JPS606877Y2 - cathode ray tube display device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cathode ray tube display device that displays bright spots on the screen of a cathode ray tube and displays characters, figures, etc. by a collection of the bright spots.

As is well known, in a character display device using a cathode ray tube, which is used for computer terminal display, a switching type output amplification circuit that outputs only high and low levels can be used as a video output amplification circuit.

The advantages of the switching method are that the power supply voltage can be used at a good rate, up to nearly 100%, and the power consumption is low.In particular, the power consumption of the amplification transistor is very small, and the output level is fixed and cannot be adjusted. It's not necessary.

The disadvantages are that only high-level and low-level outputs can be displayed, so it is not possible to display the so-called halftone, which is the intermediate brightness between high and low levels that has been conventionally used, and that the output drive transistor It is difficult to obtain transistors with high breakdown voltage (usually 60 V or more) and good switching characteristics.

Therefore, the first object of the present invention is to provide a circuit that selectively displays the brightness of a bright spot displayed on a screen between a maximum brightness and a predetermined intermediate brightness.

Another purpose of this proposal is to enable the use of transistors capable of high-speed switching operations, that is, transistors with good switching characteristics such as rise, fall, and carrier accumulation times, as transistors for driving cathode ray tubes in the output stage. The object of the present invention is to provide a circuit that consumes small current in the output stage and can be used even with a drive transistor having a relatively low withstand voltage.

The present invention will be explained below with reference to FIG. 1, which is an embodiment drawing.

Reference numeral 1 denotes a video input terminal to which a video signal for displaying bright spots on the screen is input, and this video signal is composed of a predetermined binary signal read from a well-known refresh memory or the like.

Although this video signal is shown here as one that displays a bright spot using a positive pulse, it is also possible to input a negative pulse by installing an inverter in front of the video signal.

Reference numeral 2 denotes a control input terminal to which a control signal is input for displaying the brightness of a bright spot on the screen in so-called halftone. Here, by applying a positive pulse, halftone display, which will be described later, is performed.

Reference numeral 3 denotes a phase inverting circuit which inverts the phase of the above-mentioned video signal inputted from the terminal 1 and outputs the first video signal.

4 is an AND gate circuit that blocks the passage of the video signal input from terminal 1 when a control signal, that is, a positive pulse is applied to terminal 2; it passes while a negative pulse is applied to terminal 2; For convenience, the above-mentioned video signal that is used is referred to as a second video signal here.

Therefore, the first and second video signals have an opposite phase relationship with each other.

5 is the cathode K of the cathode ray tube 7 to which the first video signal is input.
A first video output circuit 6 for driving a second video signal is input to the control grid G of the cathode ray tube 7.
This is a second video output circuit for driving 1.

The first and second video output circuits 5 and 6 have exactly the same circuit configuration as shown in FIG.

Reference numeral 8 denotes a DC regeneration circuit which is required when driving the cathode ray tube 7 and the control grid G1 with a DC-cut signal by the capacitor C, and is constructed of a well-known type.

Therefore, a horizontal pulse is applied to the terminal 81 of this DC regeneration circuit 8, and a current is connected to the terminal 82.

The variable resistor 83 determines the DC clamp level of the control grid G1.

As is well known, in such a DC reproducing circuit 8, if the cathode of the cathode ray tube 7 is driven by a signal whose DC is cut off by a capacitor C, the control grid G is connected to the second video output circuit 6 except for the capacitor C shown in the diagram. If it is directly driven by the output, it is provided on the cathode side.

Such a configuration can be arbitrarily changed in design in the present invention.

The horizontal pulse applied to the terminal 81 is used to clamp the video signal during the blanking period so that the display brightness of the cathode ray tube does not vary due to changes in the video signal.

Further, the variable resistor 83 described above is used to set the display brightness level of the cathode ray tube.

As shown in FIG. 1, when the DC regeneration circuit 8 is provided on the control grid 01 side, the bright spot on the screen is the cathode ray tube 7.
It emits light when the signal applied to the cathode K of is negative, and emits light when the signal applied to the control grid G1 is positive.

At this time, the display brightness of the bright spot will be the maximum brightness level if it is driven by both the first and second video output circuits 5 and 6, which respectively provide outputs to the cathode K and control grid G1 described above. It is set so that

Furthermore, if the output of either the first or second video output circuit 5 or 6 is maintained constant at the "°H" level or the "Lp" level, a bright spot will be generated based on the output of the other one. Displayed in halftone.

