KR100560894B1 - Method and apparatus for compensating auto convergence of projection TV - Google Patents

Abstract

An apparatus and method for auto-convergence correction of projection TV, comprising: a screen for displaying R, G, and B video signals; and a first and a second for detecting a pattern mounted on a predetermined area of the screen and displayed on the screen. In the projection TV having the first to eighth detection unit equipped with an optical sensor, a predetermined size for measuring the distance between the R, G, B pattern displayed on the screen and the first and second optical sensors A test pattern generator for generating an OSD test pattern, a distance value between a pattern generated by the test pattern generator for each of R, G, and B and movement of the pattern generated by the test pattern generator; Memory for storing the detection results of the first and second optical sensors mounted on the first to eighth detection unit, and the test pattern is generated when auto convergence is executed And a microcomputer for controlling the test pattern to be changed in size and start position by detecting a distance between the pattern generated by the unit and the distance between the first and second optical sensors and correcting the difference between the distance stored in the memory. It is configured to, and as the auto convergence is performed more accurately, there is an effect that can provide a higher quality screen.

Projection TV / Auto Convergence

Description

Method and apparatus for compensating auto convergence of projection TV

 1 is a block diagram showing an auto convergence adjustment device of a projection TV according to the prior art.

2 is a diagram illustrating the detection criteria according to the movement of the measurement pattern

3 is a waveform diagram illustrating an output waveform of a comparator according to an output waveform of the amplifier illustrated in FIG. 1.

Figure 4 is a block diagram showing an auto convergence adjustment device of the projection TV according to the present invention

FIG. 5 is a diagram illustrating reference data when executing the auto convergence factory mode stored in FIG. 4. FIG.

6 is a view showing the arrangement of the first to eighth detection unit according to the present invention and the method of detecting a side view pattern

7 is a diagram illustrating detection criteria according to the movement of a measurement pattern.

8 is a flow chart showing a first embodiment of the auto-convergence method of projection TV according to the present invention.

9 is a flow chart showing a second embodiment of the auto-convergence method of the projection TV according to the present invention.

Explanation of symbols for main parts of the drawings

110: tuner 111: IF

112: audio processing unit 113: image processing unit

114: H / V deflection portion 115: microcomputer

116: test pattern generator

117: memory (EEPROM) 118: digital convergence unit

119: power amplifier 120: switching unit

121 to 123: image amplification part 124 to 126: deflection part

127-129, 130-132: horizontal / vertical convergence yoke

133-135: PRT 136: screen

136a to 136f: first to eighth sensing units

137: comparison unit 138: inverter

139: D F / F

The present invention relates to an image display device, and more particularly, to an apparatus and method for auto-convergence of a projection TV that prevents the convergence from being changed due to external factors when performing the auto-convergence function in the projection TV so that more efficient auto-convergence can be performed. It is about.

In general, video display devices are being introduced to consumers in various forms, starting with small models such as 14-inch analog receivers and projection TVs of 60 inches or more.

Projection TV is a device that displays images on the screen by projecting the colors of R, G, and B on the screen using respective CRTs.The quality of the projection TV is W / U (White Uniformity), B / U (Bright). It consists of various items such as Uniformity, Convergence, Focus, and Distortion.

Here, convergence means that the R (Red), G (Green), and B (Blue) beams emitted by the electron gun are collected at a point on the screen by the magnetic field of the deflection yoke, but the influence of the abnormality or the magnetic field of the deflection yoke If the beam is not deflected as desired, mis-convergence occurs and color shift occurs on the screen.

In other words, three beams of R, G, and B must be gathered exactly at one point to become white. When the image is miss-converged, abnormally colored lines such as R, G, and B will be displayed next to the white line. It acts as a factor to decrease.

Therefore, in order to show white color, the light projected from each C, R, G, and B tubes should be collected in one place. Here, the convergence of R, G, and B light in one place is called auto convergence. As the digital TV broadcasting starts, a projection TV is in the spotlight as a display that meets the needs of a large screen.

Such auto convergence generates a specific pattern on the screen, and uses the optical sensor to determine the degree of convergence and then corrects it.

Hereinafter, with reference to the accompanying drawings illustrating a convergence adjustment apparatus of the projection TV according to the prior art.

1 is a block diagram showing the configuration of the convergence adjustment device of the projection TV according to the prior art, Figure 2 is a view showing a detection method of the optical sensor according to the movement of the measurement pattern, Figure 3 is a light according to the movement of the measurement pattern This is a waveform diagram showing the output waveform of the sensor.

