KR820001832Y1 - Tv picture control device - Google Patents

Abstract

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Description

Screen adjustment device

1 is a circuit diagram for explaining the principle of the present invention.

2 is a main circuit diagram of a television receiver showing an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: CdS element 2: Correction circuit

3: image amplifier circuit 4: band amplifier circuit

R ₃ : Screen adjustment variable resistor R ₁₈ : Luminance adjustment variable resistor

R ₇ , R ₈ , R ₂₄ , R ₂₅ : Self-adjusting insertion resistance

SW ₁ , SW ₂ , SW ₃ : Automatic, Manual Switch

The invention particularly relates to a screen adjustment device most suitable for use in color television receivers.

Applicant first of all, according to the Japanese Utility Model Registration Application Digestion 49 (AD 1974) -1572 and the Utility Model Registration Application Digestion 49 (AD 1974) -31013, etc., the brightness, contrast, A device for automatically adjusting color saturation using ambient light is proposed. Therefore, the outline of the apparatus according to the above application will first be described.

In Fig. 1, reference numeral 1 denotes a photoelectric conversion element such as CdS, R ₁ and R ₂ are divided resistors, T ₁ is a control transistor, R ₃ is a variable resistor for operating range adjustment, (2) a correction circuit, and (3) Is an image amplification circuit, (4) is a band amplification circuit, L is ambient light, V _C1 , V _C2 is a DC control voltage, and (5) and (5 ') are power supply terminals. SW ₁ is an automatic or manual switch and has contact points a and m. R ₄ is a split resistor, and 6 is a display lamp.

In the above circuit, when knocking over the switch SW ₁ on a side, eunghaeseo the brightness around the external light L, and the resistance value of CdS (1) change, through a resistor R _1, R ₂ voltage change due thereto transistor When applied to the base of T ₁ , the collector voltage at point A in the figure changes from zero to the power supply voltage. The DC voltage change at this point A is applied to the correction circuit 2 through the resistor R _3, and the DC resistance voltages V _C1 and V _C2 of an appropriate ratio are obtained by the division resistors constituting this circuit. Applying a direct current control voltage V _C1 to video amplifier circuit 3, and can adjust the brightness and contrast of the screen by controlling the output level and the gain, and applying a direct current control voltage V _C2 in band amplifier 4 its gain By controlling, the color saturation can be adjusted. That is, for example, when the ambient appearance L becomes bright, the voltage at the point A decreases, thereby brightening the screen, increasing the contrast, and decreasing the color saturation again. In this state, the display lamp 6 is turned on to indicate that the circuit is in the automatic adjustment state. Further Improperly installed over the switch SW ₂ m side, is de eoeo A point is in manual adjustment state, by adjusting the resistor R _3, it is possible to adjust the display manually.

By the way, viewers who rely on various automatic adjustment devices provided in color television receivers are generally not used to various handles for manual adjustment, and therefore rarely touch these handles, and therefore, the handles are left fixed. I throw away a lot.

In the case of the automatic screen adjustment apparatus, the following problems occur with respect to the brightness adjustment knob as a handle for the manual, for the first degrees of the variable resistor R ₃ to handle related thereto.

When the ambient light of the receiver is bright and the screen luminance is high, and the screen luminance is high, the circuit of FIG. 1 is easily caught by the ABL (automatic beam adjustment), and the luminance adjustment knob has a cut-off point of the water pipe. Although it is adjusted to match with the black part of, although it is installed in any variable range according to the nonuniformity of the broadcasting station, the nonuniformity of the receiver, the user's preference, etc., even if this variable resistance is set to the maximum, it is roughly normal by the ABL. You can see the screen. By the way, when the periphery of the receiver becomes dark, the brightness is automatically tightened. However, if the variable resistor of the brightness adjusting knob is set to the maximum, the brightness is not tightened and the entire screen is stuck.

In addition, when a first-degree variable resistor R ₃ is accessed by the movable end to the A point side when the resistance to the upper limit value is designed so that the maximum sensitivity. Therefore, in the auto-adjustment state, when this movable terminal approaches the point A and the opposite side and the resistance is set to the lower limit value, the terminal voltage is fixed to the power supply voltage, so that the control voltage cannot be obtained even when the ambient light changes.

