JP2004208106A - Convergence device and projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a convergence device for realizing more accurate convergence correction even if the brightness of a display screen changes, and a projection display device. <P>SOLUTION: In the convergence device, first convergence correction data suitable for the display screen when it is brighter and second convergence correction data suitable for the display screen when it is darker are each stored in a memory capable of storing convergence correction data corresponding to a plurality of adjustment points on the display screen of a display device, the first and second convergence correction data read from this memory are mixed with each other in response to a detecting signal expressing the brightness of the display screen, and a convergence signal is generated using the convergence correction data from the mixing circuit and convergence signal is supplied to an auxiliary deflection coil. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a convergence device and a projection display device of a CRT display device such as a color television receiver and a projection television receiver.
[0002]
[Prior art]
Conventionally, convergence adjustment is required in a projection type television receiver (hereinafter, referred to as a three-tube type projector) including three CRTs (projection tubes) corresponding to R (red), G (green), and B (blue). Yes, digital convergence devices are generally known.
[0003]
For example, a digital convergence device disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 7-212797) is a digital memory in which M × N adjustment points are arranged on a display screen and convergence correction data corresponding to each adjustment point is stored. And interpolation processing means for creating interpolation data for filling the gaps between the adjustment points with low-pass filter characteristics using the data of the plurality of adjustment points read from the memory, and output from the interpolation calculation means. An auxiliary deflection amplifier for converting data into an analog signal and amplifying the current is provided, and a convergence correction signal is supplied from the amplifier to a convergence yoke attached to a projection tube neck.
[0004]
By using this device, the convergence can be corrected well, but no matter how well the convergence is adjusted, the convergence is shifted depending on the displayed pattern. This is due to a change in the screen amplitude caused by a high-voltage fluctuation (anode voltage fluctuation) of the projection tube.
[0005]
This phenomenon also occurs in an ordinary television receiver, and its generation principle will be described with reference to FIG. FIG. 5 shows a cross section of the picture tube 50, and a video signal is supplied to the cathode 505. Cathode 505 is heated by a heater (not shown) on its back. Usually, a cutoff voltage of about 200 V is applied to the cathode terminal. This voltage value is a voltage immediately before the electron beam is emitted from the cathode 505. If a lower voltage is supplied, the electron beam is emitted from the cathode 505. Normally, a high voltage of +20 kV to +30 kV called Eb is supplied to the anode terminal 500.
[0006]
Further, the anode terminal 500, the internal conductive film 501 in the tube, the aluminum film 502 deposited as a metal back treatment, and the final grid 503 are electrically connected. In the case of a picture tube provided with a shadow mask, the shadow is used. It is also electrically connected to a mask (not shown), and these are at the same potential. The electron beam output from the cathode 505 is accelerated by the high pressure supplied to the grid 503 and is emitted toward the display surface 507. A plurality of grids are arranged in the dotted line part 506 to focus the electron beam, but the description is omitted here. Further, horizontal and vertical deflection signals are supplied to the deflection coil 504, and an image is displayed on the display surface 507.
[0007]
NHK Television Textbook (above); edited by The Japan Broadcasting Corporation, pages 203 and 204, the length of the deflection coil 504 is 1 (cm), the strength of the magnetic field is H (Gauss), and the fluorescent screen is located from the center of the deflection coil. Assuming that the distance to the cathode is L (cm) and the anode voltage of the picture tube is Eb (V), the deflection amount h (cm) is
h = 0.3 × H × 1 × L / √Eb
It is described that it can be approximated.
[0008]
Further, since the amount of the electron beam emitted from the cathode 505 changes according to the brightness of the displayed image, the anode voltage Eb fluctuates depending on the brightness of the screen. From the above equation, for example, when Eb becomes smaller, h becomes larger even if other conditions are the same. This means that the screen amplitude increases as Eb decreases. Further, in the three-tube projector, the projection angles of the three projection tubes are different from each other, and convergence deviation occurs around the screen. In recent years, in order to reduce the projection distance, a design may be made in which the main axis of the projection tube is shifted. In this case, a convergence shift occurs even in the center of the screen.
[0009]
Japanese Patent Application Laid-Open No. 2001-157221 discloses an example of correcting a convergence shift due to such a change in anode voltage. The convergence device described in Patent Literature 2 generates a main convergence correction signal and a sub convergence correction signal, and changes the gain of the sub convergence correction signal by an electric signal that follows the change in brightness of the projection tube and the high voltage fluctuation. A new convergence correction signal is generated in addition to the main convergence correction signal.
[0010]
In this example, the convergence deviation can be effectively corrected with respect to the high-voltage fluctuation, but it is insufficient to realize more accurate convergence correction.
