JPH02292985A - Convergence correcting device for video projector - Google Patents

Abstract

PURPOSE:To prevent the variance of the convergence CV and color slurring even though the vertical width has fluctuation due to a wrong signal source, etc., by constituting the device so that the transfer of signals between a deflecting circuit and a CV circuit is attained. CONSTITUTION:A waveform signal flowing in a deflecting yoke 1 is taken out of a deflecting circuit 2 and inputted to a control circuit 3. The lowest point of a waveform is set at 0V for generation of a DC voltage waveform having the same potential as the peak value of the waveform signal. At the same time, a reference waveform signal generated by a reference wave generating circuit 10 of a control circuit 4 is amplified by an amplifier 11 up to an amplitude equal to the reference voltage 12. The output of the amplifier 11 is combined with various reference waveform signals via an adjustment control circuit 13. Then a CV signal is outputted to a CV circuit 5 for execution of the prescribed CV correction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] This invention relates to a convergence correction device for a video projector that is configured to automatically correct convergence deviations due to variations in the vertical width of the video projector. [Prior Art] Figure 6 is a block diagram of a conventional convergence correction device for a video projector. In the figure, (20) is a cathode ray tube, (1) is a deflection yoke that is attached to the neck of the cathode ray tube (20) and vertically deflects the electron beam, and (2) is a deflection yoke that is attached to the neck of the cathode ray tube (20).
) is a deflection circuit that operates the deflection yoke (1), (0
is a control circuit that outputs a control signal to correct convergence. (5) is a convergence circuit, which outputs a convergence signal according to the control signal output from the control circuit (0). (B) is the cathode ray tube (20).
A sub-yoke attached to the neck of the motor receives the convergence signal output from the convergence circuit (5) and performs convergence correction. This sub yoke (
8) and the deflection yoke (1) constitute an electron beam deflection means (30).

Next, the operation of the above configuration will be explained. A video projector generally combines pictures of three cathode ray tubes emitting red-mφ blue light onto a screen surface through a lens provided within the projector. At this time, a slight color shift occurs. In order to eliminate this color shift, convergence correction is performed to correct the image reflected on the cathode ray tube, thereby creating a single image on the screen with no color shift. Here, according to the conventional video projector convergence correction device having the above configuration, the main deflection is performed by the deflection circuit (2) and the deflection yoke (1). On the other hand, in the control circuit (4), as shown in FIG.
, (b), and (c) are generated, and the combined signal shown in FIG. 4(d) is input to the convergence circuit (5). This convergence circuit (5) amplifies the above input signal and then amplifies the sub-yoke (
By inputting to 6), the convergence correction necessary to combine red, green, and blue without color shift is performed. [Problems to be Solved by the Invention] The conventional convergence correction device for a video camera is configured as described above, so that once the convergence has been adjusted, when the signal source is changed, etc. When the vertical width varies, the electron beam deflection means (
Deflection yoke (1) and sub-yoke (6
), only the deflection yoke (1) operates, and the sub-yoke (6) continues to be adjusted. Therefore, for example, even if the convergence is adjusted at the time of shipment from the factory, there is a possibility that the convergence may shift due to a difference in the signal source on the user's side, resulting in color shift in the image. Therefore, there have been problems in that the quality of the image is degraded and that it takes a lot of effort for the user to readjust the shifted contrast.