As described above, in the screen automatic adjusting device as shown in FIG. 1, the screen for adjusting the brightness and the knob of the movable terminal of the variable resistor R ₃ are fixed to the wrong position and left unfavorably.

The present invention is to solve the problem that the above-mentioned screen is blurred, in particular, to reduce the change range of the control voltage of the passive brightness adjustment circuit during automatic adjustment.

An embodiment of the present invention will be described with reference to the drawings.

2 shows the main part of the television receiving circuit according to the present invention, and the same parts as those in FIG. R ₅ is a sensitivity adjusting resistor of CdS (1), R ₆ is a split resistor, R ₇ is a resistor connected in series with the variable resistor R _3, and R ₈ is a resistor connected in parallel with R ₈ , R ₇ . SW ₂ is a switch, which has contacts a, m and interlocks with the switch SW _1, and when the contacts are closed to the contact a side, the resistors R ₇ and R ₈ are inserted and connected. The values of the resistors R ₇ and R ₈ are selected such that when the maximum value of the variable resistor R ₃ is 5 m, for example, R ₇ is 10 m and R ₈ is about 6.8 mV. And R ₂₆ is the emitter resistance of transistor T ₁ . C ₁ is a capacitor connected between the base and the collector of the transistor T ₁ , and due to the meter effect caused by the resistance and the time constant of R _2, the ambient light L suddenly drops, for example, when a person passes through the front of the screen. If it is changed, the circuit does not respond. The capacitor C ₁ is closed when the switch SW ₁ is closed to the m side. Since a side is added and a reverse voltage is applied, a bipolar capacitor must usually be used. However, since the base and collector of the NPN transistor T ₁ are diodes of PN, the collector side, Even if the side is admitted, the diode is forward with respect to the reverse voltage, so the base voltage hardly rises and the capacitor C ₁ is not destroyed. Therefore, as the capacitor C _1, a monopolar one can be used as shown in the figure. Thus, in a meter circuit having a switch SW ₁ for the collector side, an inexpensive unipolar capacitor can be effectively used.

Next, in Fig. 2, the water tube of (7), (8) is a color demodulation circuit, (9) is a matrix circuit, (10) is a composite color television signal input terminal, and (3a) is an image amplification circuit (3). The contrast control circuit in (3), 3b, is also a luminance control circuit. Reference numeral 11 denotes a high voltage circuit including a flyback transformer, a rectifier circuit and the like, which obtains an ABL signal through the transmission line 12 and applies it to the luminance control circuit 3b in a known manner.

R ₉ , R ₁₀ are… … R ₁₇ and C ₂ are resistors and capacitors constituting the correction circuit 2 shown in FIG. 1, and the DC voltage change obtained through the variable resistor R ₃ at point A as described above is appropriately sized by these resistors and capacitors. It is to be the voltage of. In this correction circuit, the voltage obtained by the variable resistor R ₁₂ is further divided by the resistors R ₉ and R ₁₀ to obtain a control voltage V _C2, which is applied to the band amplifier circuit 4. The voltage divided by the resistors R ₁₄ and R ₁₅ becomes the control voltage V _C1 , which is applied to the brightness control circuit 3b through the resistor R ₁₇ and again to the contrast control circuit 3a through the resistor R ₁₆ . .

R ₁₈ is a variable resistor for adjusting luminance, and the voltage obtained at this movable terminal is obtained by a resistor R ₁₈ . … The signal is divided through R ₂₃ and capacitors C ₃ , C ₄ , C _5, and the like to be the luminance adjustment voltage V _C1 ′, and is applied to the luminance control circuit 3b.

R ₂₄ and R ₂₅ are divided resistors inserted into a circuit to obtain the luminance adjustment voltage V _C1 ′, and SW ₃ has contacts a and m as switches and interworks with the switches SW ₁ and SW ₂ . When the switch SW ₃ is closed to the contact a side, the resistors R ₂₄ and R ₂₅ are inserted and connected. The resistance R _24, the size of the R ₂₅ when the 1㏀, R ₂₂ to 27㏀, R ₂₀ to 820㏀, R ₂₁ a resistor R ₂₃ to 56㏀, R ₂₄ is 12㏀, R ₂₅ is 20㏀ degree uigap Is selected. And each capacitor C ₂ . C ₄ is to slow the response of the circuit.