[0011]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 7-21779 [Patent Document 2]
JP 2001-157221 A
[Problems to be solved by the invention]
The convergence device of the conventional CRT type display device has a problem that the convergence is shifted when the brightness of the screen changes. SUMMARY OF THE INVENTION An object of the present invention is to provide a convergence device and a projection display device that realize more accurate convergence correction in order to solve this problem.
[0013]
[Means for Solving the Problems]
The invention according to claim 1 is a convergence device for a CRT type display device, wherein convergence correction data corresponding to a plurality of adjustment points on a display screen of the display device can be stored, and the brightness of the display screen is determined in advance. A memory for storing first convergence correction data suitable for a predetermined light state and a second convergence correction data suitable for a predetermined dark state; and the first read from the memory. A mixing circuit for mixing the second convergence correction data in accordance with a detection signal representing the brightness of the display screen; and using the convergence correction data from the mixing circuit to adjust the adjustment points and between the adjustment points. A convergence signal generation circuit for generating a convergence correction signal; and a sub-deflection coil to which the convergence correction signal is supplied. It is a convergence device, characterized in that Bei was.
[0014]
According to a fourth aspect of the present invention, in the convergence device for a CRT display device, convergence correction data corresponding to a plurality of adjustment points on a display screen of the display device can be stored, and the brightness of the display screen can be reduced. A memory for storing first convergence correction data suitable for the first state and offset data corresponding to a convergence shift amount when the brightness of the screen changes based on the first state; An addition circuit for multiplying the offset data read from the memory by a coefficient corresponding to a detection signal representing the brightness of a display screen and adding the multiplied coefficient to the first convergence correction data read from the memory And using the convergence correction data from the adder circuit, the convergence correction signal between the adjustment point and each adjustment point. A convergence signal generating circuit for generating; a convergence device, characterized in that the convergence correction signal; and a sub-deflection coil supplied.
[0015]
According to the convergence device described above, the convergence correction amount can be appropriately varied according to the brightness of the display screen, and the convergence deviation can be accurately corrected.
[0016]
The invention according to claims 9 and 10 is a projection type display device to which the above convergence correction device is applied.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a projection type display apparatus according to an embodiment of the present invention, and is a block showing an example of a three-tube projector.
[0018]
In FIG. 1, reference numeral 11 denotes an input terminal to which a video signal S1 is input, to which a video signal obtained by subjecting a television broadcast signal to reception processing by a tuner or a video signal provided from outside such as a VTR is input. The video signal S1 is supplied to the selection circuit 12, to which the video signal S2 for generating a convergence adjustment pattern is also input from the adjustment pattern signal generation circuit 13.
[0019]
The selection circuit 12 selectively outputs either the video signal S1 or the video signal S2 in response to a command from the microprocessor 15, and a command from an input device 14 such as a remote controller is supplied to the microprocessor 15. It is supposed to be. The video signal S1 or S2 selected by the selection circuit 12 is supplied to a video signal processing circuit 16, and the video signal processing circuit 16 converts the video signal into RGB signals based on the supplied video signal, and amplifies the signals. 173 respectively.
[0020]
The RGB signals amplified by the amplifier circuits 171, 172, and 173 are supplied to projection tubes 181, 182, and 183 corresponding to the three primary colors, respectively, and projected on the rear surface of the screen 19 via an optical system including a projection lens and the like. As a result, the projected images from the projection tubes 181, 182, and 183 are superimposed and displayed on the screen 19, and a color image is projected. This image is visually recognized by the viewer from the front side of the screen 19.
[0021]
On the other hand, the video signal selected by the selection circuit 12 is further supplied to a synchronization separation circuit 20, where the synchronization signal is separated and extracted. This synchronization signal is supplied to the main deflection signal generation circuit 21. The horizontal (H) and vertical (V) main deflection signals generated by the main deflection signal generation circuit 21 are supplied to main deflection coils mounted on the necks of the RGB projection tubes 181 to 183. The main deflection signal generation circuit 21 generates horizontal and vertical timing signals synchronized with the timing of each main deflection, and supplies the signals to the digital convergence circuit 22.
[0022]
Incidentally, a reflecting mirror is appropriately arranged between the three projection tubes 181 to 183 and the screen 19, and the image light projected from each of the projection tubes 181 to 183 is turned back to be guided to the screen 19. The device is made thinner. When viewed from above, the three projection tubes 181, 182, and 183 are inclined with respect to the R and B projection tubes 181 and 183, respectively, about the G projection tube 182 when viewed from above. The positional relationship between the screen 19 and each projection tube is different as shown in FIG. For this reason, even in the same projection tube, the projection distance is different between the central part and the peripheral part of the screen. In this state, the projected images of the respective colors of RGB do not overlap correctly, and distortion occurs.
