JP2895131B2 - Automatic convergence correction device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic convergence correction device for a projection display.

[Conventional technology]

In general, in a projection display, images projected from three projection tubes corresponding to red, green, and blue (hereinafter abbreviated as R, G, and B) through a projection lens are combined on a screen to form a color image. Has formed. 3 corresponding to R, G, B
Since the projected images from the book tube enter the screen at different angles, different image distortions occur in the R, G, B images, and the R, G, B images do not match on the screen, A so-called convergence shift occurs.

Therefore, in the projection display, in order to correct the convergence deviation, a correction current having a waveform obtained by synthesizing a sawtooth wave or a parabola wave synchronized with horizontal / vertical scanning is supplied to the convergence yoke. Also,
In order to improve the correction accuracy, the correction value is stored in a digital memory, and read out in synchronization with horizontal / vertical scanning to generate a correction current having a waveform of an arbitrary shape.
Many employ a so-called digital convergence method.

By the way, in such a projection type display capable of correcting the convergence deviation, by the time the product is shipped, the correction operation is, of course, properly adjusted so that the convergence deviation does not occur. .
However, after that, due to the movement of the set, a temperature drift, a change with time, or the like, even if the correction operation is performed, a convergence deviation may occur, and the image quality may be deteriorated.

For this reason, conventionally, a photodetector is provided around the screen or in the vicinity thereof, and the detection patterns are sequentially projected by three projection tubes corresponding to R, G, and B in place of an image obtained from an image signal. There has been proposed an automatic convergence correction device for detecting a convergence shift by the photodetector for each projection tube and automatically correcting the convergence shift.

It should be noted that, as a device related to this type, for example, those described in JP-A-63-61590, JP-A-63-283383 and the like can be mentioned.

[Problems to be solved by the invention]

By the way, in recent projection displays, not only one type of image signal but also a plurality of types of image signals having different specifications, such as an image signal obtained from ordinary television broadcasting and an image signal obtained from a computer or the like, are used. Something that can be input has been developed.

In such a projection display, for example, in the case of an image signal obtained from a normal television broadcast, the image size is set so as to have an overscan portion and displayed, but the image signal obtained from a computer or the like is displayed. In this case, an image size is set so as not to have an overscan portion so that characters to be displayed are not lost. That is, the image based on the image signal is displayed with the image size set according to the specification of the image signal.

On the other hand, in such a projection type display, when the convergence deviation is corrected by using the automatic convergence correction device as described above, the correction must be performed for each type of image signal.

However, at this time, in the case of an image signal obtained from a normal television broadcast, since the image is set to an image size having an overscan portion, the image is displayed in the overscan portion even when the detection pattern is projected. By doing so, the detection pattern is applied to the photodetector, and the convergence deviation can be detected. However, in the case of an image signal obtained from a computer or the like, the image size is set to have no overscan portion. Therefore, even if the detection pattern is projected, the detection pattern does not reach the photodetector, and the convergence deviation cannot be detected.

As described above, in the case of an image signal of a specification that is set and displayed with an image size that does not have an overscan portion, the detection pattern is applied so that the detection pattern is applied to the position where the photodetector is provided. And the convergence deviation cannot be detected using the detection pattern and the photodetector.

An object of the present invention is to provide a specification of an input image signal.
It is an object of the present invention to provide an automatic convergence correction device capable of detecting a convergence deviation using a detection pattern and a photodetector regardless of the image size.

[Means for solving the problem]

In order to achieve the above object, in the present invention, a control circuit and a deflection yoke attached to each projection tube are driven to scan each image, and the image size is set by the control circuit. A deflecting circuit for controlling the image size, and a correction signal according to the convergence correction amount set by the control circuit, and driving the convergence yokes respectively attached to the respective projection tubes by the correction signal, and A convergence circuit for correcting the convergence deviation of each image of
A pattern generation circuit, a signal switching circuit, and a photodetector provided around or near the screen, wherein the control circuit performs a convergence automatic correction operation by the detection pattern generation circuit. A signal is generated and, by the signal switching circuit, the generated detection pattern signal is sequentially input to each projection tube in place of the image signal, whereby the detection pattern is sequentially projected from each projection tube onto the screen. The image size set in the deflection circuit is changed so that the detection pattern is projected on the photodetector, and the convergence correction amount set in the convergence circuit is corrected in accordance with the change amount, and the light detection is performed. Based on the amount of deviation of the detection pattern from the reference position detected by the detector, And to control the convergence correction amount to be set in the convergence circuit as crucible becomes zero.

