JPH0546105A - Picture quality controller - Google Patents

Abstract

PURPOSE:To realize excellent picture quality with an easy operation by enabling a contrast and brightness to be adjusted at the same time, and varying the contrast greatly at the center part of an adjustment range and also varying the brightness greatly at end parts of the adjustment range. CONSTITUTION:A control circuit 23 controls a brightness adjusting circuit 21 and a contrast adjusting circuit 22 to indicate the brightness and contrast to be adjusted and when an operation part 24 is operated, the brightness and contrast are adjusted at the same time. In a nearly center range in 100% of the adjustment range, the brightness is fixed at a specific value and only the contrast is varied linearly from a minimum value to a maximum value. At the left-side end part and right-side end part of the adjustment range, on the other hand, the contrast is fixed at a specific value and only the brightness is adjusted and varied linearly. In this case, the brightness is held almost constant at the center part of the adjustment range and the contrast is held nearly constant at the right and left end parts, but they can slightly be varied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a television receiver,
The present invention relates to an image quality control device suitable for use in a monitor device or the like.

[0002]

2. Description of the Related Art For example, adjustment knobs for brightness (brightness) and contrast (picture) are provided in order to adjust the image quality of an image displayed on a television receiver. When the knob for adjusting the brightness is adjusted, the cathode voltage of the picture tube changes to adjust the brightness. Also, when the knob for contrast adjustment is adjusted, the amplitude of the luminance signal changes and the contrast of the screen is adjusted.
The user can appropriately adjust these knobs as necessary to obtain a desired image quality.

[0003]

In the conventional apparatus, since the dedicated knobs are provided for adjusting the brightness and the contrast, the adjusting operation is troublesome. Further, there is a problem in that it is difficult to understand the difference between the characteristics of brightness and contrast and it is difficult to control the two knobs independently to obtain good image quality. In particular, in the case of a vehicle-mounted device, the condition of external light changes significantly during the day and at night, so the frequency of adjusting the brightness or contrast increases more than it does indoors, but the complexity of the adjusting operation is not safe. It was a problem from the perspective of.

Therefore, a device for adjusting the brightness and the contrast in cooperation with one knob is also considered, but this adjustment is for adjusting the brightness and the contrast with the same characteristics as shown in FIG. However, there is a problem that it is difficult to obtain good image quality.

The present invention has been made in view of such a situation, and is to make it possible to easily realize a good image quality.

[0006]

The image quality control apparatus of the present invention is operated when a brightness adjusting circuit 21 for adjusting the brightness of an image, a contrast adjusting circuit 22 for adjusting the contrast, and a brightness and a contrast are simultaneously adjusted. Operation part 2
4 and the contrast adjustment circuit 21 such that the contrast changes more greatly than the brightness at the center of the adjustment range and the brightness changes more than the contrast at the end of the adjustment range when the operation unit 24 is operated. Two
And a control circuit 23 for controlling the two simultaneously.

[0007]

In the image quality control device having the above structure, the operation unit 2
When 4 is operated, brightness and contrast are controlled simultaneously. Then, at this time, the adjustment is performed so that the contrast changes more greatly than the brightness in the central part of the adjustment range and the brightness changes more than the contrast in the end part of the adjustment range. Therefore, good image quality can be realized by a simple operation.

[0008]

2 is a block diagram showing the configuration of an embodiment of a television receiver to which the image quality control device of the present invention is applied. The tuner 2 receives a radio wave of a predetermined broadcasting station by the antenna 1 and outputs an intermediate frequency signal thereof. The intermediate frequency amplification circuit 3 amplifies the intermediate frequency signal output from the tuner 2 and outputs the amplified intermediate frequency signal to the video detection circuit 4. The video detection circuit 4
The input output of the intermediate frequency amplifier circuit 3 is detected and a color video signal is output. This video signal is supplied to the video amplifier circuit 5 and amplified. The video amplifier circuit 5 supplies the luminance signal component of the input video signal to the video delay circuit 6, delays it for a predetermined time, and then outputs it to the video amplifier circuit 7. Also, the color signal component is output to the color signal reproducing circuit 9.
The primary color output circuit 8 synthesizes the luminance signal component output from the video amplifier circuit 7 and the color signal component output from the color signal reproduction circuit 9, and outputs the synthesized signal to the CRT 10.

In order to control the image quality of the image displayed on the CRT 10 in this manner, the video amplifier circuit 7 has a built-in brightness adjusting circuit 21 and contrast adjusting circuit 22, as shown in FIG. 3, for example. The brightness adjusting circuit 21 and the contrast adjusting circuit 22 are controlled by a control circuit 23 including, for example, a microcomputer. The operation unit 24 is operated when adjusting the brightness adjustment circuit 21 and the contrast adjustment circuit 22 at the same time, and outputs a signal corresponding to the operation to the control circuit 23.

