JPS584349B2 - cathode ray tube display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube display device used in information processing devices and the like, and particularly to one that prevents malfunctions during startup.

In cathode ray tube (hereinafter abbreviated as CRT) display devices, C
A high DC voltage is required to accelerate the electron beam in the RT, but this high voltage is applied when the sawtooth horizontal deflection current for horizontal scanning, which is generated under the control of a synchronization signal, rapidly decreases. It is supplied by a scanning and high-voltage generating section, the main part of which is a flyback transformer, which utilizes the resulting back electromotive force.

FIG. 1 shows an example of a conventional CRT display device.

In the figure, 1 is a CRT, 2 is a scanning and high voltage generator, 3 is a display control unit, 4 is an operation enable signal, 5 is a synchronization signal, and 6
7 is a CRT display control signal, 8 is a synchronizing signal generator, 9 is a capacitor for accumulating the DC high voltage, and 10 is a power source.

When the operation enable signal 4 is supplied to the display control unit 3, the display control unit 3 starts operating and transmits the CRT display control signal 7 to the CR.
At the same time, the synchronizing signal generating section 8 coupled to the display control section 3 also starts operating and starts supplying the synchronizing signal 5 to the scanning and high voltage generating section 2.

When the scanning and high voltage generating section 2 receives the synchronization signal 5, it begins to generate a scanning signal (not shown) and a DC high voltage 6 for accelerating the electron beam.The DC high voltage is applied to the CRT 1, and the CRTI is Start displaying.

That is, the CRT display control signal 7 and the electron beam acceleration DC high voltage 6 are generated simultaneously.

The capacitance 9 that accumulates DC high voltage consists of the capacitance between the conductive films coated on the inner and outer surfaces of the funnel of the CRTI, and the stray capacitance between the high voltage part and the ground and other low voltage parts, and its capacitance value is quite large. Although the DC high voltage value generated by the scanning and high voltage generating section 2 is pulsating, the DC high voltage 6 applied to the CRTI is almost constant.

Therefore, a large charging current flows into the capacitor 9 until the DC high voltage 6 applied to the CRT 1 is established and becomes constant.

FIG. 2 is a diagram showing how voltages, currents, signals, etc. of each part change over time when the power supply 10 is turned on and the CRT 1 starts displaying information.

In the figure, 10 is a power supply voltage, 4 is an operational signal, 5 is a synchronization signal, 6 is a direct current high voltage for electron beam acceleration, and 11 is a charging current to the capacitor 9 described above.

At startup, due to the influence of the charging current 11 that flows until the DC high voltage 6 is established, the display control section 3 that is already in operation may malfunction, such as inverting the state storage flip-flop or malfunctioning the display synchronization counter. Sometimes.

In order to prevent such malfunctions, the parts through which the charging current flows and the parts affected by it must be sufficiently shielded, and furthermore, in order to reduce the stray capacitance in the capacitor 9, the mutual arrangement of the parts must be adjusted. However, there are also problems such as the fact that there are major restrictions due to this.

SUMMARY OF THE INVENTION An object of the present invention is to provide a CRT display device that eliminates the problems of the conventional CRT display device and prevents malfunctions caused by the influence of charging current accompanying the establishment of a high DC voltage at startup by simple means. .

In order to achieve the above object, in the present invention, CRT
When starting up the display device, the synchronizing signal generator and the scanning and high-voltage generator are first started, and after the DC high voltage that accelerates the electron beam in the CRT is established, the operation of the display control section is started first. .

FIG. 3 is a diagram showing an embodiment of the present invention.

The symbols are the same as those in FIG. 1, or the synchronization signal generator 8
is not connected to the display control unit 3, and starts operating at the same time as the power supply 10 is turned on, regardless of whether or not the operation enable signal 4 is supplied (that is, whether it is rising or not). , starts scanning and supplying the synchronization principle 5 to the high voltage generator 2.

When the scanning and high voltage generating section 2 starts receiving the synchronization signal 5, it starts generating a scanning signal (deflection current) and at the same time starts generating a pulsed high voltage.

A charging current begins to flow into the capacitor 9 due to this pulsed high voltage, and eventually the capacitor 9 is charged to nearly the maximum value of the pulse, and a DC high voltage 6 for accelerating the electron beam in the CRTI is established.

In some cases, the time required to establish high voltage was approximately 3
It was 0ms.

During this time, since the enable signal 4 is not supplied to the display control section 3, the display control section 3 is not operating.

Therefore, until the DC high voltage 6 is established, the charging current 11 flowing through the capacitor 9 will naturally not cause malfunctions such as malfunction of the display control section 3.

The ready signal 4 is supplied to the display control section 3 only after the charging current 11 has completely finished flowing and the DC high voltage 6 has been established.

In one example, the time from when the power supply 10 is turned on until the ready signal 4 rises (is supplied) is 600 ms.

FIG. 4 is a diagram showing how voltages, currents, signals, etc. of each part change over time during startup of an embodiment of the present invention.

The explanatory symbols are the same as in FIG. 2. As explained above, according to the present invention, it is possible to easily prevent the display control unit from malfunctioning due to charging current to high-voltage parts upon startup, and to reduce the need for shielding each part and the This has the effect that restrictions on placement are greatly relaxed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional CRT display device, FIG. 2 is a time chart showing the operation of each part at startup of the conventional CRT display device, FIG. 3 is a diagram showing an embodiment of the present invention, and FIG.
The figure is a time chart showing the operation of each part at the time of startup of an embodiment of the present invention. 1... CRT, 2... Scanning and high voltage generation section, 3... Display control section, 4... Operation town signal, 5...・Synchronization signal, 6...DC high voltage for electron beam acceleration, 7...CRT display control signal, 8...Synchronization signal generator, 9...
... Capacity for accumulating DC high voltage, 10 ... Power supply, 10 ... Power supply, 11 ... High voltage section charging current.

Claims (1)

[Claims] 1. In a cathode ray tube display device including a cathode ray tube, display control section, synchronization signal generation section, scanning and high voltage generation section, etc., when starting up the display device, the synchronization signal generation section and the scanning and high voltage generation section are first started, and the cathode ray 1. A cathode ray tube display device, characterized in that the display control section starts operating after a high DC voltage for accelerating the tube's electron beam is established.