As shown in FIG. 1, the convergence adjusting apparatus of the projection TV according to the related art includes a screen 10 for displaying an image signal and first to eighth sensing units mounted on a predetermined area of the screen 10. 11 to 18, an amplification unit 20 that receives the sensed values detected through the first to eighth sensing units 11 to 18 and amplifies and outputs the amplified by a predetermined multiple, and amplified by the amplifying unit 20. The comparison unit 30 receives and compares the amplification value to the inverting (-) terminal and the non-inverting (+) terminal as preset, and the AND gate 40 receiving the output value of the comparing unit 30 and performing an AND operation. ), An inverter 50 for inverting the output of the AND gate 40, a D flip-flop 60 for receiving and latching an output value of the inverter 50, and the D flip-flop 60. Do not output the control signal to receive the latched data and adjust the convergence It consists of the ICCOM 70.

In the first to eighth sensing units 11 to 18, the first, third, fifth, and seventh sensing units 11, 13, 15, and 17 are formed at the centers of the four sides of the screen 10. The second, fourth, sixth and eighth detectors 12, 14, 16 and 18 are located at the four corners of the screen 10. In addition, the first to fourth sensing units 11 to 14 are divided into a first group, and the fifth to eighth sensing units 15 to 18 are divided into a second group, and the first to eighth sensing units ( 11 to 18 include a plurality of first and second photosensors A and B, as shown in FIG.

In addition, the amplifying unit 20 is a first to receive and amplify the sensed values respectively sensed by the first and second optical sensors (A) (B) in the first to fourth sensing units (11 to 14) A second amplifying unit 21 and a second amplifying unit for receiving and amplifying sensing values sensed through the first and second optical sensors A and B by the fifth to eighth sensing units 15 to 18, respectively; It consists of 22.

The first amplifier 21 may include a first amplifier 21a for receiving and amplifying a value detected by the first optical sensor A from the first to fourth detectors 11 to 14. The first to fourth sensing units 11 to 14 are configured to receive and amplify a sensing value sensed through the second optical sensor B to amplify the second amplifier 21b. The second amplifier 22 is a third amplifier (22a) for receiving and amplifying the sensed value detected by the first optical sensor (A) in the fifth to eighth sensing unit (15 to 18), The fifth to eighth sensing units 15 to 18 may include a fourth amplifier 22b that receives and amplifies a sensing value detected through the second optical sensor B.

The comparator 30 may include a first comparator 31 configured to receive and compare output values of the first and second amplifiers 21a and 21b through inverted (-) and non-inverted (+) terminals, respectively, And a second comparator 32 that receives the output values of the third and fourth amplifiers 22a and 22b through the inverting (-) and non-inverting (+) terminals, respectively, and compares them.

Referring to the operation of the automatic convergence adjustment device of the projection TV according to the prior art configured as described above are as follows.

When the user selects the auto convergence adjustment mode, the first to eighth detection units 11 to 18 detect the position of the pattern generated for the convergence adjustment, and the first to eighth detection units 11 to 18. ) And the detected value detected through the first optical sensor A is input to the second and fourth amplifiers 21b and 22b, and the detected value detected through the second optical sensor B is the first and the second It is input to the three amplifiers 21a and 22a and amplified by twice as much as the amplification degree of the second and fourth amplifiers 21b and 22b and output.

The amplified value b1 amplified by the first amplifier 21a is input to the inverting (−) terminal of the first comparator 31 and amplified value a1 amplified by the second amplifier 21b. Is input to the non-inverting (-) terminal of the first comparator 31 and outputs a comparison value c1. The amplified value b2 amplified by the third amplifier 22a is input to the inverting (−) terminal of the second comparator 32 and amplified by the fourth amplifier 22b. Is input to the non-inverting (+) terminal of the second comparator 32 to output a comparison value c2.

The output values of the first and second comparators 31 and 32 are inputted from the AND gate 40 to the inverter 50, and the values inverted through the inverter 50 are converted to the D flip-flop ( 60 is inputted and latched to enter the input of the microcomputer 70.

Herein, the sensing method according to the movement of the measurement pattern through the first to eighth sensing units 11 to 18 will be described with reference to FIGS. 2 and 3.