[0023]
The digital convergence circuit 22 adjusts convergence in response to such a problem. The convergence circuit 22 receives a command from the microprocessor 15 and receives a synchronization signal from the main deflection signal generation circuit 21. Is entered. Then, horizontal and vertical auxiliary deflection signals (six types) corresponding to the respective projection tubes 181 to 183 are generated, and these six types of auxiliary signals are current-amplified by amplifier circuits 231 to 236, respectively. The signals are supplied to input terminals of horizontal and vertical auxiliary deflection coils 241 to 243 provided on the neck of the 183.
[0024]
The digital convergence circuit 22 according to the present invention is further characterized in that a detection signal that changes according to the brightness of the screen or a change in high voltage is supplied via the terminal 25. As a signal for detecting the brightness of the screen or the high voltage fluctuation, an ABL control signal is output from the high voltage generation circuit 26 connected to the main deflection signal generation circuit 21, and this ABL control signal is used as the above detection signal. do it. Alternatively, each of the RGB video signals may be integrated for a predetermined time, a signal indicating the brightness may be generated using the integrated value, and the signal may be used as a detection signal. Further, the above-mentioned drop of the high pressure Eb may be detected and this signal may be supplied.
[0025]
Next, the digital convergence circuit 22 of the present invention will be described in detail with reference to FIGS. FIG. 2 shows a display screen at the time of convergence adjustment. A cross hatch pattern composed of vertical lines and horizontal lines is displayed on the screen based on a signal from the adjustment pattern signal generation circuit 13, and each intersection of the cross hatch is displayed. An adjustment point is set at the position, and the convergence correction amount at each adjustment point is stored in the nonvolatile memory of FIG.
[0026]
In FIG. 3, the digital convergence circuit 22 has a nonvolatile memory 30, and the nonvolatile memory 30 stores data indicating the convergence correction amount of each adjustment point. The non-volatile memory 30 has a set of data that matches convergence correctly when the screen is bright (or when the high voltage drops) and a set of data that matches convergence correctly when the screen is dark (when the high voltage increases). Are stored, and both data are transferred to the memories 31 and 32 in response to a command from the microprocessor 15.
[0027]
The timing signal generation circuit 34 is based on the vertical and horizontal scanning timings supplied from the main deflection signal generation circuit 21, and controls the addresses and readouts of the memories 31 and 32 and the control signals required by the interpolation calculation unit 35. Generate control signals. Convergence data is read from the memories 31 and 32 at a predetermined timing synchronized with scanning, convergence data for a bright screen is read from the memory 31, and convergence data for a dark screen is read from the memory 32. .
[0028]
The mixing circuit 40 includes an A / D converter 41 for digitizing the detection signal of the brightness or high-voltage fluctuation of the screen supplied from the terminal 25, and a value K (0 ≦ k ≦ 1) output by the A / D converter 41. A multiplier 43 for multiplying the output of the memory 31; a (1-k) calculator 42 for calculating (1-k); and a multiplier 44 for multiplying the output of the (1-k) calculator 42 and the output of the memory 32. And an adder 45 for adding the outputs of the multipliers 43 and 44.
[0029]
Here, the two types of convergence data are appropriately mixed by the detection signal supplied from the terminal 25, and new convergence data is supplied to the interpolation operation circuit 35 at the next stage.
[0030]
For example, on the brightest screen, k = 1 and the data stored in the memory 31 is output from the mixing circuit 40. In the darkest scene, k = 0 and the data stored in the memory 32 is similarly output. In the case of an intermediate brightness, the two data are appropriately mixed and supplied to the interpolation calculation unit 35 as new data.
[0031]
The interpolation calculation unit 35 performs an interpolation calculation of the correction amount of the entire screen from the convergence data of the adjustment point as an input, and outputs the calculated convergence correction amount to the D / A converters 361 to 366 in accordance with the scanning timing. . The convergence correction amount becomes an analog signal at the D / A converters 361 to 366, but is still a step-like waveform including a harmonic component. Therefore, after the harmonic components are removed by the LPFs 371 to 376, the digital convergence circuit 22 outputs the signal.
[0032]
Thus, in one embodiment of the present invention, the provision of the mixing unit 40 enables appropriate convergence correction according to the brightness of the screen, and can minimize the deviation of convergence at any brightness.
