JPS6049386A - Brightness adjusting circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a brightness adjustment circuit for a CI-LT display device.

In conventional %C 11+ display manufacturing, the 17 Tough Ace between the monitor control circuit and the monitor is on-field/off 21 box control, and the brightness W@ adjustment is made by the operator directly changing the volume connected to the video lamp inside the monitor. I went there due to circumstances. In addition, in devices where all brightness adjustment is performed by software, a signal line for brightness control is provided separately from the signal line for video signals, and the brightness is switched between normal brightness and high brightness depending on whether the brightness control line is on or off.

Therefore, there is a drawback that fine adjustment of brightness cannot be performed using software.

Therefore, an object of the present invention is to provide a circuit that can perform fine brightness adjustment using software.

According to the present invention, there is a register in which brightness gradation is set by software, a decoder that decodes the output of the register, an open collector circuit connected to each output of the decoder, and each output of the open collector circuit. a resistor connected between the resistor, an open collector circuit for the video signal, a resistor with both ends connected to the output of the open collector circuit for the video signal and the least significant bit of the decoder, and an output sound power supply for the open collector circuit for the video signal. A brightness adjustment circuit is obtained which includes a resistor connected to the display control circuit and a transistor whose emitter is connected to a display control circuit and which receives the output of a video signal as a base current.

Next, the present invention will be described in detail with reference to the drawings showing one embodiment of the present invention.

In FIG. 1, a video signal output from a display control section 28 is connected to an input of an open collector circuit 1. In FIG. 4
The brightness information of the bit is set in register 2, and the output of register 2 is decoded by decoder 3. Open collector circuits 4 to 13 are connected to each output of the decoder 3, and resistors 18 to 26 are connected to each of the circuits. The output of the circuit 4 of the lowest pit of the decoder 3 is connected to the output of the video circuit 1 via a resistor 17. The output of the video circuit 1 is connected to a power supply via a resistor 16 and further connected to an emitter follower circuit 15. The output of the emitter follower circuit 15 is connected to a CRT via a CRT control section 29.

The video signal for display is created by the display control unit 28,
Open collector 1. The signal is transmitted to the CRT control section 29 through the emitter 7 oror 15.17 and displayed on the CRT. The brightness is determined by the input level of the CRT control section 290.

The human power level is determined by the output of the emitter follower circuit 15, 17, that is, the level of the emitter follower's base potential at point A. That is, if the level at point A is low, the display will be dark, and if the level at point A is high, the display will be bright. The level at point A is determined by which circuit of open collector circuits 4 to 13 connected to the output of decoder 3 is turned on. For example, when the circuit 4 is turned on, the point A is connected to the ground through the resistor 17. When circuit 5 is turned on, it is connected to ground through resistors 17 and 18. Compared to when circuit 4 is turned on, when circuit 5 is turned on, the resistance value between point A and ground is higher and the level at point IDA becomes higher. In this embodiment, when the circuit 13 is turned on, the resistance a value is highest and the level at point A becomes high.

The output of decoder 3 can be turned on or off freely by software.
It is selected depending on the contents of register 2 that can be turned off. Since the contents of register 2 can be changed by software and other circuit configurations, the level at point A can be changed by software, and the brightness of the CRT is determined.

Furthermore, if the number of register bits is increased, the set value of the level at point A becomes finer, and the brightness of the CRT display can also be controlled finer.

As described above, the present invention has the effect of easily realizing multi-gradation display by configuring the display brightness to be determined by a register that can be freely set by software. Also, the brightness button 17 operated by the operator. There is also the effect that the degree of freedom in the structural design of CB and T displays is increased by eliminating the - frame.

[Brief explanation of drawings]

The drawing is a circuit diagram showing an embodiment of the present invention in a block diagram.

Claims (1)

[Claims] A register in which a brightness selection command is set, a decoder for decoding the output of the previous signal register, an open collector circuit connected to each output of the previous signal decoder, and a circuit connected between each output of the open collector circuit. an open collector circuit for inputting a video signal; a resistor having both ends connected to the output of the A--pun collector circuit for inputting the video signal and the least significant bit of the decoder; A brightness adjustment device comprising: a resistor that connects the output of the open collector circuit to a power source; and a transistor that inputs the output of the open collector circuit for video signal input as a pace current and has an emitter connected to a display control unit. circuit.