JPS5929427Y2 - Television receiver display device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the improvement of a display device for a television receiver.
In particular, the present invention relates to a display device for a television receiver that displays information such as a reception channel number on the screen.

By combining a frequency synthesizer or a voltage synthesizer with a microcomputer and a character generator, one-on-one instantaneous channel selection is possible, and at the same time,
When the channels are displayed superimposed on the screen, the same location on the cathode ray tube is always kept in a high brightness state, which tends to cause burn-in on the phosphor screen or uneven characteristics, and is also an eyesore for viewers. Therefore, a method is adopted in which the display is erased after a certain period of time after channel switching, etc.

However, if the display time of such channels, etc. is always set to a fixed time (for example, 5 seconds) from the time of operation, when the receiver is turned on after not being used for a long time, In addition, the warm-up time of the cathode ray tube (usually 1
(5 to 20 seconds), information such as the channel is displayed on the screen, but by the time the receiver is activated, the channel display time has already expired, and there are cases where no channel display is performed after that. arise.

On the other hand, set a long information display time for the above channels etc. only when the power is turned on (for example, 20 to 25 seconds).
However, if the receiver is turned on while the CRT heater is preheated to some extent, the channels will be displayed at the same time, so channels will be displayed on the screen for a considerable period of time. As a result, the drawbacks of the conventional example described above are reproduced.

In view of the drawbacks of the conventional example, the present invention adopts a configuration in which the information display time of channels etc. is constant, and when the power is turned on, the start of the display always coincides with the time when the beam current flows approximately normally. This is an attempt to overcome the various drawbacks of the conventional example.

The details of the present invention will be explained below with reference to FIGS. 1 and 2 showing main circuit block diagrams, FIGS. 3 and 4 showing main part circuit diagrams, and FIG. 5 showing operation waveform diagrams. do.

As shown in Fig. 1, the device of the present invention is as follows:
A television operating circuit 10 that generates a control output in response to television reception operations such as channel switching, and a display time setting circuit 20 that uses this output as a starting point to determine the end of channel display, etc. (a microcomputer or the like may be used) and the characters (letters,
numbers, etc.).

It is comprised of a display signal output circuit (for example, MM-5841 manufactured by National Semiconductor) 40 and a delay circuit 50, which is a feature of the present invention.

FIG. 2 shows a block diagram of the delay circuit 50. As shown in FIG.

The circuit basically includes an R-S flip-flop circuit 51, a power-on detection circuit 52, and a differentiation circuit 5 whose input is the output.
Set (or preset) pulse generation circuit 5 consisting of 3
4, a beam current detection circuit 55 that detects the operation of the cathode ray tube, and a reset (or clear) pulse generation circuit 56 that resets the R-S flip-flop circuit 51 at the predetermined level. , will be understood with reference to FIGS. 3 and 4 together.

The power-on detection circuit 52 allows any circuit voltage (FIG. 5A) generated when the receiver is powered on.

On the other hand, various embodiments of the beam current detection circuit 55 can be considered, but as shown in FIG.
It is most efficient to reuse the circuit configuration.

That is, the known ABL circuit applies a control voltage of 120 V to the first control grid 31 of the cathode ray tube 30 via series resistance circuits R1, R2 and R3, and
A diode D1 is connected in the forward direction between the connection point 01 of the resistors R1 and R2 and the ground, and between the connection point 01 and the cold terminal of the high voltage winding 32 of the flyback transformer FBT and the connection point 02 of the bypass capacitor C. Connect resistor R6 for beam current detection to
In the case of , the diode D1 is in a conductive state, so the potential at point 01 is kept approximately constant. However, when an excessive beam current flows, the diode D1 is in a conductive state due to the voltage drop across the resistor R6.
becomes non-conductive, and the current flowing through resistors R2 and R3 is
becomes equal to the beam current, and the connection point of resistors R2 and R3 is 0.
3, a beam control voltage is generated.

ABL is distantly related by utilizing this control voltage to control the video circuit.

As described above, the voltage at point 01 also changes as the beam current changes.

(See Figure 5) Therefore, this output is used as the beam current detection voltage.

The judgment level for beam current detection is the Zener diode D2.
The resistors R7, R8 and the transistor T are set as follows.
A reset pulse generation circuit 56 is formed.

The R-S flip-flop circuit 51 is
It may also be configured with a pair of D circuits.

In such a circuit configuration, when the power of the receiver is turned on and an output as shown in FIG. ), and the output becomes high level as shown in Figure 5.

Next, when the voltage at point 01 in the circuit in FIG. 4 (gate in FIG. 5) is applied to the input terminal B of the delay circuit as the power is turned on, a reset pulse, which is the emitter output of transistor T1, is applied to the input terminal B of the delay circuit. The output of the generating circuit 56 is applied to the R-S flip-flop circuit 51 in a shaped form as shown in FIG. 52 to reset it.

Therefore, the R-S flip-flop circuit will not be reset unless triggered by the power-on detection signal again, and will not malfunction in the beam current detection output.

Therefore, if the display time setting circuit 20 is configured to be controlled at the falling edge of the output pulse as shown in FIG.
After the cathode ray tube becomes operational, the display of channels, etc. will be for a certain period of time (for example, 5 seconds), which is the same as when switching channels.
will be displayed, and the various drawbacks of the above-mentioned conventional example will be corrected.

According to the present invention, even when the receiver is started, the channel information on the screen is always displayed for a certain period of time in the operating state, so there is no unevenness in display or non-display, and there is no influence of the display on the cathode ray tube. This also eliminates the conventional disadvantages of being an eyesore to viewers.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the main part of the circuit, Fig. 2 is a block diagram of the main part of the delay circuit, Fig. 3 is an implementation circuit diagram of the delay circuit, Fig. 4 is an example of the implementation circuit of the beam current detection circuit, FIG. 5 is an explanatory diagram of operating waveforms. Explanation of main drawing numbers, 52...Power-on detection circuit,
55... Beam current detection circuit, 50...
・Delay circuit, 20...Display time setting circuit, 40
...Display signal output circuit.

Claims (1)

[Scope of utility model registration request] A flip-flop that is set by a power-on detection signal when the power is turned on and reset by the output of a beam current detection circuit in a television receiver configured to display information such as a reception channel number on the screen for a certain period of time as the device is operated. A display device for a television receiver configured to determine the beginning of said information display by the trailing edge of a circuit output pulse.