[0033]
Next, a second embodiment of the present invention will be described with reference to FIG. The difference between the configuration of FIG. 4 and the first embodiment is that the data stored in the memory 31 is different and that the configuration of the mixing circuit 40 is different.
[0034]
That is, in FIG. 4, a set of convergence data that fits correctly on a dark screen is stored in the memory 32, while the memory 31 corresponds to a shift amount when the screen becomes bright based on a dark screen. Offset amount data is stored. Further, the detection signal data from the A / D converter 41 and the data read from the memory 31 are multiplied by a multiplier 43, and the data from the memory 32 and the output of the multiplier 43 are added by an adder 45. The output is supplied to the interpolation operation circuit 35.
[0035]
According to the above embodiment, for example, on a dark screen, the coefficient K = 0, and the offset amount is not reflected. On a bright screen, k = 1, and the offset amount from the multiplier 43 is supplied to the adder 45 and added to the convergence data on the dark screen. On a screen of intermediate brightness, an offset amount suitable for brightness is added to the convergence data of a dark screen.
[0036]
With this configuration, the same effect as that of the first embodiment can be obtained. The size of the offset value is much smaller than that of the convergence correction data itself, and the size of the memory 31 can be reduced. In the example of FIG. 4, an additional correction amount in the case of a bright change is provided as an offset based on convergence data on a dark screen. However, the reverse design, that is, convergence data on a bright screen is used as a reference. The same effect can be obtained even if an additional correction amount in the case of a dark change is provided as an offset.
[0037]
In both of the above-described embodiments, convergence data or offset data for a very bright screen (or a state where the high voltage is reduced) and a very dark screen (a state where the high voltage is raised) are stored for simplification of the description. However, convergence data at intermediate luminance may be provided as a reference. Of course, in this case, the configuration of the mixing section 40 changes.
[0038]
That is, in the embodiment of FIG. 4, for example, data subjected to convergence adjustment using a convergence adjustment pattern having appropriate luminance is stored in the memory 32. The memory 31 has a shift amount when a bright image is displayed as offset data. The A / D converter 41 has a value of zero when a convergence adjustment pattern is displayed, a positive value according to brightness when a brighter image is displayed, and a brightness value when a dark image is displayed. It is configured to output a negative value accordingly. According to the above configuration, when the convergence adjustment pattern is displayed, the data in the memory 32 is supplied to the interpolation arithmetic circuit 35 as it is, and when a bright image is displayed, the data in the memory 31 is changed according to the brightness. When the image is added and a dark image is displayed, the data in the memory 31 is subtracted according to the brightness, so that good convergence can be obtained at any brightness.
[0039]
As described above, according to the present invention, two memories are provided with convergence data of two screen brightness states, respectively, or only one of them is provided with offset data, and the mixture ratio is changed using a detection signal to change the brightness. An optimum convergence correction signal can be generated according to (high pressure). Other modifications are possible without departing from the spirit of the present invention.
[0040]
Also, the convergence adjustment of the present invention is performed by utilizing the feature of the three-tube projector, that is, the fact that the G projection tube is physically located at the center and the R and B projection tubes are located adjacent to G. May be applied only to the R and B projection tubes. In this case, the capacity of the memory can be reduced, and although the distortion including G cannot be corrected, the color shift can be corrected well.
[0041]
【The invention's effect】
As described above, according to the present invention, a convergence deviation caused by a change in brightness (or high voltage) can be accurately corrected by a rational circuit configuration.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a projection television provided with a convergence device of the present invention.
FIG. 2 is a pattern diagram illustrating convergence adjustment points.
FIG. 3 is a block diagram showing one embodiment of a digital convergence circuit of the present invention.
FIG. 4 is a block diagram showing another embodiment of the digital convergence circuit according to the present invention.
FIG. 5 is a principle diagram for explaining raster fluctuation generated by high-pressure fluctuation.
