KR100490160B1 - Control method of color wheel - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital light processor (DLP) system. In particular, a method for synchronizing an R.G.B segment with an image signal by controlling the speed and color phase of a color wheel in a DLP system. It is about.

The present invention detects the speed and color phase of the color wheel, compares the speed and color phase of the synchronization signal to measure the phase difference, and based on the phase difference in the method for controlling the speed and color phase of the color wheel, a predetermined angle Applying monochromatic light by varying the index delay value, detecting the displayed amount of light according to the changed index delay value, extracting an average amount of light, and changing and storing the index delay value and the extracted light amount as digital data. And extracting a maximum value of the stored amount of light and setting an index delay value corresponding to the maximum value.

Description

Color wheel speed and color phase control method {CONTROL METHOD OF COLOR WHEEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital light processor (DLP) system. In particular, a method for synchronizing an R.G.B segment with an image signal by controlling the speed and color phase of a color wheel in a DLP system. It is about.

DLP (DLP) is a new display method that contrasts with a liquid crystal display (LCD) projection system, and realizes high definition image quality by using a light reflecting element.

In other words, a device in which hundreds of thousands of reflective elements are integrated on one chip to selectively reflect light to express high brightness and high resolution images.

It is an extension of the projection type screen display technology that has been developed through projectors, CRTs, and liquid crystal displays (LCDs), but it has a characteristic of being reflective compared to LCDs already commercially available.

DLP is a signal processing chip for controlling mirrors of DMDs based on a digital micro-mirror device (DMD) in which millions of micro mirrors matching the display resolution are integrated. chips).

1 is a conceptual diagram of a mirror configuration of a conventional DMD chip.

Referring to FIG. 1, a DMD chip is manufactured using a semiconductor process, and hundreds of thousands to millions of mirrors having a size of 16 × 16 μm are formed in an area of a thumb-sized chip.

In the case of a high definition signal, an analog-to-digital (A / D) converted video signal is typically composed of 1280 pixels in the horizontal direction and 720 lines in the vertical direction.

The converted video signal corresponds to the micromirror of each pixel one-to-one to control the on / off state of the corresponding mirror, and to show the on state of the mirror which merely performs the on / off operation to express the brightness of the pixel. Control the time to keep.

The chip's mirror electronically rotates about 100 times per second, expressing white when rotating at the angle reflecting light (On) and black when rotating at the angle not reflecting light (Off). do.

In the case of displaying a black and white image, the refresh cycle of the 60 Hz image is about 1 m / sec and about 16 mSec.

According to the image signals of the mirrors within this time, the ON state time is the longest to express the brightest light of 16 mSec, and the shortest time to express dark light of 0 mSec.

When 8mSec is on, it expresses light of medium brightness.

In the case of CRT display, the method of expressing light and dark actually controls the amount of emission of the pixel by strongly or weakening the electron beam hitting the phosphor, but in the case of DLP, the time of On state To adjust the brightness difference.

If the speed of refreshing is fast enough, the difference in brightness can be realized by adjusting the time of on-state due to human visual characteristics.

Bit splitting is a technique of varying the time to keep the ON state according to the pixels in order to realize the pixel brightness difference.

In the case of the bit division technique, in case of 60Hz image, it is left on for 8mSec to express medium brightness, and is turned off for the remaining 8mSec, and the on time is driven for the front 8mSec and turned off for the remaining 8mSec. Rather than turning it off, the time unit is limited to 1mSec, so 1mSec is on, 1mSec is off, 1mSec is on, and 1mSec is off .... It is a technique to make this 8mSec.

By using this bit splitting technique, it is possible to prevent the brightness of pixels at the image boundary of the moving picture from being noticeably brightened.

When expressing color, three DMD chips are used or three light sources are alternately illuminated at high speed to express colors using an afterimage effect of eyes.

When describing a color image using one DMD chip, pure white RGB light is generated by passing white light from a white lamp through a color wheel coated with an RGB filter. .

For example, when the RGB filter is divided into three parts, when the color wheel is rotated at 60 Hz corresponding to the refresh rate of the image, the time for the primary light to shine is about 5.5 mSec.

After decomposing the video signal into RGB, A / D conversion, each pixel is decomposed into RGB values, and then converted into data capable of driving the DMDM, and matching the moment when the primary color light passing through the color wheel illuminates the DMDM. Color images are implemented by turning on / off the DMDM according to the pixel value of the corresponding color.

RGB colors are displayed at the same time, not at the same time. However, by speeding up the color wheel to reduce the time difference, the colors are added using the afterimage effect.

2 is a diagram for explaining a DLP optical system.

