KR100623081B1 - Optical pointing system and movement value control method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pointing system and a method for calculating a motion value of the system, comprising a sensor circuit, the sensor circuit sensing an light reflected from a work surface and generating an image signal, an image signal and / or a motion. A maximum search window variable circuit for inputting a value to vary the maximum search window size, and a motion value calculation circuit for calculating a motion value of an image signal using the maximum search window having a variable size. Therefore, an accurate motion value can be found by calculating a motion value by varying one or more of the maximum search window and the sampling rate according to one or more values of light quantity and motion speed.

Description

OPTICAL POINTING SYSTEM AND MOVEMENT VALUE CONTROL METHOD THEREOF}

1 is a view showing a general optical pointing system.

2 is a block diagram of a sensor circuit of a conventional optical pointing system.

Fig. 3 is a block diagram of the sensor circuit of the first embodiment of the optical pointing system of the present invention.

4 is a block diagram of the sensor circuit of the second embodiment of the optical pointing system of the present invention.

Fig. 5 is a block diagram of the sensor circuit of the third embodiment of the optical pointing system of the present invention.

Fig. 6 is a block diagram of the sensor circuit of the fourth embodiment of the optical pointing system of the present invention.

FIG. 7 is a block diagram of an embodiment of a clock control circuit of the optical pointing system shown in FIG.

8A to 8C illustrate a method of adjusting the maximum search window of the optical pointing system of the present invention.

<Description of the symbols for the main parts of the drawings>

210, 310: image sensor

220, 320: A / D converter

230, 330: shutter control circuit

240, 350, 350: Motion value calculation circuit

340: maximum search window variable circuit

370: sampling rate variable circuit

380: maximum search window and sampling rate variable circuit

390: clock control circuit

572: clock division circuit

574: Multiplexer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pointing system, and more particularly, to an optical pointing system capable of adaptively changing a maximum search window and / or a sampling rate according to an amount of incident light and a moving speed, and a method of calculating a motion value of the system. It is about.

Fig. 1 shows a general light pointing system, which is composed of a light source 8, a lens 5, and an image sensor 3 in a sensor circuit (not shown).

In Fig. 1, 2 represents a work surface, and 4, 6, and 7 represent light. In the light pointing system shown in Fig. 1, the light 7 from the light source 8 is reflected on the work surface 2, and the reflection thereof. The light 6 passes through the lens 5. The light 4 passing through the lens 5 is input to the image sensor 3 composed of a complementary metal oxide semiconductor (CMOS) device.

The image of the work table 2 is continuously sensed by the image sensor 3 and stored as image data in a memory (not shown) in the sensor circuit. The sensor circuit calculates a correlation value between the image data currently input into the memory and the image data stored in the memory first, calculates a motion value, and transmits it to a system such as a computer.

2 shows a block diagram of a sensor circuit of a conventional optical pointing system, in which an image sensor 210, an A / D converter 220, a shutter control circuit 230, a motion value calculation circuit 240, and a PC interface are shown. It consists of a circuit 250.

The function of each of the blocks illustrated in FIG. 2 will be described as follows. The image sensor 210 detects image data by receiving light reflected through the lens under the control of the shutter control signal SHCO. The A / D converter 220 receives an analog signal output from the image sensor 210 and converts the analog signal into a digital signal. The shutter control circuit 230 uses an image data, which is an output signal of the A / D converter 220, to control the electronic shutter (not shown) in the image sensor 210 so that the output of the A / D converter 220 has a constant distribution. A shutter control signal SHCO is generated for controlling. An electronic shutter (not shown), not shown, is composed of a CMOS device in the sensor circuit. The motion value calculation circuit 240 calculates and outputs a motion value of image data, which is an output signal of the A / D converter 220, at a fixed sampling rate using a fixed maximum search window and a mask window. The PC interface circuit 250 transfers the motion value output from the motion value calculation circuit 240 to the computer (not shown) at a fixed report rate. That is, the PC interface circuit 250 stores the motion value output from the motion value calculation circuit 240 and transmits the motion value at a fixed report rate required by a computer (not shown).

The sensor circuit of the conventional optical pointing system as described above always outputs a motion value by calculating a correlation value between the image frame data and the newly input image frame data, which are first input into the memory at a constant sampling rate. For example, all circuits in the sensor circuit were operated based on a fixed sampling rate of 1500 or 2000 times per second. In addition, the sensor circuit of the conventional optical pointing system obtains the motion value and delivers the result to the computer at a fixed report rate. In addition, the conventional optical pointing system could change the operation time of the electronic shutter controlling the amount of light input to the image sensor 210 only within the predetermined shutter exposure time, and also fix the motion value calculation circuit 240. The maximum search window was used to calculate correlations at a given sampling rate.