In addition, the control circuit generates a detection pattern signal by the detection pattern generation circuit as a detection pattern initial setting operation separately from the convergence automatic correction operation, and converts the detection pattern signal generated by the signal switching circuit into the image. By causing a signal to be input to at least one of the projection tubes instead of a signal, the detection pattern is projected from the projection tube onto the screen, so that the detection pattern is projected on the photodetector. While changing the image size set in the deflection circuit,
The detection pattern is projected by controlling the detection pattern generation circuit so that the deviation amount is substantially zero based on the deviation amount of the detection pattern from the reference position detected by the photodetector. The position is controlled.

[Action]

At the time of the automatic convergence correction operation, the control circuit sets the deflection circuit so that the detection pattern is projected on the photodetector regardless of the image size set according to the specification of the input image signal. Since the image size is changed and set to a predetermined size,
Convergence deviation can be detected, and automatic convergence correction can be performed. Further, when the control circuit changes the image size, the control circuit corrects the convergence correction amount set in the convergence circuit in accordance with the change amount, so that the correction accuracy of the automatic convergence correction does not deteriorate.

In addition, when the user moves the position of the image, the position of the detection pattern also moves accordingly, and when the convergence automatic correction operation is performed, the detection pattern is not projected on the photodetector and the convergence deviation cannot be detected. Even when the control circuit controls the position where the detection pattern is projected by controlling the detection pattern generation circuit, thereafter, when performing the automatic convergence correction operation, the detection pattern is placed on the photodetector. Since the image can be projected, the convergence deviation can be always detected, and a normal convergence automatic correction operation can be performed.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a projection display provided with an automatic convergence correction device as one embodiment of the present invention.

In FIG. 1, 1R, 1G, 1B are R, G, B video signal input terminals, 2H, 2V are horizontal and vertical synchronizing signal input terminals, 3, 4 are signal switching circuits for video circuits, 5R, 5G , 5B are video circuits corresponding to R, G, B, 6R, 6G, 6B are projection tubes corresponding to R, G, B, 7
Is a deflection yoke (hereinafter abbreviated as DY); 8 is a deflection circuit; 9 is a convergence yoke (hereinafter abbreviated as CY); 10 is a convergence circuit; 11 is a screen; Provided photodetector,
13 is a detection pattern generation circuit, 14 is a detection voltage input from the photodetector 12, and controls the convergence automatic correction device which controls the convergence circuit 10, the deflection circuit 8, the signal switching circuits 3 and 4, and the detection pattern generation circuit 13. Circuit.

In FIG. 1, the components other than the signal switching circuits 3 and 4, the photodetector 12, the detection pattern generation circuit 13, and the control circuit 14 are the same as those of the conventional projection type display, so that the description thereof will be omitted, and the convergence automatic display according to the present invention will be omitted. About the correction operation, the second
This will be described with reference to the flowchart in FIG.

During the automatic convergence correction operation, the control circuit
14 switches the inputs of the video circuits 5R, 5G, 5B to the signal switching circuit 4 by the signal switching circuit 3 in order to project the detection pattern.

Next, the control circuit 14 controls the deflecting circuit 8 so that the detection pattern is projected on the photodetector 12 irrespective of the image size set according to the specification of the image signal input up to that time. Then, the image size is set to a predetermined image size.

Next, the control circuit 14 changes the convergence correction amount required to reduce the convergence deviation to zero due to the change in the image size, so that the convergence correction amount preset in the convergence circuit 10 according to the change in the image size. To correct.

Next, the control circuit 14 causes the signal switching circuit 4 to input the detection pattern signal to the video circuit of the color to be corrected and perform the correction operation for each of the R, G, and B colors. Is set so that the circuit portion corresponding to the color to be corrected is controlled.

As described above, since the detection pattern of the color to be corrected is projected on the photodetector 12, the control circuit 14
Output the detection voltage.

FIG. 3 shows the characteristics of the photodetector 12 including a semiconductor position detecting element and the like.