[Explanation of symbols]
11 video signal input terminal 12 selection circuit 13 adjustment pattern signal generation circuit 14 input device 15 microprocessor 16 video signal processing circuits 171-173 amplification circuits 181-183 projection tube 19 screen 20 screen synchronization Separation circuit 21 Main deflection signal generation circuit 22 Digital convergence circuits 231 to 236 Amplification circuits 241 to 243 Auxiliary deflection coil 25 Detection signal input terminal 26 High voltage generation circuit 30 Nonvolatile memories 31 and 32 Memory 34 Timing signal generation circuit 35 Interpolation operation circuit 40 Mixing circuit 41 A / D conversion circuit 42 Coefficient generation circuits 43 and 44 Multiplier 45 Adder

Claims (11)

In a convergence device in a CRT type display device,
First convergence correction data that can store convergence correction data corresponding to a plurality of adjustment points on a display screen of the display device, and is suitable when the brightness of the display screen is a predetermined bright state; A memory for respectively storing second convergence correction data suitable for a predetermined dark state;
A mixing circuit that mixes the first and second convergence correction data read from the memory in accordance with a detection signal indicating brightness of the display screen;
Using the convergence correction data from the mixing circuit, a convergence signal generation circuit that generates a convergence correction signal between the adjustment point and each adjustment point,
And a sub-deflection coil to which the convergence correction signal is supplied. The first convergence correction data is composed of a set of convergence data that is correctly matched for the brightest display screen, and the second convergence correction data is composed of a set of convergence data that is correctly matched for the darkest display screen. The convergence device according to claim 1, wherein: The mixing circuit includes an A / D conversion circuit that converts the detection signal into a coefficient value K (0 ≦ k ≦ 1), and a first multiplier that multiplies the first convergence correction data by the coefficient value K. A circuit for generating a coefficient value (1-k); a second multiplier for multiplying the second convergence correction data by the coefficient value (1-k); and the first and second multiplications 2. The convergence device according to claim 1, further comprising an adder for adding the output of the adder. In a convergence device in a CRT type display device,
First convergence correction data that can store convergence correction data corresponding to a plurality of adjustment points on a display screen of the display device and is suitable when the brightness of the display screen is in a first state; A memory for storing offset data corresponding to a shift amount of convergence when the brightness of the screen changes with reference to the first state;
An addition circuit that multiplies the offset data read from the memory by a coefficient corresponding to a detection signal representing the brightness of a display screen and adds the offset data to the first convergence correction data read from the memory; ,
Using the convergence correction data from the addition circuit, a convergence signal generation circuit that generates a convergence correction signal between the adjustment point and each adjustment point,
And a sub-deflection coil to which the convergence correction signal is supplied. 2. The convergence device according to claim 1, wherein the first convergence correction data is a set of convergence data that is correctly matched on a bright display screen or a dark screen. An A / D conversion circuit for converting the detection signal into a coefficient value K (0 ≦ k ≦ 1); a first multiplier for multiplying the offset data by the coefficient value K; 2. The convergence apparatus according to claim 1, further comprising an adder for adding the convergence correction data of one and the output of the multiplier. The convergence device according to claim 1, wherein the detection signal indicating the brightness of the display screen is a signal indicating a variation amount of an anode voltage of the CRT. The digital convergence apparatus according to claim 1, wherein the detection signal representing the brightness of the display screen is a signal obtained by integrating a video signal supplied to the CRT for a predetermined time. In a projection display device in which three projection tubes corresponding to R (red), G (green), and B (blue) are arranged in parallel,
Among the projection tubes, sub deflection coils provided at least on the projection tubes located at least outside,
Convergence correction data corresponding to a plurality of adjustment points on the display screen can be stored for each projection tube provided with the sub-deflection coil, and is suitable when the brightness of the display screen is a predetermined bright state. A memory for storing the first convergence correction data and a memory for respectively storing second convergence correction data suitable for a predetermined dark state;
A mixing circuit that mixes the first and second convergence correction data read from the memory in accordance with a detection signal indicating brightness of the display screen;
Using the convergence correction data from the mixing circuit, comprising a convergence signal generation circuit that generates a convergence correction signal between the adjustment point and each adjustment point,
A projection display device, wherein the convergence correction signal is supplied to the sub deflection coil to perform convergence correction. In a projection display device in which three projection tubes corresponding to R (red), G (green), and B (blue) are arranged in parallel,
Among the projection tubes, sub deflection coils provided at least on the projection tubes located at least outside,
Convergence correction data corresponding to a plurality of adjustment points on the display screen of the display device can be stored for each projection tube provided with the sub deflection coil, and when the brightness of the display screen is in the first state A memory for storing first convergence correction data suitable for the following, and offset data corresponding to the amount of deviation of convergence when the brightness of the screen changes based on the first state,
An addition circuit that multiplies the offset data read from the memory by a coefficient corresponding to a detection signal representing the brightness of a display screen and adds the offset data to the first convergence correction data read from the memory; ,
Using the convergence correction data from the addition circuit, a convergence signal generation circuit that generates a convergence correction signal between the adjustment point and each adjustment point,
A sub-deflection coil to which the convergence correction signal is supplied. The three projection tubes are arranged such that R and B projection tubes are arranged on both sides of the G projection tube as a center, and at least sub-deflection coils are provided for the R and B projection tubes. 11. The projection type display device according to claim 9, wherein a convergence correction signal is supplied from a convergence signal generation circuit.

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