By the way, when the sampling rate, shutter exposure time, and maximum search window are determined, when the amount of light is extremely reduced, the optical pointing system operates to increase the amount of light by increasing the exposure time of the electronic shutter to satisfy the amount of input light. However, even if the required amount of light is not input even when the maximum time of the shutter exposure time interval corresponding to the predetermined sampling rate is reached, the image sensor may not properly express the floor pattern. As such, when the amount of light is insufficient, the light pointing system cannot distinguish the value of the floor pattern and thus cannot find the motion value.

An object of the present invention is to provide an optical pointing system that can find the exact motion value by varying the maximum search window according to the amount of light and / or the speed of motion.

Another object of the present invention is to provide an optical pointing system capable of finding an accurate motion value by varying the sampling rate according to the amount of light and / or the speed of motion.

Still another object of the present invention is to provide a method of calculating a motion value of an optical pointing system for achieving the above object and other objects.

A first aspect of the optical pointing system of the present invention for achieving the above object and other objects includes a sensor circuit, wherein the sensor circuit senses light reflected from the surface of the work surface by controlling the exposure level in response to the shutter control signal. An image sensor for generating an analog image signal, an analog / digital conversion circuit for converting the analog image signal into a digital image signal, and outputting the shutter; a shutter control circuit for inputting the digital image signal to generate the shutter control signal; A maximum search window variable circuit for varying a maximum search window size by inputting at least one of a signal and a motion value, and a motion value for calculating the motion value of the digital image signal using the maximum search window of the variable size Characterized in that it comprises a calculation circuit do.

A second aspect of the optical pointing system of the present invention for achieving the above object and other objects comprises a sensor circuit, the sensor circuit detects light reflected from the work surface by controlling the exposure level in response to the shutter control signal. An image sensor for generating an analog image signal, an analog / digital conversion circuit for converting the analog image signal into a digital image signal, and outputting the shutter; a shutter control circuit for inputting the digital image signal to generate the shutter control signal; A sampling rate control signal for varying the sampling rate by inputting at least one of a signal and a motion value, a sampling rate and a maximum search window variable circuit for varying the size of the maximum search window, and responding to the sampling rate control signal The variable searchlight by Using the RHS is characterized in that a motion value calculating circuit for calculating the motion value of said digital image signal.

Motion value calculation method of the optical pointing system of the present invention for achieving the above another object is to detect the light reflected from the surface of the workbench to generate an image signal, input and sampling at least one of the image signal and the motion value A sampling rate and maximum search window variable step of generating a sampling rate control signal for varying the rate and varying the size of the maximum search window; and using the variable maximum search window in response to the sampling rate control signal; And a motion value calculating step of calculating the motion value of the signal.

Hereinafter, an optical pointing system and a method of calculating a motion value of the system according to the present invention will be described with reference to the accompanying drawings. FIG. 3 is a block diagram showing a configuration of a sensor circuit of the optical pointing system of the present invention. The image sensor 310, the A / D converter 320, the shutter control circuit 330, the maximum search window variable circuit 340, the motion value calculation circuit 350, and the PC interface circuit 360 are included. In Fig. 3, the maximum search window variable circuit 340 is composed of a light amount detector 342, a motion speed detector 344, and a maximum search window calculation circuit 346.

The function of each of the blocks shown in FIG. 3 will be described below.

The image sensor 310 receives the light reflected from the surface of the work table (not shown) under the control of the shutter control signal SHCO. The A / D converter 320 receives an analog signal from the image sensor 310 and converts it into a digital signal. The shutter control circuit 330 controls the electronic shutter (not shown) in the image sensor 310 so that the output of the A / D converter 320 has a constant distribution by using the image data which is the output of the A / D converter 320. The shutter control signal SHCO is generated. The maximum search window variable circuit 340 calculates the maximum search window and / or the mask window in consideration of the output signal and the motion value of the A / D converter 320. The light amount detector 342 detects the light amount using image data which is an output of the A / D converter 320. The motion speed detector 344 detects the motion speed by using the motion value output from the motion value calculation circuit 350. The maximum search window calculation circuit 346 calculates the size of the maximum search window and / or the mask window in consideration of the light amount and the movement speed output from the light amount detector 342 and the motion speed detector 344. The motion value calculation circuit 350 uses a maximum search window and / or a mask window of the size calculated by the maximum search window calculation circuit 340 to determine a signal output from the A / D converter 320 at a fixed sampling rate. Calculate and output the motion value. The PC interface circuit 360 stores the motion value output from the motion value calculation circuit 360 and transfers the stored motion value to the computer (not shown) at a fixed report rate. Maximum search of the optical pointing system shown in FIG. The operation of the window variable circuit 340 will be described below.

