JPS6325560B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color temperature control device for a picture tube of a television receiver.

1. Configuration of conventional example and its problems FIG. 1 shows an example of an output circuit of a conventional picture tube. In the figure, 1, 2, 3 are color difference signals, 4 is a luminance signal, 5, 6, 7 are driving transistors, 8,
9, 10 are gain adjustment volume, 11, 12, 13
is the picture tube cut-off adjustment volume, 14,1
5, 16, 17, 18, 19 are load resistors, 20 is a picture tube, 21, 22, 23 are picture tube grid voltage generation circuits 24, 25 are power supplies, 26, 27, 28
are cathode signals for each color. The operation of adjusting the white balance of the picture tube 20 in this output circuit will be described below. When you want to project white on the picture tube, white balance adjustment is performed by adjusting the volumes 11, 12, DC of each color signal by 13
The level is adjusted, and the gain of each color signal is adjusted using volumes 8, 9, and 10. Figure 2 a shows the grit cathode tube voltage of each color signal R, G, B of the picture tube.
FIG. 3 is a characteristic diagram of V _GK versus beam current I _B. Note that R represents red, G represents green, and B represents blue. Now, in FIG. 2b, first, at point A where the beam current is relatively small, the DC level is matched to one point using the volumetric controls 11, 12, and 13, and the beam current is adjusted. Furthermore, at point B where the beam current is relatively high, the gain is adjusted by the volumetric controls 8, 9, and 10, and the beam current characteristics are adjusted as shown in FIG. 2c. Although the light emission state and the beam current do not necessarily match, in reality, the color temperature on the surface of the picture tube is measured and the white balance is adjusted. As shown in FIG. 1, once the white balance is adjusted using the volume, it is necessary to turn the volume to change the operating point, which requires considerable effort. Next, let us consider the case where we try to adjust the color temperature. The color temperature is determined by cathode signals 26, 27, and 28 in FIG. Generally speaking, changing the color signal with the white balance adjusted means changing the gain to change the cathode voltage of the picture tube, as shown in Figure 3.
6, 27, and 28, and by changing the beam current. For example, as shown in Figure 3a,
If the blue gain of B is increased and the red gain of R is decreased to make the image bluish, white characters will appear whiter, resulting in an image suitable for viewing the characters. Further, as shown in FIG. 3B, if the red gain of R is increased and the gain of B blue is decreased to make it appear red, the image will have a warmer feel.
By changing the color temperature in this way, it is possible to obtain an image that is optimal for the display content. However, with conventional output circuits, once the white balance is taken,
In order to change the color temperature, it is necessary to adjust the volumes 8, 9, and 10, and an adjustment jig is also required, which requires considerable effort.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
It is an object of the present invention to provide a device that can easily control the color temperature of a picture tube.

Configuration of the Invention A color temperature control device according to the present invention includes a picture tube, an output circuit that drives the picture tube, and a circuit that controls the gain of the output circuit, and controls the gain of the output circuit for each color signal. By doing this, the color temperature is controlled.

Description of Embodiments In recent years, devices for processing or controlling television signals using digital data have been developed in television receivers, such as digital signal processing circuits of microcomputers. Fourth
The figure shows a basic digital signal processing television receiver. In FIG. 4, 31 is a control microcomputer, 32 is an operation key, 33 is a remote control transmitter, 34 is a remote control signal receiving circuit, 3
5 is a storage element, 36 is a channel selection circuit, 37 is a tuner, 38 is an intermediate frequency amplification circuit, 39 is a digital signal processing circuit, 40 is a color output circuit, 41 is a drive circuit, 42 is a picture tube, and 43 is an audio output circuit. , 44 is an audio output device.

The basic operation of FIG. 4 will be explained below.

A microcomputer 31 for control by a signal from an operation key 32 or a remote control transmitter 33
determines the operation, and stores the memory element 35, the channel selection circuit 36,
Controls the signal processing circuit 39 and the like. Tuning data and data serving as initial values for signal processing are stored in the storage element 35, and are read and written as appropriate.
First, when a tuning operation is performed, the tuning circuit 36 operates and drives the tuner 37 to send the video and audio signals obtained there through the intermediate frequency amplification circuit 38 to the digital signal processing circuit 39. send to The digital signal processing circuit 39 converts the input signal into a digital signal, performs video and audio signal processing, performs various controls according to instructions from the control microcomputer 31, and sends the color signal 46 to the color output circuit 40. Add. This color output circuit 40 can adjust the DC level and gain of the color signal using digital data 45 from the control microcomputer 31. The adjusted signal is applied to the drive circuit 41 to drive the picture tube 42. on the other hand,
Audio signal 47 is applied to audio output circuit 43 to drive audio output device 44 .