First, when the measurement pattern is red (even when green or blue) is moved downward for the pattern, it can be described through the detection process of the third sensor (13). First, as shown in FIG. 2, when the pattern is at the preset first sensing position t1, since the pattern does not overlap with both the first optical sensor A and the second optical sensor B, light is not detected. As shown in FIG. 3, it can be seen that a low signal is also output as a low signal is applied to both the first and second amplifiers 21a and 21b.

In addition, a low signal output from the first and second amplifiers 21a and 21b is input to the non-inverting (+) and inverting (-) terminals of the first comparator 31, respectively. The one comparator 31 outputs a high signal. This is because a slight pull-up resistor is connected to the non-inverting (+) terminal of the first comparator 31.

As shown in FIG. 2, when the pattern is at the second detection position t2, the first optical sensor A overlaps about 1/2 of the pattern, and the second optical sensor B is still It can be seen that the light is not detected because the patterns do not overlap. In this case, since the output value of the second amplifier 21b is larger than the output value of the first amplifier 21a, the first comparator 31 continues to output a high signal.

In addition, as shown in FIG. 2, when the pattern is at the third detection position t3, the first optical sensor A overlaps the pattern, and the second optical sensor B overlaps about 1/2. The first amplifier 21a in which the output value of the second amplifier 21b, which receives the detection value of the first optical sensor A, receives the detection value of the second optical sensor B, is an overlapping state. Will be twice the output of (A = 2B).

However, since the amplification degree of the first amplifier 21a is twice as large as that of the second amplifier 21b, the output values of the first amplifier 21a and the second amplifier 21b are the same, and this is input. The output value of the received first comparator 31 outputs a low signal from thereafter.

In this manner, a signal is also output from the second comparator 32, and outputs of the first and second comparators 31 and 32 are calculated by being inputted to the inverter 50 and inverted. A high signal is outputted, and the signal is inputted to the clock of the D flip-flop 60 to latch data, and a high signal is inputted to the microcomputer 70.

The microcomputer 70 determines that the position of the pattern is the third set position t3 when the port connected to the microcomputer 70 goes from low to high, and thus the initial stage of the pattern is determined. The distance from the position to the third set position t3 is measured to determine how far the convergence is, and the correction control signal is output accordingly.

As described above, the automatic convergence adjustment device of the projection TV according to the prior art has the following problems.

First, since the starting point is fixed when the auto-convergence function is executed, there is no way to detect and correct the case of severe optical and instrument deviations, which causes an error of the auto-convergence function itself.

Second, there was a case where the function did not work due to lack of design margin for the geomagnetic field and convergence misalignment during use.

Third, the auto-convergence function does not run normally, causing deterioration of image quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when the auto convergence function is performed, the auto convergence of the projection TV enables the auto convergence to be executed in a more optimal state after varying the starting point and the pattern size according to the respective optics and instruments. Its purpose is to provide a calibration device and method.

In order to achieve the above object, the apparatus for auto-convergence correction of a projection TV according to the present invention includes a screen for displaying R, G, and B video signals, and a pattern mounted on a predetermined area of the screen to detect a pattern displayed on the screen. In the projection TV having the first to eighth detection unit equipped with the first and second optical sensors for the display, the distance between the pattern of each of the R, G, B displayed on the screen and the first and second optical sensors A test pattern generator for generating an OSD test pattern having a predetermined size for measurement, and a pattern of each of R, G, and B generated by the test pattern generator for each of R, G, and B and displayed on the screen; A first unit mounted to the first to eighth sensing units according to a distance value from the first to eighth sensing units and a movement of the pattern generated by the test pattern generating unit; And a memory for storing the detection result of the second optical sensor, and a microcomputer for controlling the current size and start position of the pattern to be changed based on a distance stored in the memory when auto convergence is executed. It has its features.

In order to achieve the above object, an automatic convergence correction method of a projection TV according to the present invention includes a screen for displaying R, G, and B video signals, and R, G, and B displayed on the screen, respectively. A test pattern generator for generating an OSD test pattern having a predetermined size to measure a distance between each of the R, G, and B patterns and the first to eighth sensing units, and mounted on a predetermined area of the screen; In the method of auto-convergence adjustment of the projection TV having the first to eighth sensors and memory equipped with the first and second optical sensors for detecting the displayed pattern, when the user selects the auto-convergence factory measurement mode, the test is performed. To determine the distance between the pattern generated by the pattern generator and the first and second optical sensors mounted on the first to eighth sensing units And adjusting the size of the pattern generated by the test pattern generator or the start position of the pattern to be displayed on the screen according to the determined distance.

