KR100216031B1 - A keystone correction circuit using lookup-table - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for correcting a keystone type image distortion that can occur in accordance with the relative position of a device in relation to a projection image display device.

The present invention has been made to solve the disadvantage that the conventional keystone correction circuit has to repeatedly perform the control of the image correction function for each image line, and has a look-up table in which image correction data is stored in advance, thereby avoiding repeating the same operation. While significantly reducing the control cycle, it is also physically simplified to allow multiple functions to be controlled by one microcomputer. In addition, by making the control signal efficient, the keystone distortion correction can be performed more accurately and effectively.

Description

Keystone Correction Circuit Using Lookup-Table

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image distortion correction circuit associated with a projection type image display device, and more particularly, to a circuit for correcting a keystone type image distortion by using a lookup-table stored in advance in a memory device. will be.

In general, an image display apparatus is classified into a direct view type image display apparatus and a projection type image display apparatus according to a display method.

The direct view type image display device includes a CRT (Cathode Ray Tube). The CRT image display device has a good image quality but is limited in driving a large screen due to problems such as weight and thickness increase and price increase as the screen is enlarged. There is.

Projection type image display apparatuses include a liquid crystal display (LCD), a digital micromirror device (DMD), an AMA device (AMA), and the like. Liquid crystal display devices (LCDs) can be made large in size and thin, so that the weight can be reduced. However, such LCDs have a large loss of light due to polarization and thin film transistors for driving the LCD are formed in each pixel unit. ), There is a limit to increase the light efficiency is very low.

In order to solve the above problems, the AMA device has been developed that not only has excellent light efficiency but also has a simple manufacturing process.

An AMA image display device adjusts an optical path through such a mirror surface (hereinafter referred to as an actuator) by using a principle that a deformation portion made of piezoelectric or electrostrictive ceramic material generates and deforms an electric field by a voltage applied thereto. The light path adjusting means for projecting on the screen is the main technical content.

A projection image display device using AMA separates jack color light emitted from a light source into red (R), green (G), and blue (B) light, and then drives this light by driving an optical path adjusting device composed of actuators. Change the light path. That is, as the actuators are individually driven, the optical signals for image display are reflected on mirror surfaces inclined at predetermined angles, respectively, so that the light path is changed, and the amount of light is cut and projected onto the screen. As a result, an AMA image is displayed on the screen of the projection image display apparatus.

In the AMA image display device, the optical path adjusting means, which is the main technology, changes to a screen on which an image is displayed, and the relative position where the optical path adjusting means is installed is important. In this regard, referring to FIGS. 1 and 2, As follows.

1 is a view showing the installation state of the AMA optical path adjusting means associated with the screen for image display, and FIG. 2 is a view illustrating the distortion pattern of the projection image on the screen according to the different installation state of the AMA optical path adjusting means shown in FIG. It is for the drawing.

Regarding FIG. 1, when the apparatus 100 is installed at the center of the center so that the lens optical axis of the AMA image display apparatus 100 is perpendicular to the screen, a correct image is displayed on the screen SC. In most cases, the AMA image display apparatus 100 is used to be movable rather than fixed.

As a result, the image reproduced on the screen SC is distorted in a trapezoidal shape with a longer upper side (2a) or a longer extended side (2b) as shown in FIG. It is inevitable to obtain an abnormal image (also called keystone distortion).

FIG. 2A shows a distortion pattern of the image projected on the screen when the AMA image display apparatus 100 is installed at a relatively low position with respect to the screen, and FIG. 2B shows the AMA image display apparatus 100 relative to the screen. In this case, the distortion of the image picked up on the screen is shown.

In this case, the rectangular shape indicated by the solid line in the drawing is presented as a reference for the normal image reproduced on the screen when the AMA image display device is installed at the center position.

In the conventional AMA projection image display technology, inverse correction of a display image is performed by performing sequential image compression on a distorted image that may occur according to the installation position of the AMA image display apparatus 100 discussed above. The method has been presented.

Hereinafter, an image correction method of such a projection image display apparatus will be described with reference to FIG. 3.

3 is a schematic block diagram of a general keystone image distortion correction circuit.

In Fig. 3, reference numeral 1 denotes a microcomputer that is in charge of controlling all functions of the AMA image display device and controlling the keystone distortion correction function.