Referring to Figure 2, the optical system is to provide light to be illuminated on the DMD (14), each micro-mirror is turned on (On) or off depending on the image signal to the screen side or off (Off) Determines whether the light will shine toward the no screen.

In the conventional DLP optical system, a lamp 10 through which light is generated, a rod lens 11 through which light generated from the lamp 10 passes, and white light passing through the rod lens 11 are color-divided into RGB. A color wheel 12, a condensing lens 13 in which light passing through the color wheel 12 is collected, a prism 15 in which light passing through the condensing lens 13 is reflected, And a projection lens (16) for enlarging the light reflected by the prism (15) to the screen and the reflection of the reflected light from the DM14 (14).

Referring to the operation of the conventional DLP optical system based on the above configuration, the white light emitted from the lamp 10 is focused by the internal curvature of the reflector, the focused light is a light tunnel (light tunnel) or a bar lens ( Rod Lens) is passed through.

The bar lens 11 is formed by bonding four small elongated mirrors to face each other, and the light passing through the bar lens 11 is diffusely reflected so that the brightness distribution is uniform.

The uniformity of the brightness of the light is the same as the uniformity of the light finally shining on the screen, and the rod lens 11 having this function becomes an important optical component in the projection display.

Light passing through the rod lens 11 passes through the color wheel 12 for color division, and the color wheel 12 is rotated in accordance with the vertical synchronization of the image.

Light passing through the color wheel 12 passes through the condensing lens 13 and is reflected by the prism 15 to the DMD 14.

The prism 15 may be totally reflected or transmitted according to the incident angle of light.

Light shining on the DMMD 14 is directed toward or off the screen depending on the on / off state of the micromirror controlled in accordance with the sampled pixel value.

The light reflected by the DMDM 14 and directed toward the screen is enlarged to pass through the projection lens 16 to be reflected on the large screen.

3 is a diagram illustrating a color wheel of the DLP optical system.

Referring to FIG. 3, the color wheel 12 is driven by a DC motor 17, and an RGB filter is attached thereto.

In addition, an index mark 18 is attached to match the rotational speed and color phase of the color wheel 12 with the synchronization signal of the video signal.

The Algibi filter can be attached to each of the 360 divided into three parts, by dividing into six equal parts so that the same color is attached twice so as to reduce the degree of rotation of the DC motor 17 to transmit any color. The rotation speed of 17 can be reduced.

The size corresponding to the width of the light passing through the rod lens 11 is called a spot size, and since the primary color light is not formed while the light is straddling the edge of the Algibi filter, such light represents an image. It is common not to use it.

However, when all the light of all boundary surfaces are collected, white light is formed.

The index mark 18 is used as a recognition mark for matching the rotational speed and color phase of the color wheel 12 with the synchronization signal of the video signal.

In addition, the index mark 18 uses black tape or paint which absorbs light, and the reflection coefficient is attached to a predetermined portion of the DC motor 17.

By illuminating the infrared rays toward the index mark 18 and detecting the reflected infrared rays, the speed and color phase of the color wheel 12 rotated by the DC motor 17 are matched with the synchronization signal.

However, the position where the index mark 18 is attached varies slightly from step to step, and when it is out of a fixed position, the image signal and the light by the color wheel 12 do not coincide, and thus high quality images cannot be obtained.

In order to solve this problem, a register called a color wheel index delay is placed in the drive of the DMDM, and the error of the mounting position of the index mark 18 is displayed in the ROM for each product while viewing the screen during production. Remember to call out the error value every time the product is operating and adjust the error.

The error value can be adjusted from 0 to 360 degrees.

The method of finding the error of the attachment position of the index mark 18 is to apply a test pattern and check whether the expected color appears on the screen or whether the screen flutters by changing the error value little by little. do.

4 is a flowchart illustrating adjusting an error value in a conventional color wheel.

Referring to FIG. 4, when white light emitted from the lamp passes through the color wheel 12, it is converted into the primary color light by the Algivy filter of the color wheel 12.

The primary color light is reflected by the prism 15 and input to the DMDM 14 and passes out of the screen through the prism 15 in accordance with the on / off of the DM14, or is enlarged through the projection lens 16. To be reflected on the screen.

On / off of the DM14 is performed by converting the image synchronization signal and the image data input to the data formatter 25 into a bit string suitable for driving the micro mirror of the DM14.

The sensor 20 detects the reflected light by reflecting infrared rays on the index mark 18 attached to the DC motor, so that the rotation speed and color phase of the color wheel 12 can be known, and the output of the sensor 20 is an index delay setting device. (Index Delay Setting) 21 is input.

While observing the screen, an error value is input to the index delay setter 21 using the microcontroller 26, and the input error value delays the output signal of the sensor 20 at a predetermined interval.