Hereinafter, the auto-convergence correction apparatus and method of the projection TV according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a block diagram showing an auto convergence correction apparatus of a projection TV according to the present invention, FIG. 5 is a view showing a factory auto convergence execution screen, and FIG. 6 is a layout of the first to eighth sensing units shown in FIG. 7 and 8 are flowcharts illustrating a method for auto-convergence correction of a projection TV according to the present invention.

As shown in FIG. 4, the apparatus for auto-converging correction of projection TV according to the present invention includes a tuner 110 for tuning a broadcast signal received from an antenna, and an intermediate frequency component among the broadcast signals tuned through the tuner 110. IF unit 111 for demodulating the audio signal, and a voice processing unit 112 for processing the audio signal demodulated in the IF unit 111 into a signal output through a speaker (not shown), and demodulation in the IF unit 111. The image processing unit 113 for processing the image signal as a displayable signal, and the output signal of the image processing unit 113 is selected through the switching unit 120, the image amplification unit 121 to 123 receives and amplifies and deflects it. And a deflector 124 to 126, a screen 136 for displaying an image signal through the image amplifiers 121 to 123 and a deflector 124 to 126, and a test pattern for adjusting convergence. Test pattern generation unit (1 16), a memory 117 for storing reference data for convergence adjustment, and a predetermined area of the screen 136 for detecting a position of a pattern generated by the test pattern generator 116 when auto convergence is selected. The first to eighth sensing units 136a to 136f mounted on the control unit and the first to eighth sensing units 136a to 136f when selecting a control signal and auto convergence for overall system operation according to a user's request. The microcomputer 115 controls the size or start position of the pattern generated by the test pattern generator 116 to be changed according to the detected value.

In addition, a digital convergence unit 118 for generating a cross pattern according to the control signal of the microcomputer 115, a power amplifier 119 for amplifying the output of the digital convergence unit 118, and the image processor 113. A switch 120 for selectively outputting an output signal of the power amplifier), a signal of the power amplifier 119, and an output of the test pattern generator 116, and a task generated by the test pattern generator 116. When a pattern moves the first to eighth sensing units 136a to 136f, the first and second sensing units 136a to 136f constitute the first and second optical sensors A and B to sense the pattern. After receiving the sensed value to compare the comparison unit 137, the inverter 138 for inverting the output of the comparison unit 137 and the output of the inverter 138 as a clock value and latch the data It further comprises a D flip-flop (F / F) 139 for input to the microcomputer 115 .

In addition, horizontal / vertical convergence yokes 127 to 129 for correcting misconvergence generated at the outputs of the image amplifiers 121 to 123 and the deflectors 124 to 126 and the output of the horizontal and vertical deflectors 112. 130 to 132, and PRTs 133 to 135 for processing the R, G, and B video signals inputted according to the output of the horizontal / vertical deflection unit 114 to be displayed on the screen 136.

Referring to the operation of the automatic convergence correction device of the projection TV according to the present invention configured as described above are as follows.

First, when an image signal is output through the tuner 110, and the image signal tuned by the image processor 113 is processed, the switching unit 120 performs the image processing unit according to a control signal of the microcomputer 115. The image signal processed at 113 is amplified by the image amplifiers 121 to 123 through the switching unit 120, and the image is displayed on the screen 136 through the PRTs 133 to 135.

The horizontal / vertical deflection unit 114 applies a horizontal / vertical deflection current to the PRTs 133 to 135, and corrects the image inconsistency because the PRTs 133 to 135 have three R, G, and B points. To this end, current corrected to match three R, G, and B images in the horizontal / vertical convergence yokes 127 to 129 and 130 to 132 is applied to the PRTs 133 to 135.

The image may not be matched little by little due to various variables such as geomagnetic field and instrument deviation during use.To correct this, the first to eighth detection units 136a may be adjusted by adjusting convergence at the factory at the time of manufacture of the product. For each of R, G, and B detected through ˜136f), a distance from each OSD pattern generated by the test pattern generator 116 is measured, and the value is stored in the memory 117 as reference data. .