The microcomputer 1 includes a plurality of input / output ports, a KEY port for receiving a user's key input to control an image display device, a Remocon port for receiving a user's remote control command, and an image. Input ports including H-SYNC (horizontal synchronization signal) and V-SYNC (vertical synchronization signal) ports to provide horizontal and vertical synchronization to the bisplay, and the number of pixels to be compressed in each scan line when correcting a distorted image. A digital control port (d0-d7) which provides control data for the overall image display function including data relating to the eight bit signals, and the digital control port (d0-d7) by enabling the latch 1 (2) described later. Enable port (w-ld) for outputting control data, and latch 2 (3) and latch 3 (4), which will be described later, respectively, so that the start position and end position of each display line of the image can be determined. Enable ports (r-ld1, r-ld 2) and a port for generating a reset signal for initializing the counter included in the internal circuit are shown in the figure.

In the drawing, reference numerals 2, 3, and 4 denote latches 1, 2, and 3 which store and provide the control signals output from the microcomputer 1 temporarily.

5 is a counter for receiving a clock signal Clk and an H-DSP signal and outputting a counter clock signal corresponding to an image display section of a unit scanning line, and 6 is an image display control data d0-d7 of the microcomputer 1. ) Is a preset counter that receives through the latch 1 (2) and is enabled by a clock pulse to output image compression data in a first-in, first-out form.

Further, reference numeral 7 denotes the image display control data d0-d7 and the counter 5 provided when the latch 2 3 is activated by the latch enable signal r-ld1 which determines the starting point at which the image is displayed. (1) is a first comparator for comparing the counter clock signal outputted from < RTI ID = 0.0 >) < / RTI > with the same data and outputting the corresponding data. And a second comparator which compares the image display data d0-d7 provided when activated by the output data of the counter 5 and outputs the corresponding data in the same case.

Reference numeral 9 is a first in / first out (F / F) buffer for first-in, first-out to delay the counter clock signal output from the counter 5 for a predetermined time, and is applied to a reset signal provided from the microcomputer 1. Is initialized by

10 is a first-in, first-out F / F buffer for receiving a signal from the first and second comparators to control the reading of the line memory.

In the above-described projection image correction system composed of the main components described above, the user can visually detect the keystone image distortion while watching the screen, and operate the key of the main body panel or the remote control key to the microcomputer 1 to correct it. When the control command is issued, the microcomputer 1 provides the line compression data to the latch 1, the latch 2, and the latch 3 (2, 3, 4) to correct the keystone image distortion to perform the image compression operation for the purpose of distortion correction. Done.

To illustrate a typical case where an image has an aspect ratio of 640 pixels by 480 lines, and the image is compressed in 32 steps, 15 lines of image display data are grouped into one step to produce the same image compression data. Apply.

Therefore, the conventional AMA image correction system performs a predetermined compression operation on the first line of the display image, and then repeats the same compression operation for each line from the second to the 15th line to perform new image compression data. In step 2, the image data after the 16th line can be corrected.

In order to repeat the compression operation, the microcomputer 1 must continuously give control commands, which makes it difficult to control other functions, as well as KEY, Renocon, H-SYNC, Since the number of ports assigned to the keystone image correction functions such as V-SYNC (Vertical Sync Signal), d0-d7, w-ld, r-ld1, r-ld2, and reset are many, it is difficult to use the ports for other function control. It is accompanied by phosphorus difficulty.

Therefore, the present invention avoids the repetition of the same image compression operation and reduces the control cycle of the microcomputer assigned to such execution, thereby reducing the A / V (Audio.video) circuit portion and the keystone distortion correction unit in the image correction system according to the prior art. It aims to overcome the disadvantage of having to execute each control by controlling microcomputer and to control multi-function with one microcomputer.

In addition, an object of the present invention is to more accurately and effectively correct keystone distortion caused by the positional change of the AMA image display apparatus.

1 is a diagram illustrating an installation state of an AMA image display apparatus.

2 (a) is a diagram illustrating a display image projected from position a in FIG. 1,

2 (b) is a diagram illustrating a display image projected at position b in FIG.

3 is a schematic block diagram of a conventional AMA keystone image distortion correction circuit.

4 is a schematic block diagram of an AMA keystone image distortion correction circuit of the present invention.

5a and 5b illustrate signal states of the microcomputer and the preset counter in correcting the keystone image distortion according to the present invention.