The brightness adjusting circuit 21 can be constructed, for example, as shown in FIG. In this embodiment, the input luminance signal is supplied to the base of the NPN transistor 40 via the parallel circuit of the capacitor 31 and the resistor 33. The base of the NPN transistor 40 is grounded via the resistor 34 and the variable resistor 35. The other end of the variable resistor 35 is supplied with an ABL voltage from a circuit (not shown) and is grounded via a variable resistor 36 for auxiliary brightness adjustment. The collector of the NPN transistor 40 is grounded via the capacitor 32, and the resistor 37
Is connected to a predetermined voltage source via. Also, NPN
The emitter of the transistor 40 is grounded via the resistor 38, and the luminance signal output from here is resistor 39.
It is designed to be output via.

When the variable resistor 35 is adjusted, the base voltage of the NPN transistor 40 changes. As a result, NP
The potential of the cathode of the CRT 10 in which the emitter of the N-transistor 40 is DC-coupled via the resistor 39 is set to a predetermined value. The ABL voltage is a reference voltage for preventing the brightness from increasing above a predetermined level, and the variable resistance 36 for adjusting the auxiliary brightness sets the maximum brightness within the range of the ABL voltage.

The contrast adjusting circuit 22 is, for example, as shown in FIG.
Can be configured as shown in. In this embodiment, the luminance signal is supplied to the base of the NPN transistor 51 and is output from the collector of the NPN transistor 51 through the transformer 56. The emitter of the NPN transistor 51 is grounded via a parallel circuit of a resistor 54 and a capacitor 52 and a parallel circuit of a variable resistor 55 and a capacitor 53. Of the current output from the emitter of the NPN transistor 51, the direct current component flows through the resistor 54 and the variable resistor 55, and the alternating current component flows through the capacitor 52, a part of the variable resistor 55 and the capacitor 53. When the variable resistor 55 is adjusted, the resistance value in the AC component path changes. As a result, the AC gain of the NPN transistor 51 changes due to the bypass effect of the capacitor 53, and the amplitude of the luminance signal output from the collector changes. As a result, the screen contrast is adjusted.

In FIG. 1, the control circuit 23 has a brightness adjusting circuit 21.
And the brightness and contrast characteristics which are controlled and adjusted by the contrast adjustment circuit 22. As shown in the figure,
The brightness and contrast are adjusted at the same time by operating the operation unit 24. Then, in the adjustment range of 100%, the central range (from 20% to 30% to 7%
In the range of 0% to 80%), the brightness is fixed to a predetermined value, and only the contrast changes linearly from the minimum value to the maximum value. That is, in this range, the brightness does not change even if the operation section 24 is operated, and only the contrast changes.

On the other hand, the left end of the adjustment range (0%
To 20% to 30%) and right edge (70%
In the range from 80% to 100%), the contrast is fixed to a constant value, and the brightness is adjusted so as to change linearly. Of course, in the above description, the brightness is set to be substantially constant in the central portion of the adjustment range and the contrast is set to be substantially constant in the left and right end portions, but it may be changed slightly. In short, in each of these sections, it is sufficient that the other changes sufficiently with respect to the other.

By setting the characteristics in this way, it is possible to reproduce almost 100% luminance in the adjustment range of 20% to 30% to 70% to 80%. Then, for example, in the adjustment range of 20% to 30% or less, the brightness can be sufficiently reduced when the device is used in a vehicle-mounted device in a state where the external light is extremely small such as at night. Also, 70% to 8
In the range of 0% or more, it becomes possible to set the brightness sufficiently high, for example, when the surroundings are extremely bright. However, as described above, the brightness cannot be adjusted to be higher than the brightness defined by the ABL voltage.

In the above description, the brightness adjusting circuit 21 and the contrast adjusting circuit 22 are controlled by the control circuit 23 such as a microcomputer, but in addition to this, for example, a double volume control is used. It is also possible.

[0017]

As described above, according to the image quality control device of the present invention, it is possible to adjust the contrast and the brightness at the same time, and the contrast is changed more greatly than the brightness in the central part of the adjustment range and the contrast is adjusted at the end part of the adjustment range. Since the luminance changes more greatly than the contrast, good image quality can be realized by a simple operation.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the adjustment characteristics of brightness and contrast in the embodiment of FIG.

FIG. 2 is a block diagram showing the configuration of an embodiment of a television receiver to which the image quality control device of the present invention is applied.

FIG. 3 is a block diagram showing the configuration of an embodiment of the image quality control device of the present invention.

4 is a circuit diagram showing a configuration of an embodiment of the brightness adjustment circuit 21 of FIG.

5 is a circuit diagram showing a configuration of an embodiment of the contrast adjustment circuit 22 of FIG.

FIG. 6 is a diagram illustrating conventional brightness and contrast adjustment characteristics.

[Explanation of symbols]

 21 brightness adjustment circuit 22 contrast adjustment circuit 23 control circuit 24 operation unit

Claims (1)

[Claims] 1. A brightness adjusting unit for adjusting the brightness of an image, a contrast adjusting unit for adjusting the contrast of an image, an operating unit operated when adjusting the brightness and the contrast at the same time, and the operating unit is operated. At this time, a control means for controlling the brightness adjusting means and the contrast adjusting means at the same time is provided so that the contrast changes more greatly than the brightness at the center of the adjustment range and the brightness changes more than the contrast at the end of the adjustment range. An image quality control device characterized by.