That is, the test pattern generator 116 generates a pattern having a predetermined size to measure a distance from the OSD pattern for each of R, G, and B through the first to eighth sensors 136a to 136f. The generated pattern is displayed on the screen 136 according to the control signal of the microcomputer 115 through the switching unit 120 to move toward the first to eighth sensing units 136a to 136f. The output of the comparator 137 according to the amount of light detected by the first and second optical sensors A and B mounted on the first to eighth sensors 136a to 136f is a low signal. The pattern is moved until it is, and the distance value at that time is stored in the memory 117. Here, the memory 117 is composed of EEPROM.

Here, the operation principle of the comparison unit 137, as shown in Figure 7, using the first or second light sensor (A) (B) whether the light is received, the inside of the comparison unit 137 The signal input to the inverting (-) terminal of the comparator 137a is amplified twice as much as the signal input through the non-inverting (+) terminal, thereby receiving light in the middle of the second optical sensor B. When the comparator 137c receives the output signal, the comparator 137c outputs a low signal and stores the distance data up to this point in the memory 117.

That is, as shown in FIG. 4, when the auto convergence function is performed at the factory, the detected values detected by the first to eighth sensing units 136a to 136f are stored as reference values in the memory 117.

And, when the consumer executes auto convergence while using the product, the distance from the pattern is different for each of R, G, and B due to mechanical and optical geomagnetic variations.

Accordingly, as shown in FIG. 6, the distance between the measurement pattern generated by the test pattern generator 116 through the first to eighth sensing units 136a to 136f is measured by the memory ( The microcomputer 115 outputs a control signal to be corrected by the difference compared to the reference data previously stored in 117.

That is, if the distance sensed by the first to eighth detection units 136a to 136f is too close to the first and second optical sensors A and B from the start of measurement, the pattern is detected from the beginning. It becomes impossible to measure.

In addition, when the distance between the first and second optical sensors (A) (B) is too far, even if the pattern is pushed to the maximum, the pattern does not reach the first and second optical sensors (A) (B) so that the distance is measured. In order to prevent occurrence of a case where convergence correction is not possible due to this impossibility, the microcomputer 115 detects to secure a maximum margin between the first and second optical sensors A and B and a pattern. Check if the value is within 10% of the center of the preset maximum variable range.

In addition, by changing the start position and size of the pattern and storing it in the memory 117, when the new value is measured, the intermediate value between the measurement distances can be obtained by comparison with the memory 117.

As described above, the apparatus for auto-convergence correction of the projection TV according to the present invention stores the starting position and size of the pattern in the memory 117 so that the consumer can execute the auto-convergence based on the value stored in the memory 117. The distance between the first and second optical sensors A and B is measured so that the convergence can be corrected by a comparison difference with the previous value.

The automatic convergence correction method of the projection TV according to the present invention is largely divided into a method of changing the size of the pattern and a method of changing the start position of the pattern.

Here, the method of changing the size of the pattern will be described with reference to FIG. 8. First, when the auto convergence (AC) function is started, it is determined whether the auto convergence factory measurement mode is performed (S11).

Subsequently, when the determination result (S11), the auto-convergence factory measurement mode is not in effect, auto-convergence is executed (S12).

On the other hand, if the determination result (S11), the auto-convergence factory measurement mode measures the distance between the generated test pattern and the first to eighth sensing unit (S13).

Then, it is determined whether the measured distance exists within ± 10% of the middle of the pattern variable range (S14).

Subsequently, the determination result (S14), if the measured distance is within ± 10% in the middle of the pattern variable range is stored in the memory (S15).

On the other hand, if the determined result (S14), if the measured distance does not exist within ± 10% in the middle of the pattern variable range, it is determined whether the measured distance is more than the predetermined range (S16).

Here, the preset range corresponds to about 60% of the maximum variable range divided by half.

As a result of the determination (S16), if the measured distance is greater than or equal to the preset range, the size of the first step is increased (S17).

On the other hand, if the determined result (S16), the measured distance is less than the predetermined range reduces the size of the first step pattern (S18).

In addition, a method of varying the starting position of the pattern will be described with reference to FIG. 9. First, when the auto convergence function is executed, it is determined whether the auto convergence (AC) factory measurement mode is performed (S21).

Subsequently, when the determination result (S21), the auto-convergence (AC) factory measurement mode is not executed, the auto-convergence function is executed (S22).

On the other hand, if the determination result (S21), the auto-convergence (AC) factory measurement mode is executed, the distance between the pattern and the first to eighth sensing unit is measured (S23).

Then, it is determined whether the measured distance exists within ± 10% of the middle of the pattern variable range (S24).