The output of the adjusted index delay setter 21 is input to the phase difference detector 22, and the phase difference detector 22 compares the output of the index delay setter 21 and the phase of the image synchronization signal to obtain a phase difference between the PWM generators. 23).

The signal of the PWM generator 23 controls the motor driver 24 to drive the motor to which the color wheel 12 is coupled.

That is, the error value detected by the sensor 20 with respect to the attachment position of the index mark 18 is adjusted by manually delaying the error value while viewing the screen using the microcontroller 26.

Subsequently, the index delay setter 21 is readjusted by applying a test pattern while checking the screen of the screen and checking whether the expected color appears on the screen or whether the screen flutters.

As described above, the index delay method of the conventional color wheel has an disadvantage in that an error occurs because it is adjusted experimentally while observing a screen displayed on the screen.

In addition, there is a disadvantage in that manpower and time are wasted by manually adjusting the index delay.

The present invention has been made to solve the above problems, and an object thereof is to block the occurrence of an error by automatically correcting an error value between an image synchronization signal and an index mark of a color wheel.

In addition, an object of the present invention is to improve the productivity by reducing the time and manpower to adjust the error value of the index mark.

Speed and color phase control method of the color wheel according to the present invention for achieving the above object detects the speed and color phase of the color wheel, and compares the speed and color phase of the synchronization signal to measure the error value, the error value A method of controlling the speed and color phase of a color wheel, the method comprising: applying a monochromatic light by varying an index delay value at a predetermined angle, and detecting an amount of light displayed according to the changed index delay value to determine an average amount of light. Extracting, changing and storing the index delay value and the extracted light amount into an electrical signal, extracting a maximum value of the stored light amount, and setting an index delay value corresponding to the maximum value; It is characterized by.

Hereinafter, a speed and color phase control method of a color wheel according to the present invention will be described with reference to the accompanying drawings.

5 is a view for explaining a speed and color phase control method of a color wheel according to the present invention.

Referring to FIG. 5, a method of detecting a speed and a color phase of a color wheel, comparing an speed and a color phase of a synchronization signal, measuring an error value, and controlling the speed and color phase of the color wheel based on the error value. The method may further include: applying monochromatic light by varying an index delay value at a predetermined angle, extracting an average amount of light by sensing a displayed amount of light according to the changed index delay value, and electrically extracting the index delay value and the extracted amount of light. Changing and storing the signal, extracting a maximum value of the stored amount of light, and setting an index delay value corresponding to the maximum value of the amount of light.

In more detail, when the white light emitted from the lamp passes through the color wheel 12, it is converted into monochromatic light by the Algivy filter of the color wheel 12.

The monochromatic light is reflected by the prism 15 and input to the DMDM 14 and passes out of the screen through the prism 15 in accordance with the on / off of the DM14, or is enlarged through the projection lens 16. It will be illuminated on the screen.

The on / off of the DM14 is performed by converting the image synchronization signal and the test signal input to the data formatter 25 into a bit string suitable for driving the micromirror of the DM14. Is converted.

The test signal is preferably a predetermined monochromatic light.

The index mark 18 attached to the DC motor allows the sensor 20 to detect infrared light and reflect the reflected light so that the rotation speed and color phase of the DC motor can be known.

The index mark 18 is attached to one side of the motor, and a tape or paint that absorbs light having a large difference in reflection coefficient from a motor made of steel is suitable.

The output of the sensor 20 is input to an index delay setting 21.

The output of the index delay setter 21 is input to the phase difference detector 22, and the phase difference detector 22 compares the phase of the image synchronization signal with the output of the index delay setter 21 to determine the phase difference between the PWM generators 23. Type in

The signal of the PWM generator 23 controls the motor driver 24 to drive the motor to which the color wheel 12 is coupled.

As described above, the monochromatic light applied while the color wheel 12 rotates is reflected by the prism 15, and only a predetermined monochromatic light is displayed on the screen according to the reflection angle of the DM14 according to the test signal.

The sensor 27 which detects a predetermined monochromatic light among the light shining on the screen is installed, and the light amount is measured.

As the light amount measured by the sensor 27 passes through the low pass filter LPF, noise and the like are removed, and the average light amount is extracted.

The low pass filtered light amount is converted into digital data via an A / D converter 29 built in the microcontroller 26 and input to the maximum value detector 30.

The maximum value detector 30 is designed to read and write from the memory and the memory, and can store the amount of light and extract the maximum value of the amount of light.

As the value of the index delay setter 21 is changed to a predetermined angle, the phase of the color wheel 12 sensed by the sensor 20 is delayed by a predetermined angle, and passes through the phase difference detector 22 and the PWM generator 23. The signal controls the motor driver 24 to change the phase of the color wheel 12.