As is clear from FIG. 3, a detection voltage proportional to the position of the detection pattern is obtained. Here, a substantially center of the photodetector 12 is set as a reference position, and a detection voltage when the detection pattern comes to the reference position is set as a reference detection voltage. That is, as shown in FIG. 3, the difference between the reference detection voltage and the output detection voltage is the amount of deviation of the detection pattern from the reference position. Therefore, if the control circuit 14 controls the convergence correction amount set in the convergence circuit 10 so that the difference between the detection voltage from the photodetector 12 and the reference detection voltage becomes zero,
The detection pattern comes to coincide with the reference position.

When the correction operation for a certain color is completed, the signal switching circuit 4 and the like are switched to perform the same correction operation for the other colors. Then, when the correction of the three colors R, G, and B is completed, the three detection patterns R, G, and B coincide with the reference position, so that there is no convergence deviation and the convergence is in a state.

After the correction of the three colors R, G, and B is completed, the control circuit 14 controls the deflection circuit 8 to reduce the image size to an image size corresponding to the specification of the original input image signal. At the same time, the convergence correction amount set in the convergence circuit 10 is corrected again in accordance with the change in the image size.

Thereafter, the control circuit 14 switches the input of the video circuits 5R, 5G, 5B to the image signal side by the signal switching circuit 3, and causes the video circuits 5R, 5G, 5B to input the image signals of R, G, B, Set to the operating state.

As described above, according to the present embodiment, during the automatic convergence correction operation, the detection pattern is projected on the photodetector 12 regardless of the image size set according to the specification of the input image signal. Since the image size is set to a predetermined size, the convergence deviation can be detected, and the convergence automatic correction can be performed. Further, since the convergence correction amount set in the convergence circuit 10 is corrected in accordance with the change in the image size, the correction accuracy of the convergence automatic correction does not deteriorate.

By the way, in a projection type display capable of inputting a plurality of types of image signals, the position of the displayed image is
Some can be moved to any position on the screen 11 by the user.

In such a projection display, when the user moves the position of the image, the position of the detection pattern projected during the automatic convergence operation is also moved accordingly, so during the automatic convergence operation, There is a problem that the detection pattern is not projected on the photodetector 12, and the convergence deviation cannot be detected.

Therefore, in this embodiment, when the user moves the position of the image, the following initial setting operation of the detection pattern is performed at least once before performing the automatic convergence correction operation.

When the user moves the position of the image as described above, it is necessary to move the image in a state where the convergence deviation is corrected in advance so that the subsequent automatic convergence correction operation does not malfunction.

Next, the initial setting operation of the detection pattern will be described with reference to the flowchart of FIG.

The initial setting operation of the detection pattern is almost the same as the automatic convergence correction operation shown in FIG. 3, but in the automatic convergence correction operation, the control circuit 14 sets the convergence correction in the convergence circuit 10 so that the convergence deviation becomes zero. The difference is that the amount is controlled, but in the initial setting operation, the control circuit 14 controls the detection pattern generation circuit 13 to adjust the position of the detection pattern so that the convergence deviation becomes zero.

Thus, by adjusting the position of the detection pattern, the detection pattern can be projected on the photodetector 12.

In the initial setting operation of the detection pattern, it is not necessary to perform the above adjustment for each of R, G, and B.
You only have to do it once. However, if high accuracy is required such that a difference in focus with respect to R, G, B or a difference in sensitivity of the photodetector 12 becomes a problem, it is necessary to perform the above adjustment for each of R, G, B. There is.

As described above, according to the present embodiment, when the user moves the position of the image, the detection pattern is initialized by performing the above-described initial setting operation of the detection pattern, and thereafter, when performing the convergence automatic correction operation, the detection pattern is changed. Since the image can be projected on the photodetector 12, the convergence deviation can be always detected, and a normal automatic convergence correction operation can be performed.

Next, one specific example of the main circuit in FIG. 1 is shown in FIG.

5, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

In addition, reference numeral 20 denotes a switching circuit for switching which output of the photodetector 12 is selected, and reference numeral 21 denotes an A / D for converting a detection voltage from the photodetector 12 into analog / digital (hereinafter abbreviated as A / D).
Converter. 22 is an arithmetic processing unit (hereinafter referred to as CP
23, memory 24, address counter 25, digital / analog (hereinafter abbreviated as D / A) converter 2
6. A digital convergence circuit composed of a low-pass filter for waveform interpolation (hereinafter abbreviated as LPF) 27 and a control panel 28. 29 is an analog convergence circuit.