Now, in FIG. 4, color temperature control is performed by determining a color temperature switching command from the operation key 32 or the remote control transmitter 33 by the control microcomputer 31, and changing the color temperature of the color output circuit 40 stored in the storage element 35. Reads the gain control data and sends the result of the calculation with the color temperature control data to the color output circuit 40,
This is done by changing the gain of the color output circuit 40.

In the circuit shown in FIG. 4, a specific circuit for color temperature control according to the present invention is shown in FIG. FIG. 5 shows the color output circuit 40, drive circuit 41, and picture tube 42 extracted from FIG. 4 as parts necessary for explaining the present invention.

In FIG. 5, 40 is a color signal output circuit, 41 is a picture tube drive circuit, and 42 is a picture tube. 51,
52 and 53 are digital signal processing circuits 39 in FIG.
D/A converters 54, 55, which convert the three color output digital data processed by the
56 is an amplification circuit that amplifies the color signal, 57, 58,
59 is a picture tube drive circuit; 60, 61, and 62 are picture tube cathode voltages; and 63, 64, and 65 are amplifier circuits 5
4, 55, 56 DC level adjustment circuit, 66, 6
7 and 68 are gain adjustment voltages of the amplifier circuits 54, 55, and 56.

Now, consider the case where the white balance is adjusted in the color signal output circuit 40 and drive circuit 41 shown in FIG.

First, the color signal data is sent to the D/A converters 51 and 5.
2, 53 convert it into an analog signal and send it to an amplifier 54,
Add to 55 and 56. The DC levels of the signals of the amplifiers 54, 55, 56 are adjusted by control voltages 63, 64, 65, and the gains are adjusted by control voltages 66, 67, 68. Therefore, as shown in the conventional example, the white balance is adjusted by adjusting the DC level and gain of each color signal in the amplifiers 54, 55, and 56.

The outputs of the amplifiers 54, 55, 56 are applied to drive circuits 57, 58, 59 to drive the picture tube 42.

Next, color temperature control according to the present invention will be explained. In FIG. 5, if the signals 60, 61, and 62 are red, green, and blue color signals, and are E _R , E _G , and E _B , the color temperature T can be expressed using a certain function F as follows. can.

T=F(E _R , E _G , E _B ) (1) The color temperature T is determined by the ratio of the cathode voltage of the picture tube 42. Now, if the color temperature when the white balance of the picture tube 42 is adjusted is T ₀ , then T ₀ =F(α ₀ E _R +a, β ₀ E _G +b, γ ₀ E _B +c)...(2) expressed. Here, α ₀ , β ₀ , γ ₀ are gains when the white balance is adjusted, and a, b,
c is also when the white balance is adjusted.
It is at DC level. Now, as an example of color temperature control, we will consider a method of changing the gain of each color output. The color temperature T _R when the color temperature is lowered, that is, when the color is reddish, is expressed as T _R = F (α ₁ E _R , β ₁ E _G , γ ₁ E _B ) …(3), and is basically ｜α ₁ ｜＞｜α ₀ ｜、｜γ ₁ ｜＜
By setting |γ ₀ |, the color temperature can be lowered as shown in FIG. 3b. Also, when the color temperature is increased, that is, when the color temperature is made blue,
T _B is expressed as T _B =F (α ₂ E _R , β ₂ E _G , γ ₂ E _B ) …(4), and basically |α ₂ |<|α ₀ |, |γ ₂ | ＞
By setting |γ ₀ |, the color temperature can be increased as shown in FIG. 3a.