The brightness level of this halftone is m/n with respect to the maximum brightness level of the first and second video output circuits 5 and 6, respectively.
,! : Set to share at the brightness level of '□.

However, n and m are positive integers and m<n.

For example, if the first video output circuit 5 is
If the cathode ray tube 7 is to be driven at a brightness of /3, the second video output circuit 6 is set to be driven at a brightness of 2/3.

In the example shown in FIG. 1, the setting is such that both parties share the burden by 1/2.

The first and second video output circuits 5 and 6 are respectively constituted by a pair of transistors 51.52 and 61.62 and switching transistors 53 and 63.

Each pair of transistors 51.52 and 61.62 is designed so as not to affect the switching characteristics of the switching transistor 53.63 by the capacitance of the cathode of the cathode ray tube 7 and the control grid G□. .

Also, a resistor 54.64 and a capacitor 55.65 are connected to the base of each switching transistor 53.63.
is provided for so-called speed-up to improve switching characteristics.

Here, the terminals 56 and 66 are connected to the power supply.

In the vertical magnetic deflection circuit according to the present invention having the above configuration, since the cathode of the cathode ray tube 7 and the control grid G1 are driven by the first and second video signals of opposite polarity, the first and second video output circuits 5, 6 terminals 56, 66
The power supply voltage applied to the
It can be designed to be as low as 25V, which is 1/2 of that.

Further, each of the transistors 51 to 53 and 61 to 63 may have a low breakdown voltage, for example, about 30 V, and transistors with good switching characteristics such as rise and fall times and carrier accumulation times can be used.

Furthermore, when the switching transistor 53 of the first video output circuit 5 is on, the switching transistor 63 of the second video output circuit 6 is off, so the maximum power consumption by both circuits 5 and 6 is designed to be small. be able to.

By the way, when a bright spot on the screen is to be displayed in halftone, a positive pulse is applied to the terminal 2 as already mentioned.

As a result, the output of the AND gate circuit 4 becomes the "L99 level," and the switching transistor 63 of the second video output circuit 6 stops switching operation in response to the second video signal as long as a positive pulse is applied to the terminal 2. be done.

As a result, a negative signal is correspondingly applied to the control grid G1 of the cathode ray tube 7.

Therefore, the cathode ray tube 7 receives the first video signal corresponding to the first video signal.
Only the cathode is driven by the output of the video output circuit 5, and the bright spots on the screen are displayed in halftone.

As already mentioned, the display brightness of the bright spot on the screen at this time depends on the power supply voltage applied to the terminal 56 of the first video output circuit 5 and the power supply voltage applied to the terminal 66 of the second video output circuit 6. It can be determined by appropriately determining the voltage ratio between

As described above, the present invention can optionally display bright spots on the screen in halftones or with the same display brightness as before, but this halftone display can be performed using a second As shown in the figure, the output of the AND gate circuit 4 is applied to the phase inversion circuit 3, the cathode K of the cathode ray tube 7 is maintained constant at the "H1f level, and the control grid G1 is driven in accordance with the second video signal. However, the same effect can be obtained.

Furthermore, a circuit equivalent to the AND gate circuit 4 in FIG. 2 described above is provided at the position shown in FIG.
The gist of the present invention is not changed by configuring the display brightness of the halftone to be displayed to be arbitrarily selected by selectively operating the gate circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a block circuit diagram showing another embodiment of the present invention. 3...Phase inversion circuit, 4...Gate circuit, 5...First video output circuit, 6...
Second video output circuit, 7...Cathode ray tube, 8...
...DC regeneration circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] A cathode ray tube display device that displays characters, figures, etc. by volatile points on the screen of a cathode ray tube in response to a predetermined binary signal, which responds to an input first video signal. a first video output circuit that drives a cathode of a cathode ray tube so as to give a negative brightness level value with respect to a maximum brightness level value of a bright spot on the screen; and a second video signal having a polarity opposite to that of the first video signal. In response to the signal, n
- a second video output circuit that drives a control grid of the cathode ray tube to provide a brightness level value of m/n; A cathode ray tube display device comprising a circuit that selectively applies voltage to each of the output circuits and alternately controls on/off operation of the first and second video output circuits according to the signal. However, m and n are positive integers and m<n.