Reference numerals 30, 31, and 32 denote horizontal control voltage generators 33 each including a latched D / A converter, similarly vertical control voltage generators 34, and horizontal voltage control convergence correction circuits.
35, a convergence drift correction circuit for R, G, B composed of a vertical voltage control convergence correction circuit 36; Reference numerals 37, 38, and 39 denote addition circuits, reference numeral 40 denotes a horizontal size control voltage generation circuit including a latched D / A converter, and reference numeral 41 denotes a vertical size control voltage generation circuit.

1, the range surrounded by the dashed line in FIG. 5 corresponds to the convergence circuit 10 and the control circuit 14 shown in FIG. 1, and most of them correspond to the convergence circuit 10. In particular, the digital convergence circuit 22 and the analog convergence circuit 29 are conventional. The CPU 23 of the conventional digital convergence circuit 22 also serves as the control circuit 14 shown in FIG.

In FIG. 5, since four photodetectors 12 are used in each of the horizontal and vertical directions, four types of convergence correction components can be detected in each of the horizontal and vertical directions. And, in the horizontal and vertical directions, two are respectively provided at the center and both ends of the screen out of the four, so that static, skew, size, and linearity can be detected as four types of convergence correction components. Since the number of the photodetectors 12 is the same as the number of convergence correction components in the horizontal and vertical directions, the number of the photodetectors 12 is not limited to eight but may be the same as the number of necessary correction components.

 Hereinafter, the operation will be described.

During normal operation, the size control voltage generation circuits 40, 4
In 1, desired data is latched by the CPU 23 in order to control the deflection circuit 8 so as to have an image size according to the specification of an input image signal. In addition, the control voltage generation circuits 33 and 34 are also set by the CPU 23 to set a convergence correction amount according to the specification of the input image signal.
Desired data is latched.

Then, the digital convergence circuit 22 is operated by the CPU 23 and the analog convergence circuit
29 and the convergence drift correction circuits 30, 31, and 32 also operate to correct convergence deviation.

Then, even if the above-described correction operation is performed due to the movement of the set, the temperature drift, the change with the passage of time, or the like, when the convergence deviation occurs, the convergence automatic correction is performed in accordance with an instruction from the control panel 28.

At the time of automatic convergence correction, first
Switches the signal switching circuit 3 shown in FIG.
In order to control the deflection circuit 8 so that the detection pattern has an image size that is projected on the photodetector 12, predetermined data is used instead of the data latched by the size control voltage generation circuits 40 and 41. Latch. Next, CPU23
The control voltage generation circuit 3 is used to correct the set convergence correction amount in accordance with the change in the image size described above.
Correct the above data latched at 3,34.

Next, the CPU 23 switches the signal switching circuit 4 to input the detection pattern signal to the video circuit of the color to be corrected, and from the convergence drift correction circuits 30, 31, and 32, the circuit corresponding to the color to be corrected. Set. Next, CP
U23 controls the switching circuit 20 to sequentially switch the detection voltage output from each photodetector 12, while the A / D converter 2
A / D conversion is performed in 1 and the obtained data is taken in to calculate the shift amount. Then, the CPU 23 changes the aforementioned data latched by the control voltage generation circuits 33 and 34 of the set convergence drift correction circuit so that the obtained deviation amount becomes zero, and changes the set convergence correction amount. .

That is, the control voltage generation circuits 33 and 34 convert the latched data into a DC voltage and use the DC data as a control voltage to control the voltage control convergence correction circuits 35 and 36. As a result, the convergence correction amount changes.

Here, a specific example of the voltage control convergence correction circuit 35 in FIG. 5 is shown in FIG.

In FIG. 6, 50 is a static control voltage input terminal, 51 is a skew control voltage input terminal, 52 is a sawtooth wave input terminal for skew correction, 53 is a size control voltage input terminal,
54 is a sawtooth wave input terminal for size correction, 55 is a linearity control voltage input terminal, 56 is a parabolic wave input terminal for linearity correction, 57 is a multiplication circuit, and 58 is an addition circuit.