FIG. 5A is a diagram illustrating the upper correction, and FIG. 5B is a lower correction.

6 illustrates signal states of the first and second comparators in the keystone image distortion correction according to the present invention.

* Explanation of symbols for main parts of the drawings

100: AMA image display device 1, 40: microcomputer

2, 12: latch 1 3, 13: latch 2

4, 14: latch 3 5, 15: counter

6, 16: frit counter 7, 17: first comparator

8, 18: 2nd comparator 9, 10, 19, 48, 50: F / F buffer

41: field counter 42: program unit

43: remote transmission and reception unit 44: up / down counter

45, 46, 47: lookup table SC: screen

In order to achieve the above object, the present invention utilizes a memory storage device to correct keystone image distortion, for example, a look-up table which stores, in advance, image compressed data for each of the 32 steps. table), and once the video signal compression of the first line is performed by receiving the user's image correction control command, the look-up table may be used for the compression of the remaining multiple lines (for example, 14 out of 15) included in the same step. It is configured to repeatedly use the compressed data stored in the several times.

In addition, the present invention constitutes a field counter in which the counting operation is started by inputting an H-SYNC signal (horizontal synchronizer) signal and the counting operation is terminated by inputting a V-SYNC signal (vertical synchronizer) in the microcomputer of the keystone distortion correction circuit of the present application. By using the V-SYNC signal and the H-SYNC signal to compensate for the control of the keystone distortion, the conventional image correction operation is performed based on only the H-SYNC signal. It is characterized by being configured.

4 is a block diagram showing a schematic configuration of the keystone distortion correction circuit of the present invention characterized by the above-described description with respect to the projection-type image display apparatus.

Hereinafter, with reference to Figure 4 will be described in more detail the configuration and effect of the present application.

In Fig. 4, reference numeral 40 denotes a microcomputer which is in charge of a number of other image display controls including a keystone type image distortion correction function and an audio / video function which may occur due to the positional change of the image display apparatus.

Reference numeral 41 is a field in which the counting operation is started by the horizontal synchronizing signal (H-SYNC) and the value accumulated by the vertical synchronizing signal (V-SYNC) is cleared, and Key H-SYNC (key horizontal synchronizing signal) is generated. A counter, 43 is a remote transmission and reception unit for receiving a remote control command signal of a system user and providing this control signal to a corresponding function processing unit, and 42 is a keystone correction function control signal through a user panel key operation or a remote control key operation. Keystone for inputting directly or through the remote transmitter / receiver 43 to activate the field counter 41 and generate control signals such as keystone on / off and top / bottom correction. As the distortion correction program unit, 41, 42, and 43 blocks constitute the microcomputer 40.

In FIG. 4, reference numeral 44 denotes Key H-SYNC which is enabled by the top / bottom correction signal provided from the program unit 42 and input from the field counter 41. The up / down counter is configured to count the number of pulses of the key horizontal sync) signal upward or downward and to be reset by the vertical sync signal V-SYNC.

45, 46, and 47 are lookup-tables as predetermined memory elements or memories, for example, 32 stages of image compression data are sequentially stored in advance and used for correction of keystone image distortion.

Similar functional blocks to those of the conventional keystone image distortion correction circuit shown in FIG. 3 are indicated by adding an Arabic numeral '1' before the reference numeral of FIG.

Reference numerals 12, 13, and 14 denote latch 1, latch 2, and latch 3 elements for temporarily storing each input data input through the input terminals and providing the output terminals, and 48 and 19 transmit data in a first-in first-out mode. 15 are counters that count the clock signal through the F / F buffer 48 and perform a new counting operation by initializing the count value to '0' by the reset signal. .

In FIG. 16, reference numeral 16 denotes a clk signal by loading image information data latched on the latch 1 (12) based on the H-SYNC (horizontal synchronization) signal based on the H-SYNC (horizontal synchronization) signal. The preset counter is configured to generate an output signal when the count value reaches the predetermined set value at this time.

17 and 18 respectively compare the count value of the counter 15 with the image correction data provided through the latch 2 (13) and the latch 3 (14), respectively. It is a first comparator and a second comparator.

Reference numeral 50 is an F / F buffer for controlling the reading of the line memory by receiving the signal of the first comparator 17 or the second comparator 18.

In the keystone image distortion correction circuit of the present invention configured as described above, the user finds a distortion of the image visually displayed and gives an image correction command to the program unit 42 through the remote transmitter / receiver 43 by operating a remote control key. The image correction command is directly issued through the main panel key input.

