JPS61114664A - Television receiver - Google Patents

Abstract

PURPOSE:To increase degree of circuit integration by detecting a characteristic change of a picture tube from an anode current of the picture tube and adjusting automatically the characteristic change of each picture tube depending on the detection so as to eliminate the need for re-adjustment at a secular change of a picture tube and reducing number of external connection terminals. CONSTITUTION:One terminal of the secondary coil of a flyback transformer is connected to common via a resistor R and a capacitor C1, a voltage drop of the resistor R1 is a characteristic detection signal of a picture tube 41, and a DC detection signal Vc is obtained via a differentiation circuit comprising R2, C2, an amplifier 44, a diode D1 and a capacitor C3. When an R-Y color difference signal is fed from a chrominance circuit 22 to a bias circuit 23, a switch 33 is thrown to the position to supply the detection signal Vc to a line l11 synchronously with an output signal of a counter circuit 32. Similarly, the detection signal Vc is fed to a line l12 at the supply of a G-Y signal and the detection signal Vc is fed to a line l13 at the supply of a B-Y signal. The circuit operation is executed as above, resulting that bias adjustment in response to an individual characteristic of the picture tube 41 is attained automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a television receiver, and is suitable for use in various electronic devices equipped with a picture tube, such as a display device.

[Background technology]

Taking a television receiver as an example, it is equipped with a variable resistor to adjust errors in circuit characteristics, and a variable resistor to electrically adjust mechanical errors in the electron gun installed in the picture tube. It is being

The above-mentioned mechanical error appears as, for example, a change in the Eg-IP characteristics of the picture tube, and the cutoff voltage differs depending on the individual picture tube.

For this reason, "Color TV Textbook (Part 1)" (July 1980)
Published 13th edition on March 10th, Publisher: Japan Broadcasting Publishing Association, p1
41) are provided with variable resistors shown as V Rq to V Rg, so that the difference in the cutoff voltage, in other words, the error can be corrected.

By the way, according to the study of the present inventor, the variable resistor is usually attached to the so-called neck part of the picture tube, and therefore wiring and adjustment work are time-consuming.
It has been revealed that this is one of the reasons for the rise in production costs.

Furthermore, since many of the electronic circuits are integrated circuits, the number of external connection terminals inevitably increases, which is undesirable because it reduces the degree of integration and causes an increase in cost.

〔the purpose〕

An object of the present invention is to detect changes in the characteristics of the picture tube from the anode current of the picture tube, and thereby automatically adjust the changes in the characteristics of each picture tube, thereby enabling production at low cost and easy handling. The purpose is to provide an easy television receiver.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief summary of the invention disclosed in this application is as follows:
It is as follows.

That is, a change in the anode current of the picture tube is detected, and the detected signal is fed back to the signal output circuit that supplies video signals and color signals to the picture tube so as to be superimposed on the bias voltage, and is adjusted to match the characteristics of the picture tube. This achieves the object of the present invention, which is to automatically perform the adjustment.

〔Example〕

Next, an embodiment of a television receiver to which the present invention is applied will be described with reference to FIGS. 1 and 2.

Furthermore, Figure 1 shows the circuit configuration of a television receiver.
FIG. 2 shows the circuit configuration of the main part.

The television receiver is assumed to be constructed of a semiconductor integrated circuit (hereinafter referred to as IC), although not particularly shown.

The feature of this embodiment is that a change in the anode current is detected from one end of the flyback circuit, and the detected signal is superimposed on the bias voltage of the video output circuit as shown in FIG.
The reason is that the variable resistors for low light adjustment that were provided for each of the G and B output circuits have been removed. In addition, the above R
, G, and B indicate red, green, and blue color signals, respectively.

First, the overall circuit operation will be described.

2 is a receiving antenna, 2 is a high frequency amplification circuit, 3 is a mixing circuit, and 4 is a local oscillation circuit. Since the operations of these circuits are well known to those skilled in the art, their explanation will be omitted.

The circuit block 10 is also known to those skilled in the art, and 11 is a video intermediate frequency circuit that supplies a video intermediate frequency signal to the next stage video detection circuit and also outputs audio to an audio circuit (not shown). ] To supply Kakakara. A composite color television signal V is output from the video detection circuit 13.
d and a luminance signal Y are obtained, and the former is supplied to the band amplification circuit 21 and the synchronous separation circuit 31.

The delay circuit 14 is for synchronizing the delayed color signal with the delayed signal Y, and the delayed luminance signal Y is amplified by the video amplification circuit 15 and then sent to the primary stage video output circuit 16. Supplied.

By the way, although not shown, a filter circuit is provided between the video amplifier 13, the band amplification circuit 21, and the synchronous separation circuit 31, and a chroma signal is supplied to the band width circuit 21. The synchronization separation circuit 31 is supplied with horizontal and vertical synchronization signals.

First, regarding the color signal processing system, reference numeral 22 is a chroma circuit including a color demodulation circuit, and each color difference signal of RY, G=Y, and B-4 is supplied to the output circuit 16.

On the other hand, a horizontal synchronization signal H and a vertical synchronization signal V are obtained from the synchronization separation circuit 31, and the former is supplied to a horizontal drive circuit and the latter to a vertical drive circuit (none of which is shown), and the conventionally known circuit operation is performed. It is carried out. At the same time, the horizontal synchronization signal H
is supplied to the counter circuit 322.