Thus, when de eoeo the point A by closing the switch SW ₁ toward m, in association this switch SW _2, SW ₃ it is also closed towards each m. At this time, the resistors R ₇ , R ₈ and R ₂₄ , R ₂₅ are not connected and the circuit is in a manual adjustment state. By changing the variable resistor R ₃ in this state, the respective control voltages V _C1 and V _C2 change to adjust the luminance, contrast and chromaticity to the taste. Further, each can independently adjust the brightness by the colors of grapes by the variable resistor R ₁₂ to the variable resistor R _18. In the present embodiment, the A adjustment point is set to the manual adjustment state, but the manual adjustment can also be made by fixing the A point to the potential of the other adjustment.

Closed, then the switch SW ₁ on the side a, the switch SW _2, SW ₃ also closes the side a, resistors R _7, R ₈ and R _24, R ₂₅ is be connected to the circuit is automatically adjusted state. At this time, even though the movable terminal of the variable resistor R ₃ approaches the resistor R ₇ side and the resistance value is set to the minimum, the voltage change of the point A can be obtained from the movable terminal by the resistors R ₇ and R ₈ , and the change of the ambient light L The screen can be adjusted automatically in response. In this case, since the voltage change range due to the variable resistor R ₃ is reduced, the sensitivity can be finely adjusted by moving the movable terminal.

In addition, since the change width of the voltage obtained by the luminance adjusting variable R ₁₈ is also reduced by the resistors R ₂₄ and R ₂₅ , the luminance control voltage V _C1 ′ does not change very much. For this reason, when the ambient external light L of the receiver becomes dark, even if the movable terminal of this variable resistor approaches the power supply side and the resistance value is maximum, the V _C1 luminance is lowered by the control voltage, and the screen can be prevented from being disturbed. In addition, the variable resistor R ₁₈ can be used as a crude.

The present invention provides a photoelectric conversion element (for example, photoelectric conversion element 1) that detects stepping on ambient light, and a first variable resistor connected in series to a variable impedance element whose impedance changes in response to the output of the photoelectric conversion element ( For example, R ₈ , a second variable resistor (for example, R ₁₈ ) for dividing a predetermined voltage, and a first control voltage (for example, V _C1) obtained for the mover of the first variable resistor. ) And a brightness adjusting circuit (e.g., brightness control circuit 3b) supplied with a second control voltage (e.g., V _C ') obtained to the mover of the second variable resistor, and the variable at the time of manual brightness adjustment. the connection point between the impedance element and the second variable resistor of the first (for example, point a), a predetermined potential (e.g. eoeo de potential) means for fixing (for example the switch SW ₁₎ and, wherein the automatic brightness adjustment Bottle in the passage for supplying a second control voltage to the brightness adjusting circuit Be connected to the screen relates to an adjustment device made in each of a resistor (for example, R _24, R ₂₅₎ for reducing the variation range of the control voltage of the second.

Therefore, according to the present invention, even when the movable resistor for manual adjustment of the potentiometer for manual brightness adjustment is biased toward the power supply side, the screen does not become blurred, and a good screen is always obtained despite the automatic adjustment or manual adjustment.

Claims (1)

A photoelectric conversion element for detecting the brightness of ambient light, a variable impedance element whose impedance changes in response to the output of the photoelectric conversion element, a first variable resistor connected in series with the variable impedance element and a predetermined voltage are divided. A luminance adjusting circuit and passive luminance adjustment supplied with a second variable resistor, a first control voltage obtained for the mover of the first variable resistor and a second control voltage obtained for the mover of the second variable resistor. Means for fixing a connection point between the variable impedance element and the first variable resistor at a predetermined potential at a time, and connected in parallel to a passage for supplying the second control voltage to the luminance adjustment circuit during automatic luminance adjustment. And a resistor for reducing the change range of the second control voltage.