The program unit 42 reads such an image correction command to determine a correction direction according to a keystone on / off signal, which is a signal for enabling keystone correction, and a distortion shape of the image. In addition to generating a bottom (up / down correction) signal, the filter counter 41 is activated to provide a field-level horizontal synchronization signal (Key H-SYNC).

At this time, when the AMA image display device is located at a relatively high position with respect to the screen, as described above with reference to FIGS. 1 and 2, the Top / bottom signal is changed to 'ToP state', The up / down counter 44, which is enabled on the basis of the bottom signal, functions as an up counter. Otherwise, if the position is relatively low, the top / bottom signal is 'bottom state'. Since the up / down counter 44 functions as a down counter.

On the other hand, the lookup tables 45, 46, and 47 receive the output of the up / down counter, read out the multi-stage image distortion correction data stored in the lookup table in advance, and look up the tables 45, 46, 47, It is stored in the connected latch 1 (12), latch 2 (13), and latch 3 (14) parts. The latch 1 (12), latch 2 (13), and latch 3 (14) parts of which image distortion correction data is temporarily stored as described above are latched and transferred to the next stage based on the H-SYNC signal. .

The line correction data stored in the latch 1 (12) is latched by the preset counter 16. The preset counter 16 counts the clk signal to perform image data correction on one line of the keystone-distorted image. When the count value reaches the latched data value, an output signal for controlling the write enable terminal of the line memory for recording the image display data is generated.

The line start point data stored in the latch 2 (13) is latched by the first comparator 17. The first comparator is input by the keystone on / off signal of the program unit 42 of the microcomputer 40. Compare the enabled and latched data with the output data of the counter 15 to generate an output pulse for controlling the line memory reading corresponding to the start position of the F / F buffer 50 image display line when the two data are the same. .

Similarly, the line endpoint data stored in latch 3 (14) is latched by second comparator 18, and the second comparator is likewise enabled by a keystone on / off signal so that the latch data and the counter ( 15) When the output data are the same, the output pulses for controlling the line memory reading corresponding to the end position of the image display line are generated by the F / F buffer 50.

The counter 15 counts the clk signal input through the F / F buffer 48 and provides this counting data to the first and second comparators as well as outputs to the F / F buffer 19 to H-. A DLY (DELAY) H-DSP signal, which is a signal obtained by delaying a DSP signal for a predetermined time, is generated.

This time delay takes into account the driving time required to drive the optical path control apparatus using the image display data of the line memory.

Images distorted according to the operation of each component as described above are divided into a plurality of stages, and the same image data correction operation can be repeatedly performed with only one micom control command for a plurality of lines included in each compression stage, and accurate display. Such image data correction can be made at the start point and the display end point.

5A and 5B are timing diagrams showing the state of the respective control signals provided from the microcomputer 40 and the output signal state of the preset counter 15 to execute the keystone image distortion correction function according to the present invention.

FIG. 5A illustrates a case where the position of the AMA image display apparatus of the present invention is relatively upper side, and FIG. 5B illustrates a case where the position of the AMA image display apparatus is relatively lower side.

6 is a timing diagram showing the output signal states of the preset counter 16 and the first and second comparators 17 and 18 when performing keystone image distortion correction.

Hereinafter, the keystone correction function of the present invention will be described with reference to specific examples with reference to the fourth, fifth and six appended hereto.

As an example, assume that the position of the AMA image display device is a position higher than the center of gravity (Top state) relative to the screen. In addition, the image reproduced on the screen is set to a general 640 pixels x 480 lines. At this time, the visible image distortion observed by the user becomes a trapezoidal shape (Top keystone) whose lower side is longer than the upper side, and it is easy to see that the later lines require more pixel data compression in sequential line correction.

Correction of the image lines is performed in 32 steps, and 15 lines (480/32) constitute one step in one group so that the same number of image data compression is performed for each line.

In the fifth embodiment, the program unit 42 in the microcomputer 40 sets the Top / bottom (up / down correction) signal to 'Top state' and the Keystone on / off signal to '1'. Field counter 41 is enabled at the same time.

The field counter 41 is reset based on the V-SYNC signal and counts pulses of the H-SYNC signal.