The counter circuit 32 counts the horizontal synchronizing signal H, and for example, when the scanning line is 18th, 19th, or 20th, the switch circuit 33
This is for supplying a detection signal Vc, which will be described later, to the bias circuit of the output circuit 16 by sequentially switching over the detection signal Vc. In other words, there are 525 scanning lines, of which 6.5
%, 35 lines corresponds to the vertical retrace period, and the above 18 to 2
The 0th scan line is included within the vertical blanking period. Therefore, the adjustment of the bias voltage using the detection signal Vc is performed during the vertical retrace period before the image is displayed, so as to prevent the screen from shaking due to bias voltage adjustment while the image is being displayed. It is considered. Note that a specific method of bias voltage adjustment will be described later with reference to FIG. 2.

Next, detection of characteristics of the picture tube 41 will be described.

A plate voltage is supplied to the plate 42 of the picture tube 41 from a high voltage circuit 43. The high voltage circuit 43 itself is well known to those skilled in the art, and its explanation will be omitted. However, one end of the secondary coil of a flyback transformer (not shown) is connected to a resistor R1 through a capacitor CI. Grounded. Therefore, the voltage drop across the resistor R1 changes in response to changes in the current of the picture tube 41, and the voltage drop becomes a characteristic detection signal for the picture tube 41.

Resistor R2 and capacitor C2 constitute a differentiating circuit, which detects the change in beam current that occurs when a color difference signal with a constant amplitude is supplied to the picture tube 41 during the vertical retrace period, and the difference is amplified by amplifier 44.

Diode D1. The capacitor C3 performs rectification and smoothing operations, and the detection signals when the R-Y, G-Y, and B-Y color difference signals are supplied to the picture tube 41 are converted into DC signals.

What should be noted here is the supply timing operation of the detection signal based on the output signal of the counter circuit 32.

That is, the chroma circuit 22 corresponds to the 18th scanning line.
The R-Y color difference signal is supplied to the bias circuit 23, and in synchronization with this, the switch 33 outputs the detection signal Vc to the line 11.
can be switched to supply . As a result, the RY color difference signal is supplied to the base of the transistor Q1 shown in FIG. 2, and the detection signal Vc is supplied to the emitter.

Therefore, the emitter of transistor Q has a resistor R1□
, the Y signal is supplied via the capacitor CI□, and the detection signal Vc is further supplied.

The emitter voltage is determined by the added voltage of both, and the current corresponding to the voltage level is passed through the resistor R83.
It flows through transistor Q1 and resistor R12.

A voltage drop occurs across the resistor R13 due to the above current, and this is output to the picture tube 4 as an output voltage containing the luminance signals Y and R color difference signals.
This means that bias adjustment is performed in accordance with the characteristics of the picture tube 41. Since the voltage level of the detection signal Vc is held by the capacitor C@, the bias voltage does not change over one vertical scanning period, and no image fluctuation occurs.

When the G-Y signal is supplied, the detection signal Vc is switched to appear on the line 112 by the output signal of the counter circuit 32. and transistor Q28. Low anti-R21
+ RZ! +R2:1 +Circuit block (2) constituted by capacitor C21 operates in the same manner as circuit block I, and adjusts the bias of the picture tube 41 in the same manner as described above. In addition, capacitor C! The operation of s is also the same as above.

When the B-Y signal is supplied, the detection signal Vc is switched to appear on the line 113 by the output signal of the counter circuit 32. Transistor Q31° Resistor R31v
The circuit block (2) composed of R32t R33r capacitors 631 operates in the same manner as the circuit blocks I and TI described above, and performs the bias adjustment of the picture tube 4I in the same manner as described above.

Note that the operation of the capacitor C4 is also the same as above.

As a result of the above circuit operations, bias adjustment is automatically performed in accordance with the individual characteristics of the picture tube 41, making it possible to display extremely good images without manual adjustment.

〔effect〕

(1) Since the characteristics of the picture tube are detected and the bias voltage at the time of signal supply is automatically adjusted based on the detection signal, a variable resistor for manual adjustment can be omitted. This effect can be obtained.

(2) Due to the above (1), there is no need to perform re-alignment even if the picture tube changes over time.

(3) The above (1) has the effect of reducing production costs.

(4) According to (1) above, the number of external connection terminals can be reduced when integrated into an IC, and the degree of integration of the IC can be improved.

Although the invention made by the present inventor has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. stomach.

For example, in the above embodiment, the bias heel pressure of the video output circuit is adjusted using the detection signal, but instead of this, the bias voltage of the picture tube may be adjusted.

[Application field]

In the above summary, the case where the invention made by the present inventor is applied to a television receiver, which is the background field of application, has been mainly explained, but the invention is not limited thereto.

For example, it can be used for color monitor devices and display devices.

The present invention can be used in various electronic devices including at least a picture tube.

[Brief explanation of the drawing]

FIG. 1 shows a circuit block showing an embodiment of a television receiver to which the present invention is applied, and FIG. 2 shows a circuit diagram of main parts for explaining the circuit operation. 16...Output circuit, 2I...Band amplifier, 22...
Kumalo circuit, 23... Bias circuit, 31... Synchronization separation circuit, 32... Counter circuit, 33... Switch circuit, 41... Picture tube, 42... Plate, 4
3...High voltage circuit-Qll + Q12I Q3...
・Tongister, R1 to R33...Resistance, C1 to C31
...Capacitor, Vc...Detection signal. Agent Patent Attorney Akio Takaro −＼ （、、、”'j ′１

Claims (1)

[Claims] 1. Detects the current change in the anode path of the picture tube, and sequentially feeds back the detection signal to the input circuit of the picture tube to control the bias voltage when supplying the signal, thereby adjusting the bias corresponding to the characteristics of the picture tube. A television receiver characterized by automatic adjustment.