JPH0346623Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a display device, in which white balance adjustment for color television broadcast reception and white balance adjustment for external equipment reception can be performed using a common level adjustment variable resistor. The purpose is to provide a display device.

Color television receivers require white balance adjustment to reproduce color images beautifully.

FIG. 1 shows a circuit diagram of essential parts of an example of a display device using a conventional color television receiver. This one is red, green from input terminals 1 ₁ to _{1 3} ,
The color difference signal for blue and the luminance signal from the input terminal 2 are mixed and supplied to the picture tube 3 such as a CRT, and the three primary color signals from, for example, a personal computer or a television camera are sent to the picture tube 3. This is an output circuit that can be used to receive external equipment. First, when adjusting _the highlight white balance for receiving television broadcasts, color difference signals (R _{- Y )} , (G-
Y), (B-Y), and a highlight luminance signal to the input terminal 2.

The color difference signals input to terminals 1 ₁ to 1 ₃ are supplied to transistors Q ₁ to Q ₃ , while the luminance signals input to terminal 2 are supplied to transistor Q ₄ , variable resistors R ₁ , R ₂ and resistor R ₃ ( It is supplied to the transistors Q ₁ to _{Q 3} through the resistors (each having a resistance value of around 200Ω), where it is mixed with the color difference signal and amplified, and then sent to the R, G,
It is supplied to the electrode corresponding to B. Variable resistance R ₁ ,
By appropriately adjusting _R2 , the levels of signals supplied to the electrodes corresponding to R and G are adjusted, and highlight white balance adjustment is performed.

Next, when adjusting the highlight white balance for external device reception, DC bias voltages V _A to V _C are supplied to input terminals 1 ₁ to 1 ₃ , while three primary color signals from a personal computer are supplied to terminals 4 ₁ to 4 ₃ . R,
G and B are supplied, and no signal is supplied to terminal 2.
The three primary color signals from terminals ₄₁ to ₄₃ are transferred to transistor _Q5.
~Q ₇ , variable resistors R ₄ , R ₅ and resistor R ₆ are supplied to transistors Q ₁ to _{Q 3} , where it is superimposed on a bias voltage and supplied to the picture tube 3 . Highlight white balance adjustment is performed by adjusting variable resistors R ₄ and R ₅ in the same way as in the above case.

Note that variable resistors R ₇ to _{R 9} are variable resistors for low light/white balance adjustment.

However, this conventional circuit uses variable resistors R ₁ and R ₂ for white balance adjustment for television broadcast reception.
and variable resistors R ₄ and R ₅ for white balance adjustment for external device reception are provided separately.
It has the disadvantage that it requires a large number of parts and is cumbersome to handle, as it requires both white balance adjustment for television broadcast reception and white balance adjustment for external device reception.

Further, variable resistors R ₁ , R ₂ and variable resistors R ₄ , R ₅ are provided separately, and variable resistors R ₁ to _{R 3} are provided separately.
Since the resistance value of is small, the three primary color signals R, G, B are mixed through the resistors R ₁ to R ₃ when receiving from an external device.
There is a drawback that crosstalk occurs between the three primary color signals and accurate three primary color signals cannot be supplied to the picture tube 3.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to FIGS. 2 and 3.

FIG. 3 shows a circuit diagram of a main part of an embodiment of the display device according to the present invention. In the figure, the same components as those in FIG. In the figure, ₅₁ to ₅₃ are switch circuits, and one of the switch circuits is made up of a pair of transistors whose emitters and collectors are connected to each other, and whose bases are connected in common. . One emitter-collector connection point of each of the transistors _X1 to _X6 constituting the switch circuits ₅₁ to ₅₃ is commonly connected to the emitter of the transistor _Q4 , while the other emitter-collector connection point is are connected to the collectors of transistors Q ₅ to Q ₇ , respectively, and variable resistors R ₁₀ and R ₁₁
and connected to the emitters of transistors Q ₁ to _{Q 3} via resistor R ₁₂ .

In this case, the variable resistors R ₁₀ and R ₁₁ are installed after the connection point between the luminance signal line in television broadcast reception and the three primary color signal lines in external equipment reception, so the variable resistors R ₁₀ and R ₁₁ are connected to the white It can be used in common for both balance adjustment and white balance adjustment using an external device, and by performing this adjustment only once, the white balance adjustment for both receptions is completed.

For example, when performing white balance adjustment using television broadcasting, the switch S is closed. As a result, the voltage of power supply +B is changed to switch S, resistor
It is supplied to the bases of transistors _X1 to _X6 via _R13 . On the other hand, the luminance signal shown in the second diagram that has entered the terminal 2 is supplied to _the transistor _Q4 , and during the period _t1 , the transistor _Q4 is off and _the transistors _X2 , ₂ is the transistor Q ₄ ,
X ₁ , X ₃ , and X ₅ are turned on.