This invention was made to solve the above-mentioned problems, and it is a video projector that can prevent convergence shift and color shift even if the vertical width varies due to differences in signal sources. The purpose is to provide a convergence correction device. [Means for Solving the Problems] A convergence correction device for a video projector according to the present invention includes a control circuit that receives an output signal from a deflection circuit and outputs a corresponding control signal, and a convergence correction device that is controlled by the control signal. It is characterized by being equipped with a control circuit that outputs a control signal for performing correction. [Operation] According to the present invention, the amplitude signal that is the output of the deflection circuit is detected, and the convergence correction operation is performed according to the detected amplitude signal, thereby automatically correcting the convergence shift regardless of the vertical width fluctuation. In addition to being able to correct color shifts in images, it is also possible to prevent color shifts from occurring in images. [Embodiment of the Invention] An embodiment of the invention will be described below based on the drawings. FIG. 1 is a block diagram of a convergence correction device for a video projector according to an embodiment of the present invention, and in the same figure, (1). (2). (4) ~ (B), (20), (
30) are the same as the conventional example shown in FIG. 6, so they are given the same reference numerals and detailed explanation thereof will be omitted. In Figure 1, (3) is a control circuit, and this control circuit (
3) inputs the amplitude signal output from the deflection circuit (2) and outputs a corresponding control signal to the control circuit (0). Figure 2 is a block diagram showing a specific example of the configuration of the control circuit (0). 4. In the figure, (10) is a reference waveform generation circuit, which generates the reference waveform signals shown in FIGS. 4(a) to (d). (11) is an amplifier, which generates the reference waveform. The reference waveform signal generated by the circuit (10) is amplified until it has the same amplitude as the reference voltage (12), which consists of two amplification standards: a horizontal component amplification reference and a vertical component amplification reference. (13) In the adjustment control circuit, the above amplifier (1
A convergence signal is output to a convergence circuit (5) by combining various waveform signals output from the convergence circuit (5). Next, the operation of the above configuration will be explained. Figure 3 (a
). (b). 3(c) is a waveform signal used in the control circuit (3) of FIG. 1, and the waveform signal of FIG. 3(a) is constantly flowing through the deflection yoke (1). This waveform signal is extracted from the deflection circuit (2). This extracted waveform signal is input to the control circuit (3), and as shown in Fig. 3(b), the lowest point (P) of the waveform is set as Ov, and from there the same potential as the peak value (Q) of the waveform signal is set. Create the DC voltage waveform shown in Figure 3 (0). On the other hand, the reference waveform signals generated in the reference waveform generation circuit (10) of the control circuit (4) are as shown in FIGS. Amplify to the same amplitude as (l2). At this time, the amplification reference voltage of the horizontal component is kept constant, and the amplification reference voltage of the vertical component is set to the voltage waveform shown in Fig. 3 (C). Make it proportional to the voltage waveform in figure (C). Then, the output of the amplifier (11) is sent to the adjustment control circuit (11).
In 3), the various reference waveform signals described above are combined and a convergence signal is output to the convergence circuit (5), and a predetermined convergence correction is performed. FIG. 5 shows a configuration diagram of a convergence correction device for a video projector according to another embodiment of the present invention. In this figure, the difference from the embodiment shown in FIG. 1 is that the deflection circuit (
A synthesis amplifier circuit (21) that synthesizes the output of 2) and the output of the convergence circuit (5) and outputs a signal that causes simultaneous deflection and convergence by the deflection yoke (1).
Since the other configurations are the same as in FIG. 1, the same reference numerals are given to the corresponding parts and their explanation will be omitted. In the embodiment shown in FIG. 5, the electron beam deflection means (30) is composed of the synthetic amplification circuit (21) and the deflection yoke (1), so the sub-yoke (6) can be made unnecessary.

[Effects of the Invention] As described above, according to the present invention, since the configuration is such that signals are transmitted across the deflection circuit and the convergence circuit, the convergence also changes in response to changes in the deflection circuit. Regardless of variations in vertical width due to differences in signal sources, convergence shifts can be automatically corrected and quality degradation due to image color shift can be suppressed. Additionally, there is no need to readjust convergence, which saves time and effort on the user's part.

[Brief Description of the Drawings] Fig. 1 is a block diagram of a convergence correction device for a video projector according to an embodiment of the present invention, Fig. 2 is a block diagram showing a specific structure of a control circuit, and Fig. 3 is a signal diagram of the control circuit. FIG. 4 is a waveform diagram of a convergence reference signal; FIG. 5 is a configuration diagram of a convergence correction device for a video projector according to another embodiment of the present invention; FIG.
The figure shows the configuration of a convergence correction device for a conventional video projector. (1) Deflection yoke, (2) Deflection circuit, (3
)...control circuit, (4)...control circuit, (
5) Convergence circuit, (20) Braun tube, (3o) Electron beam deflection means. Note that the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A deflection circuit that outputs a signal for vertically deflecting the electron beam of a cathode ray tube, a control circuit that receives the output signal from this deflection circuit as input and outputs a corresponding control signal, and outputs from this control circuit. a control circuit that is controlled by a control signal and outputs a control signal for correcting convergence; a convergence circuit that outputs a convergence signal according to the control signal output from the control circuit; and a convergence circuit that is connected to the convergence circuit and the deflection circuit. A convergence correction device for a video projector, characterized in that it is equipped with an electron beam deflection means.