The static control voltage input terminal 50, the skew control voltage input terminal 51, the size control voltage input terminal 53, and the linearity control voltage input terminal 55 have a static control voltage and a skew control voltage which are current voltages output from the control voltage generation circuit 33. , A size control voltage, and a linearity control voltage, respectively, and voltage control is applied to a sawtooth input terminal 52 for skew correction, a sawtooth input terminal 54 for size correction, and a parabolic wave input terminal 56 for linearity correction, respectively. The vertical cycle saw voltage, the horizontal cycle saw voltage, and the horizontal cycle parabola voltage generated in the convergence correction circuit 35 are input.

The control voltages other than the static control voltage are multiplied by a multiplying circuit 57 by a vertical period sawtooth voltage, a horizontal period sawtooth voltage, and a horizontal period parabola wave voltage, respectively. Therefore, the multiplying circuit 57 obtains a sawtooth voltage having a vertical cycle, a sawtooth voltage having a horizontal cycle, and a parabolic wave voltage having a horizontal cycle having amplitudes corresponding to the magnitudes of the respective control voltages.

The voltage thus obtained, including the static control voltage, is then added by the adding circuit 58 and output as a horizontal convergence correction voltage. Therefore, by adjusting each control voltage, a convergence correction voltage having a desired waveform can be obtained.

That is, the CPU 23 changes the above-mentioned data latched by the control voltage generation circuits 33 and 34 of the convergence drift correction circuit to obtain a convergence correction voltage having a desired waveform, and the deviation of the detection pattern from the reference position. The quantity can be zero.

As described above, when the correction is completed for the R, G, and B colors, the CPU 23 again controls the deflection circuit 8 to control the deflection circuit 8 to have an image size according to the specification of the input image signal. Desired data is latched in place of the data latched by the voltage generation circuits 40 and 41. Next, the CPU 23 corrects the changed data latched by the control voltage generation circuits 33 and 34 in order to correct the convergence correction amount again in accordance with the change in the image size. Then, the CPU 23 switches the signal switching circuit 3 shown in FIG. 1, and as a result, the automatic convergence correction operation ends and returns to the normal operation again.

Next, when the user moves the position of the image in a state where the convergence deviation has been corrected, an initial setting operation of the detection pattern is performed in accordance with an instruction from the control panel 28.

The initial setting operation of the detection pattern is almost the same as the automatic convergence correction operation described above, but the CPU 23 operates the detection pattern generation circuit 1 so that the convergence deviation becomes zero.
3 differs from the automatic convergence correction operation in that the data input to 3 is changed to adjust the position of the detection pattern and that the adjustment is performed only for G.

As described above, according to the specific example shown in FIG.
CPU 23 of conventional digital convergence circuit 22
Is also used as the control circuit 14 shown in FIG.
The circuit can be simplified.

Next, another specific example of the main circuit in FIG. 1 is shown in FIG.

7, the same components as those in FIGS. 1 and 5 are denoted by the same reference numerals, and the description thereof will be omitted.

In this specific example, the analog convergence circuits 29, R, G, and B convergence drift correction circuits 30, 31, and 32 shown in the specific example of FIG. The convergence circuit 10 is composed of only the digital convergence circuit 22 and performs all convergence correction operations digitally. Accordingly, although the capacity of the memory 24 is increased as compared with the specific example of FIG. 5, the circuit scale is simplified because other circuits are deleted accordingly.

Also in this specific example, as in the specific example of FIG. 5, the CPU 23 of the digital convergence circuit 22 also serves as the control circuit 14 shown in FIG.

As described above, in this specific example, the convergence automatic correction operation and the initial setting operation of the detection pattern, which were performed analogously in the specific example of FIG. 5, are only performed digitally. The same effect as that of the specific example of FIG. 5 can be obtained.

〔The invention's effect〕

As described above, according to the present invention, at the time of the automatic convergence correction operation, the detection pattern is projected on the photodetector regardless of the image size set according to the specification of the input image signal. Since the size is set to a predetermined size, a convergence shift can be detected, and convergence automatic correction can be performed. In addition, since the convergence correction amount set in the convergence circuit is corrected according to the change in the image size, the correction accuracy of the automatic convergence correction does not deteriorate.

