JP2605290B2 - Focus adjustment circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus adjustment circuit for simplifying lens focus adjustment and set white balance adjustment when a projection type color receiver is installed.

2. Description of the Related Art In general, the drive voltage vs. emission luminance characteristics of each phosphor of a projection tube used in a projection type color receiver, as shown in FIG. Tends to saturate in the high input power region, and there is a restriction that the white color temperature must be lowered by adjusting the white balance of the receiver. In order to alleviate the luminance saturation of the blue phosphor as much as possible and to increase the white color temperature, the focus adjustment of the blue projection tube is usually set to an overfocus state which is advantageous in terms of luminance saturation characteristics.

However, in this state, the optimum focus adjustment of the projection lens is not easy because the display screen is blurred and the visibility of the blue light emission color is lower than the other two colors.

In a normal projection type color receiver, as shown in FIG. 4, one correction waveform (a mixture of static focus and dynamic focus waveforms) is supplied to each projection tube by one focus adjustment volume. Focus adjustment.

Therefore, taking the installation adjustment of a normal two-body projection type color receiver as an example, first, the focus adjustment of the projection tube is adjusted to the just focus state by the adjustment booms 2, 5, and 6. Next, the lens of each projection tube is adjusted to bring it into a just focus state on the screen surface. Thereafter, the focus adjustment volume 2 of the blue projection tube is turned in the overfocus direction to adjust the white balance.

Problems to be Solved by the Invention However, originally, the white balance adjustment is uniquely determined irrespective of the subjectivity of the adjuster, and as shown in the installation adjustment means, each time the installation is adjusted, the adjustment volume is turned. It is inconvenient to repeat the white balance adjustment after confirming and adjusting the lens focus by breaking the white balance state and setting the focus to just focus.

The present invention is intended to simplify focus adjustment by having two types of correction waveforms, a just focus state and an overfocus state.

Means for Solving the Problems In view of the above problems, the present invention has two types of focus adjustment waveforms, and switches between the two types of waveforms with a switch to select one of the set values, thereby providing a projection type. The correction waveforms necessary for the lens focus adjustment and white balun adjustment of the color receiver are supplied to the blue projection tube.

Operation The present invention solves the inconvenience of the focus adjustment in each of the projection lens focus adjustment and the white balance adjustment by the above configuration, and realizes the simplification of the adjustment of the administration type color image receiving.

Embodiment An embodiment of the present invention will be described below with reference to the drawings, taking an electromagnetic focusing CRT as an example.

FIG. 1 shows an embodiment of a force switching adjustment circuit according to the present invention.

1,2,3 and 4 are the electric focus volume of the blue projection tube,
Reference numeral 19 denotes a focus adjustment mode changeover switch for selecting mode A or mode B. In this embodiment, the mode A is set to the electric focus just state for adjusting the focus of the projection lens,
Assuming that the mode B is in the electric overfocus state for white balance adjustment, the switch 19 is set to mode A at the beginning of installation of the projection type color receiver, and the focus of the projection lens is adjusted. Next, when the switch 19 is set to the mode B, the white balance adjusted at the beginning is obtained.

In this configuration, the dynamic focus waveform in mode A and the dynamic focus waveform in mode B are different as shown in FIG.

This is because the focus of a normal projection tube is good at the center and poor at the periphery. Therefore, when the white balance is obtained by over-focusing the electric focus of the blue projection tube, it is preferable to over-focus only at the center of the blue projection tube. Therefore, the dynamic focus waveforms in mode A and mode B are shown in FIG. As shown in FIG. In FIG. 2, (a) is the input vertical parabolic wave voltage, (b) is the vertical parabolic wave voltage in the electric focus just state, and (c).
Indicates vertical parabolic wave voltages in an electric focus over state.

By adjusting the focus of the blue projection tube according to the procedure described above, the just-focus state and the over-focus state can be selected by switching the switch. As a result, there is no need to perform white balance adjustment again for the projection lens focus adjustment at the time of installation.

In FIGS. 1 and 4, reference numerals 5 and 6 denote green and red dynamicformer volumes, respectively, reference numerals 7 and 8 denote green and red focus regulators, and reference numerals 9, 10, and 11 denote blue, green, and red current amplifiers, respectively. , 13, and 14 indicate blue, green, and red focus coils, respectively.

Effect of the Invention As described above, the present invention has a two-mode independent focus adjustment function by switching a switch, and
There is a feature that the focus adjustment at the time of installing the projection type color receiver can be simplified.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a focus adjustment circuit according to an embodiment of the present invention, FIG. 2 is a dynamic focus waveform supplied to a blue projection tube, (a) is an input waveform, (b) is an electric focus just state, (b) FIG. 3C is a waveform diagram of the electric focus over state, FIG. 3 is a diagram showing drive voltage vs. emission luminance characteristics of the projection tube, and FIG. 4 is a circuit diagram of an embodiment of a conventional focus circuit. 1 ... mode A blue focus volume, 2 ... mode A
Blue dynamic focus volume, 3… Mode B blue focus volume, 4… Mode B blue dynamic focus volume, 5,6… Green, red dynamic focus volume, 12,13,14 …… Blue, green, red focus coil , 19 ... Mode switch.

Claims (1)

(57) [Claims] 1. A means for setting a focus current or a focus voltage supplied to a projection tube of a projection type color receiver to two kinds of correction waveforms, one of which is a waveform for converging the entire surface and the other is a uniform surface. A means for designating one of the two types of correction waveforms by switching between the two types of correction waveforms with a switch, a just-focus waveform necessary for lens focus or convergence confirmation adjustment, and a blue fluorescent material. A focus adjustment circuit that corrects light emission saturation in a high-luminance region and outputs an overfocus waveform required for realizing an appropriate white balance by switching with a switch.