The value of the index delay setter 21 varies from 0 degrees to 360 degrees, and increases from 0 degrees to 1 degree in increments of 360 degrees.

In order to measure the value of the index delay setter 21 more precisely, the angle varying from 0 degree to 360 degrees may be increased smaller.

When the phase of the color wheel 12 changes, the amount of light detected by the sensor 27 changes, and thus the average amount of light that has passed through the low pass filter 28 changes.

The amount of light changed according to the value of the index delay setter 21 is input to the maximum value detector 30 through the A / D converter 29, and the maximum amount detector 30 receives the amount of light according to the value of the index delay setter 21. The maximum amount of light is extracted by comparing the changes of.

When the value of the index delay setter 21 in which the maximum amount of light is measured is input to the index delay setter 21, an error value according to the attachment position of the index mark 18 is corrected.

That is, the index delay setter 21 is manually changed in the related art, and a method of inputting an appropriate index delay setter 21 value by observing a screen of the screen is automatically performed.

FIG. 6 is a diagram illustrating an output of a sensor and an output of a low pass filter according to an index delay in a method of controlling a speed and a color phase of a color wheel according to the present invention.

Referring to FIG. 6, first, when the index delay is correct, the output of the R sensor is matched with the test signal. When the index delay is not correct, as shown in the figure, the output of the R sensor according to the test signal is shown. Some of the R sensors will not be detected.

Therefore, when looking at the average value of the light amount according to the output of the low pass filter, the average value of the light amount when the index delay is correct is larger than the average value of the light amount when the index delay is not accurate.

Therefore, after extracting the average value of the quantity of light while changing the value of the index delay from 0 degree to 360 degrees, the error of the index mark is corrected by the index delay value corresponding to the quantity of light having the highest average value.

7 is a flowchart illustrating a process of extracting the most accurate index delay value while changing the index delay value in the color wheel speed and color phase control method according to the present invention.

Referring to FIG. 7, when the value of the index delay is 0 degrees (S100), the output of the sensor for detecting the amount of light is stored. (S101)

It is determined whether the index delay value is 360 degrees (S102), and if the index delay value is not 360 degrees, the amount of light corresponding to each index delay value is increased until the index delay value is 360 degrees while increasing the index delay value by 1 degree (S103). Save it.

When the index delay value is 360 degrees, the output value of the largest sensor is extracted, and the index delay value that produces the output value of the sensor is determined.

Therefore, the most accurate index delay value is measured and input to the index delay setter to realize a high quality screen.

The speed and color phase control method of the color wheel according to the present invention can automatically reduce the manpower and time due to the adjustment of the index delay because the index delay value is automatically determined.

In addition, the speed and color phase control method of the color wheel according to the present invention can extract a high-definition index delay value to configure a high-quality screen.

1 is a conceptual diagram of a mirror configuration of a conventional DMD chip.

2 is a diagram for explaining a DLP optical system.

3 illustrates a color wheel of a DLP optical system.

4 is a flowchart illustrating adjusting an error value in a conventional color wheel.

5 is a view for explaining a speed and color phase control method of a color wheel according to the present invention;

6 is a view for explaining the output of the sensor and the output of the low pass filter according to the index delay in the method of controlling the speed and color phase of the color wheel according to the present invention.

7 is a flowchart illustrating a process of extracting the most accurate index delay value while changing the index delay value in the speed and color phase control method of the color wheel according to the present invention.

<Explanation of symbols for main parts of drawing>

10; Lamp 11; Rod lens

12; Color wheel 13; Condensing lens

14; DM 15; prism

16; Projection lens 17; motor

18; Index mark 20; sensor

21; Index delay setter 22; Phase difference detector

23; PWM generator 24; Motor driver

25; Data formatter 26; Microcontroller

27; Sensor 28; Low Pass Filter

29; AD converter 30; Value sensor

Claims (2)

A method of detecting a speed and a color phase of a color wheel, measuring a phase difference by comparing a speed and a color phase of a synchronization signal, and controlling a speed and a color phase of a color wheel based on the phase difference, an index delay at a predetermined angle. Applying monochromatic light with varying values, sensing the displayed amount of light according to the changed index delay value, extracting an average amount of light, changing and storing the index delay value and the extracted amount of light as digital data; And extracting a maximum value of the stored amount of light, and setting an index delay value corresponding to the maximum value. The method of claim 1, The method of controlling the speed and color phase of a color wheel, characterized in that the step of changing the index delay value at a predetermined angle and applying monochromatic light sequentially increases from 0 degrees to 360 degrees.