In this case, the three primary color signals are not supplied to the terminals 4 ₁ to 4 ₃ and the transistors Q ₅ to _{Q 7} are in an off state.

Transistors X ₁ to X ₆ are activated by the above luminance signal.
It remains on for 1H period, and the signal from terminal 2 is supplied to transistors _Q1 to _Q3 via transistors _X1 to _X6 and resistors _R10 to _R12 , where it is mixed with the color difference signal and amplified. and supplied to the picture tube 3. Here, highlight white balance adjustment is performed by appropriately adjusting variable resistors R ₁₀ and R ₁₁ .

In this way, the variable resistor R ₁₀ for level adjustment,
Since _R11 is installed after the connection point between the luminance signal line and the three primary color signal lines, once you adjust the highlight white balance using television broadcasting, you can of course adjust the white balance for receiving television broadcasting, and also adjust the white balance for external equipment. This means that the white balance for reception has also been adjusted, so there is no need to use an external device to adjust the white balance.

Next, when adjusting the white balance using an external device, the switch S is opened and the color killer circuit (not shown) of the chroma circuit is operated. By opening switch S, _transistor
〜X ₆ is in the off state, while the level V _A shown in the second diagram is applied to the terminals 1 ₁ to 1 ₃ due to the operation of the killer circuit.
A DC bias voltage with V _B and V _C is applied.

The three primary color signals R, G, B from, for example, a personal computer inputted to the terminals 4 ₁ to 4 ₃ are transmitted to the transistors Q 1 to _{Q 3 via} transistors Q ₅ to Q ₇ , variable resistors R ₁₀ , R ₁₁ , and resistor R ₁₂ . Here, it is superimposed on a DC bias voltage and supplied to the picture tube 3. Here, highlight white balance adjustment is performed by appropriately adjusting variable resistors R ₁₀ and R ₁₁ .

In this case, since the transistors X ₁ to X ₆ are in the off state, the three primary color signals from the terminals 4 ₁ to 4 ₃ are not mixed, and no crosstalk occurs between them.

Note that the image receiving device is not limited to a CRT, and it goes without saying that other display devices may be used.

As mentioned above, the display device according to the present invention has one terminal commonly connected to the luminance signal input terminal and the other terminal connected to each separate level adjustment variable resistor between the luminance signal input terminal and the output transistor. The output transistors are connected to the switch circuits separately connected to the respective output transistors through the external device, and the output transistors are connected to the input terminals of the three primary color signals from the external equipment through the level adjustment variable resistors, thereby making it possible to receive television broadcasts. It is possible to use a variable resistor that performs white balance adjustment for external device reception and white balance adjustment for external device reception in common, and the configuration can be configured with fewer switches than conventional equipment in which these are provided separately, and also for television broadcasting. It is easier to handle than conventional equipment that uses signals from both to adjust the white balance, and it is easier to handle than conventional equipment that adjusts the white balance using signals from both. Since a switch circuit is provided between the signal input terminal and the luminance signal input terminal, the three primary color signals coming from external equipment are not mixed with each other, and no cross talk occurs between each other. It has the characteristics that it can be supplied to

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the main parts of an example of a conventional device;
The figure shows the television signal waveform and the potential at each point, and FIG. 3 is a circuit diagram of the main part of an embodiment of the device of the present invention. 1 ₁ to 1 ₃ ... Color difference signal and DC bias input terminal, 2 ... Luminance signal input terminal, 3 ... Picture tube, 4
₁ ~ 4 ₃ ... External device three primary color signal input terminal, 5 ₁ ~
5 ₃ ...Switch circuit, _Q1 to _Q3 , _X1 to _X6 ...Transistor, _R10 , _R11 ...Variable resistor for level adjustment, S...Switch.

Claims (1)

[Scope of utility model registration request] A circuit that mixes and amplifies color difference signals and luminance signals for red, green, and blue of a color television signal using output transistors and supplies them to a receiver, and a circuit that mixes and amplifies the color difference signals and luminance signals for red, green, and blue of a color television signal, respectively, and supplies the signals to a receiver, and the three primary color signals of red, green, and blue from an external device. In a display device provided with a circuit that separately amplifies the luminance signal with the output transistor and supplies it to the image receiving device, one terminal is commonly connected between the input terminal of the luminance signal and the output transistor. A switch circuit is connected to the input terminal and the other terminal is separately connected to the output transistor through a separate variable resistor for level adjustment, respectively, and the input terminal of the three primary color signals is connected to the input terminal for adjusting the level. A display device in which the output transistors are connected via a variable resistor.