Next, FIG. 6 shows an example of a specific gain control method for changing the color temperature. Figure 6 shows
This is a specific example showing one of the amplifier circuits 54, 55, and 56 shown in FIG. In FIG. 6, 71 is a color signal, 72 is an amplifier circuit, 73 is a color output signal, and 74 is a color signal.
DC level adjustment voltage, 75 is gain adjustment voltage, 76,
77 is a D/A converter, 78 and 79 are data registers, 80 and 81 are control digital data, 82 is a functional block of the control microcomputer 31, 83 is an arithmetic circuit, and 84 is a memory data reading circuit. , 85 is a color temperature switching circuit, 86 is a color temperature switching signal, 87 is a functional block of the memory element 35, 88 is gain data for adjusting the white balance, and 89 and 90 are data for changing the color signal. , 91 is DC level data with white balance adjusted.

The operation will be explained below with reference to FIG.

First, consider outputting a color signal with the white balance adjusted. The memory 87 stores 88 α ₀ , β ₀ , γ ₀ as gain data, and 91 a, b, c as DC level data. These data are read out by a memory data reading circuit 84 of the control microcomputer 82 corresponding to 31 in FIG. 4, and each gain data 88 is added to the data register 79 as data 81 without being calculated. D/A converter 7
7, it is D/A converted and applied to the amplifier circuit 72 as a gain control voltage 75 to adjust the gain of the color signal. Further, the level data 91 is added to the register 78 and subjected to D/A conversion by the D/A converter 76.
It is applied to the amplifier circuit 72 as a DC level control voltage 74 to adjust the DC level of the color signal and maintain white balance.

In this way, in the present invention, the color output circuit 40
The gain and DC level of can be controlled with digital data. Further, the data can also be stored in the memories 87 and 35.

Next, consider the case of switching the color temperature. For example, when a command to lower the color temperature is input from the color temperature switching signal 86, the control microcomputer 82 determines this, drives the color temperature switching circuit 85, and informs the memory data reading circuit 84 that the color of the memory 87 is It works to read data 89 of temperature "1". The read data 89, α ₁ , β ₁ , γ ₁ are white-balanced data α ₀ , β ₀ , γ ₀ and the arithmetic circuit 8
Gain data 81 calculated with 3 and lowered color temperature
The signal is sent to the data register 79 as a signal and controls the gain control voltage 75. When the color temperature is to be increased, the data 90 for the color temperature "2" is read out from the memory 87 and data for controlling the gain is sent in the same manner as described above to control the gain of the amplifier circuit 72.

As described above, in this embodiment, each color signal is
Since the DC level and gain can be adjusted using digital data, color temperature can be controlled by simply changing the value of the gain data, making it possible to set any color temperature. In FIG. 6, the color temperature data 89 and 90 in the memory 87 may be fixed values.

Effects of the Invention As described above, according to the present invention, in a digital signal processing circuit that can control the DC level and gain of a color output circuit using digital data, white balance adjusted data is stored in a storage element as a standard value. Then, by calculating the standard data and the second data according to a color temperature control command and outputting the resultant data to the color output circuit as digital data, arbitrary color temperature control can be easily performed.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional example of a color signal output circuit, Fig. 2 a, b, and c are explanatory diagrams of how to take white balance, Fig. 3 a, b are explanatory diagrams of color temperature adjustment, and Fig. 4 5 is a block diagram of a digital television receiver including a color temperature control device according to an embodiment of the present invention, FIG. 5 is a circuit diagram showing a specific circuit example of the embodiment of the present invention, and FIG. 6 is an explanation of the present invention. FIG. 31... Microcomputer, 32... Operation key, 33... Remote control transmitter, 34... Remote control signal receiving circuit, 35... Memory element, 39... Digital signal processing circuit, 40... Color output circuit, 41
... Drive circuit, 42 ... Picture tube, 51, 52, 5
3... D/A converter, 54, 55, 56... amplifier circuit, 57, 58, 59... drive circuit.

Claims (1)

[Claims] 1. A picture tube that emits three different colors, an output circuit that outputs three color signals to drive the picture tube, and a control that controls the color temperature of the picture tube screen by controlling the gain of the output circuit. and the control circuit stores standard digital data representing the gain of the output circuit when the color temperature is controlled to a standard color temperature, and at least one change digital data for changing the color temperature from the standard state. a memory element for selectively reading out the standard digital data and the digital data for change from the memory element, and a memory for reading out the digital data for change from the memory element at the time of color temperature switching. At least a color temperature switching means for controlling the data reading means, and an arithmetic circuit for creating control data to be supplied to the output circuit so as to change the color temperature based on the standard digital data and the changing digital data. Color temperature control device.