.18 indicates the same part as in FIG. 22 is a connection cable that connects the CRT control circuit 1 and the CRT device 2; The connection cables 3a, 3b, and 3c respectively receive an R (ned) signal and a G signal as video signals.
A (Green) signal and a B (Blue) signal are supplied, and a vertical synchronization signal Usyn and a horizontal synchronization signal tlsyn are supplied as synchronization signals to the connection cables 3d and 3e. The connection cable 3f carries a CRT signal indicating that the CRT device 18 is powered on and ready for display.
Pw is supplied to the connection cable 3g with a signal CRTCn indicating that the CRT control circuit lO and the CRT device 18 are normally connected by the connection cable 3g, and the connection cable 3h is supplied with a signal CRTCn that indicates that the CRT control circuit lO and the CRT device 18 are connected normally by the connection cable 3g. A power supply Vcc is supplied to the detection circuit section 2b. The connection cable 31 is a GND line.

R is the pull-up resistor for the various logic buffers, la
, lb are input buffers for various signal lines, and 2a is an output buffer. 2c is a logic gate that operates with power supplied from the power supply section of the CUT device.

Next, a control procedure by the cr'u control circuit 2 will be explained.

It is assumed that the personal computer is not powered on. In other words, it is assumed that the CRT control circuit IO is operating, but the CRT device 18 is not powered on. In this state, even if the CIIT device I8 is normally connected, the logic gate 2C is turned off by the signal CIITCn.
The signal CRTPw is FF, and the level of the signal CRTPw is 'H°, and a display is performed on the plasma device 17.

In this state, when the power of the Cr11' device 18 is turned on, the logic gate 2c is turned ON and the level of the output signal CIITPw of the output buffer 2a is set to °L°, and the display is enabled. Immediately CR
Switch to T device 18.

In this embodiment, an example has been described in which the main body is powered on before the display device is powered on, but at the time the main body is powered on, the level of the signal CRTP* signal is already at °L.
If it is, it may be displayed on the CRT device 18.

Conversely, while displaying on the CRT device 18, the CRT device 1
When the power source 8 is turned off, the level of the signal IITPII+ becomes 11', so this signal may be detected and the plasma device 17 automatically switched to the plasma device 17.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a computer according to an embodiment of the present invention, and FIG. 2 is a CRT control circuit lO and CRT device 18 shown in the first diagram.
FIG. 3 is a diagram showing signals etc. supplied to a connection cable connecting the. 3... Connection cable, 10... CRT 1 circuit, 18... CRT device, CIITP+v... Signals supplied to connection cable 3f, la, lb, 2a, 2c - logic gate. [Effects of the Invention] As explained above, according to the present invention, since it is configured as described above, there is an effect that display can be performed on the display means that is powered on.

Claims (1)

[Claims] In a computer to which a plurality of display means can be connected, there is provided a detection means for detecting power-on of the connected display means, and switching for switching the display to the display means whose power-on is detected by the detection means. A computer characterized by comprising means.