In addition, when the user moves the position of the image, by performing the initial setting operation of the detection pattern, the detection pattern can be projected on the photodetector when the automatic convergence correction operation is performed thereafter. A convergence deviation can be detected, and a normal convergence automatic correction operation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a projection type display provided with an automatic convergence correcting device as one embodiment of the present invention, FIG. 2 is a flowchart showing a flow of an automatic convergence correcting operation in FIG. 3 is a characteristic diagram showing characteristics of the photodetector in FIG. 1, FIG. 4 is a flowchart showing a flow of an initial setting operation of a detection pattern in FIG. 1, and FIG. 5 is a specific example of a main circuit in FIG. FIG. 6 is a block diagram showing one specific example of the voltage control convergence correction circuit in FIG. 5, and FIG. 7 is a block diagram showing another specific example of the main circuit in FIG. . Description of reference numerals 3,4 ... signal switching circuit, 5 ... video circuit, 6 ... projection tube, 8 ... deflection circuit, 10 ... convergence circuit, 11 ...
... Screen, 12 ... Photodetector, 13 ... Detection pattern generation circuit, 14 ... Control circuit, 21 ... A / D converter, 22 ... Digital convergence circuit, 23 ... CPU, 29 ... Analog convergence Circuit, 30, 31, 32: Convergence drift correction circuit, 33, 34: Control voltage generation circuit, 35, 36
... voltage control convergence correction circuit, 37, 38, 39 ... adder, 40, 41 ... size control voltage generation circuit, 57 ... multiplier, 58 ... adder.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahisa Tsukahara 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi Video Engineering Co., Ltd. (72) Kenichi Fukiage 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Video Engineering (56) References JP-A-63-61590 (JP, A) JP-A-63-283383 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 9/31 H04N 9/28 H04N 17/00

Claims (6)

(57) [Claims] An image signal corresponding to red, green, and blue is input to each of red, green, and blue projection tubes, and red, green, and blue images are respectively output from the respective projection tubes on a screen. And superimpose each image on the screen,
In a projection display that displays a color image, a control circuit and a deflection yoke attached to each projection tube are driven to scan each image, and the image size is set by the control circuit. And a deflection circuit for controlling the convergence correction amount set by the control circuit to generate a correction signal. The correction signal drives a convergence yoke attached to each of the projection tubes, thereby forming each image on the screen. A convergence circuit for correcting the convergence deviation, a pattern generation circuit, a signal switching circuit, and a photodetector provided around or around the screen, and the control circuit performs a convergence automatic correction operation. ,
The detection pattern generation circuit generates a detection pattern signal, and the signal switching circuit sequentially inputs the generated detection pattern signal to each projection tube in place of the image signal, so that the detection pattern is output from each projection tube. The image size set in the deflection circuit is changed so that the detection pattern is projected on the photodetector, and the reference of the detection pattern detected by the photodetector is displayed. An automatic convergence correction device, wherein a convergence correction amount set in the convergence circuit is controlled based on a deviation amount from a position so that the deviation amount becomes substantially zero. 2. The convergence correction device according to claim 1, wherein the control circuit sets the convergence correction amount in the convergence circuit in accordance with the change amount when changing the image size set in the deflection circuit. Automatic convergence correction device, wherein 3. The automatic convergence correction apparatus according to claim 1, wherein said control circuit outputs a detection pattern signal by said detection pattern generation circuit as a detection pattern initial setting operation separately from said automatic convergence correction operation. Generating, by the signal switching circuit, by inputting the generated detection pattern signal to at least one of the projection tubes instead of the image signal, to project the detection pattern from the projection tube to the screen,
At that time, the image size set in the deflection circuit is changed so that the detection pattern is projected on the photodetector, and the deviation amount of the detection pattern detected by the photodetector from a reference position is reduced. An automatic convergence correction device for controlling the position where the detection pattern is projected by controlling the detection pattern generation circuit so that the deviation amount becomes substantially zero on the basis of the deviation amount. 4. The automatic convergence correction apparatus according to claim 3, wherein the detection pattern initial setting operation by the control circuit is performed in a state where there is no convergence deviation of each image on the screen. Automatic convergence correction device. 5. An automatic convergence correction apparatus according to claim 1, wherein said convergence circuit digitally creates a part or all of said correction signal. 6. The automatic convergence correction apparatus according to claim 5, wherein said control circuit is included in said convergence circuit.