The up / down counter 44 operates as an up counter according to the Top / bottom (up / down correction) signal of the program unit 42, and counts up the Key H-SYNC signal pulse to increase the count value. Addresses of lookup tables 45, 46, and 47 corresponding to.

Each of the up-up tables 45, 46, and 47 temporarily stores each keystone image distortion correction data stored at a specified address in latch 1 (12), latch 2 (13), and latch 3 (14) connected to each table. Remember

The three latch elements 12, 13, 14 are latch-enabled by the same H-SYNC (horizontal synchronizer) signal provided to the field counter 41, and latch the data with the preset counter 16.

The preset counter 16 outputs data stored at the address of the lookup table 45 for every H-SYNC pulse, and at this time, the signal output state of the field counter 41 becomes '0' and the image correction is performed. This completes one step and produces the same output until the data at the new address is latched.

In addition, latch 2 13 latches data with the first comparator 17, and the first comparator 17 compares the latched data with the data provided from the counter 15, and if the two data are the same, '0'. Falls to the level.

The F / F buffer 50 receiving such a signal outputs a signal (read pulse) for controlling the reading of the line memory to determine the start position of the image display line.

Similarly, latch 3 (14) latches data with second comparator 18, compares it in second comparator 18, and then falls to the '0' level in the same case. In response, F / F buffer 50 Outputs the line memory read control signal to determine the end position of the image display line.

The counter 15 counts the clock signal input through the F / F buffer 48 and outputs a DLY H_DSP signal by delaying it 40 clocks in the next stage F / F buffer 19.

Meanwhile, another embodiment shown in FIG. 5B corrects keystone distortion generated when the position of the AMA actuator is lower, and the top / bottom signal becomes 'bottom state' so that the up / down counter 44 ) Is similar to the first embodiment described above except that data read and transfer are executed in order starting from the final address of the lookup tables by operating as a down counter, and thus the description thereof will be omitted.

According to the embodiment of the present invention, the specific configuration and effect of the present invention are described above. In the present invention, a look-up table is compared with a conventional projection image correction technique that repeats the same correction control for a plurality of image lines. The sequential image correction data is stored in stages and the keystone distortion correction is effectively solved by utilizing not only H-SYNC (horizontal synchronization signal) but also V-SYNC (vertical synchronization) signal as a reference signal. It was.

As a result, according to the present invention, the number of ports of the microcomputer used for image correction of the projection type image display apparatus can be greatly reduced, and only a part of the control cycle can be allocated to image correction, so that other functions can be controlled.

In addition, the present invention does not control based on the width of the H-SYNC (horizontal synchronization) signal as in the conventional method, so that accurate control is made and keystone distortion correction is effectively performed.

Claims (2)

A circuit for correcting keystone image distortion associated with a projection image display apparatus, comprising: a field counter (41) in which a counting operation is started based on a horizontal synchronous signal and initialized based on a vertical synchronous signal, and predetermined control for keystone image distortion correction The microcomputer 40 which is responsible for keystone image distortion correction and other image display function control including a program unit 42 and a remote transmitter / receiver unit 43, and an up counter or a down counter according to a control signal of the program unit 42. A look-up table 45, 46, 47, which sequentially stores pre-stored up / down counters 44 for operating a multi-level image correction data, each step comprising a plurality of image lines; The latch 1, latch 2, and latch 3 elements 12, 13, and 14 for temporarily storing and latching data provided from the lookup tables 45, 46, 47, and the clock signal are counted and reset by the reset signal input. The counter 15 to be converted, the preset counter 16 for loading the data of the latch 1 12 and generating an output signal when the count value reaches this, the data of the latch 2 13 and the counter ( A first comparator 17 for comparing the count values of 15) and outputting the same if they are the same; a second comparator 18 for comparing the count values of the data of the latch 3 14 and the counters 15 and outputting the same; F / F buffers 48 and 19 for providing input data in a first-in-first-out form and F for controlling line memory readings in response to signal inputs of the first comparator 17 or the second comparator 18. / F buffer 50, characterized in that the keystone image correction circuit. 2. The lookup tables (45, 46, 47) of claim 1, wherein 15 lines (480/32) are configured in one group so that the same number of image data compression is performed for each line in a group. Line correction data of four steps is stored, the lookup table 45 stores line correction data, the lookup table 46 stores line start position data, and the lookup table 47 stores line end position data. Keystone image correction circuit, characterized in that is stored.