Subsequently, the determination result (S24), if the measured distance is within ± 10% in the middle of the pattern variable range is stored in the memory (S25).

On the other hand, if it is determined in step S24 that the measured distance does not exist within ± 10% of the middle of the pattern variable range, it is determined whether the measured distance is greater than or equal to the preset range (S26).

Here, the preset range corresponds to about 60% of half of the maximum variable range.

On the other hand, if the measured result (S26), the measured distance is more than the predetermined range is reduced by the first step pattern starting position (S27).

In addition, if the determined result (S26), the measured distance is less than the predetermined range increases the start position of the first step pattern (S28).

As described above, the automatic convergence correction device of the projection TV according to the present invention measures the distance between the pattern and the detection unit when the auto convergence is executed, and adjusts the size of the pattern to have a maximum margin or starts the pattern. It is to be able to adjust.

As described above, the apparatus and method for auto convergence correction of the projection TV according to the present invention have the following effects.

First, by comparing the distance between the reference data stored at the time of factory adjustment and the pattern and sensor that are differently detected due to the deviation of the instrument, optical component, and circuit deviation, etc. Convergence can be performed.

Second, as more accurate auto convergence is performed, a higher quality screen can be provided.

Third, the user's satisfaction can be improved by providing the best screen of higher quality.

Claims (8)

A screen for displaying R, G, and B video signals, and first to eighth sensors including first and second optical sensors mounted on a predetermined area of the screen to detect patterns displayed on the screen; In one projection TV, A test pattern generator configured to generate an OSD test pattern having a predetermined size to measure a distance between the R, G, and B patterns displayed on the screen and the first to eighth sensing units; For each of the R, G, and B, the test pattern generation unit generates the R, G, and B patterns and the distance values between the first to eighth detection units and the test pattern generation unit. A memory for storing detection results of first and second photosensors mounted on the first to eighth sensing units according to a movement of the generated pattern; And, When auto convergence is executed, the test pattern generator detects a distance between the pattern generated by the test pattern generator and the first to eighth detectors, and corrects the difference by the distance stored in the memory. Projection TV auto-convergence correction device, characterized in that configured to include a control to be variable. The method of claim 1, And said memory is an EEPROM. A screen for displaying R, G, and B video signals, a pattern for each of R, G, and B displayed on the screen, and the first to eighth sensing units for R, G, and B displayed on the screen; A test pattern generation unit generating an OSD test pattern having a predetermined size to measure a distance of the first and second and second optical sensors mounted on a predetermined area of the screen to detect a pattern displayed on the screen; In the auto-convergence adjustment method of the projection TV having a first to eighth detection unit and a memory, Determining a distance between the pattern generated by the test pattern generator and the first to eighth detectors when the user selects an auto-convergence factory measurement mode; And adjusting the size of the pattern generated by the test pattern generator or the start position of the pattern to be displayed on the screen according to the determined distance. The method of claim 3, wherein Identifying the pattern and the distance Determining a distance until a high signal is input to the microcomputer while the pattern generated by the test pattern generator moves toward the first and second optical sensors mounted on the first to eighth sensors; Auto convergence correction method of the projection TV characterized in that.  The method of claim 3, wherein Adjusting the size of the pattern Determining whether a distance between the measured pattern and the sensing unit is within a preset first setting range; Storing the measured distance in the memory when the distance between the measured pattern and the sensing unit is within a preset first setting range as a result of the determination; Judging the lobe if the measured distance exceeds the second set range if the distance between the measured pattern and the sensing unit is not within the preset first set range as a result of the determination; Increasing the size of the pattern if the measured distance exceeds a second set range; And reducing the size of the pattern if the measured distance does not exceed the second set range. The method of claim 3, wherein Adjusting the start position of the pattern Determining whether a distance between the measured pattern and the sensing unit is within a preset first setting range; Storing the measured distance in a memory if the measured distance is within a preset first setting range as a result of the determination; Determining whether the measured distance exceeds the preset second setting range if the measured distance does not exist within the preset first setting range; Reducing the starting position of the pattern when the measured distance exceeds a preset second setting range; And if the measured distance does not exceed the second preset range, increasing the starting position of the pattern. The method according to claim 5 or 6, And the first setting range is a range in which the measured distance is set to within ± 10% of the middle of the pattern variable range. The method according to claim 5 or 6, And the second setting range is about 60% of a value obtained by dividing the maximum variable range of the measured distance in half.

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