The light quantity detector 342 and the motion velocity detector 344 detect the light quantity and the movement velocity. The maximum search window calculation circuit 346 sets the size of the maximum search window to be small when the amount of light detected by the light quantity detector 342 increases, and sets the size of the maximum search window to a medium size when the amount of light is medium. If less, set the maximum search window size larger. In addition, the maximum search window calculation circuit 346 sets the size of the maximum search window to be small when the movement speed detected by the movement speed detector 344 is high, and sets the size of the maximum search window to the medium size when the movement speed is medium. If the movement speed is slow, set the maximum search window size. At this time, the maximum search window calculation circuit 346 may not only set the size of the maximum search window but also the size of the mask window according to the size of the maximum search window. The maximum search window variable circuit 340 of the optical pointing system of the present invention shown in FIG. 3 varies the size of the maximum search window and / or mask window according to the amount of light and / or the speed of motion, and the motion value calculation circuit 350 The motion value of the image data output from the A / D converter 320 is calculated using the variable maximum search window.

Fig. 4 is a block diagram showing the construction of another embodiment of the optical pointing system of the present invention, including an image sensor 310, an A / D converter 320, a shutter control circuit 330, a motion value calculation circuit 350, and sampling. It consists of the rate variable circuit 370 and the PC interface circuit 360. The sampling rate variable circuit 370 includes a light amount detector 372, a motion speed detector 374, and a sampling rate control circuit 376.

In Fig. 4, the output signal of the sampling rate control circuit 376 is configured to be applied to the shutter control circuit 330, but the output signal of the sampling rate control circuit 376 is not applied to the shutter control circuit 330, but A The output signal of the / D converter 320 may be configured to be applied to the shutter control circuit 330.

The function of each of the blocks shown in FIG. 4 is as follows.

Since the image sensor 310, the A / D converter 320, the light amount detector 372, and the motion velocity detector 374 perform the same functions as the blocks shown in FIG. 3, the function description of FIG. Will be.

The shutter control circuit 330 generates a shutter control signal SHCO in response to the sampling rate control signal SRCO output from the sampling rate control circuit 376, or responds to a signal output from the A / D converter 320. The shutter control signal SHCO may be generated. The exposure time of the electronic shutter (not shown) in the image sensor 310 is controlled by the shutter control signal SHCO generated at this time. The sampling rate control circuit 376 calculates a sampling rate using the amount of light output from the light amount detector 372 and the movement speed output from the motion speed detector 374 to generate a sampling rate control signal SRCO. The motion value calculation circuit 350 calculates a motion value of the image data output from the A / D converter 320 in response to the sampling rate control signal SRCO. The PC interface circuit 360 stores the motion value output from the motion value calculation circuit 350 in response to the sampling rate control signal SRCO and transmits the motion value to a computer (not shown) at a predetermined report rate.

The operation of the sampling rate variable circuit 370 of the optical pointing system shown in FIG. 4 will now be described.

The light amount and the movement speed are detected by the light amount detector 372 and the motion speed detector 374. The sampling rate control circuit 376 adjusts the sampling rate as high as the amount of light increases, adjusts the sampling rate as medium when the amount of light is medium, and adjusts the sampling rate as low as the amount of light decreases. In addition, the sampling rate control circuit 376 increases the sampling rate when the moving speed is high, adjusts the sampling rate to a medium when the moving speed is medium, and decreases the sampling rate when the moving speed is low. Thus, the sampling rate control circuit 376 adjusts the sampling rate in accordance with the light amount and the movement speed.

The operation of the shutter control circuit 330 according to the sampling rate control signal SRCO will be described below.

If the sampling rate control signal SRCO is a signal indicating that the sampling rate is high, the shutter control circuit 330 shortly adjusts the exposure time of the electronic shutter (not shown) in the image sensor 310 and indicates that the sampling rate is about medium. If it is a signal, the exposure time of the electronic shutter (not shown) is adjusted to a medium level, and if it is a signal indicating that the sampling rate is low, the exposure time of the electronic shutter (not shown) is adjusted to be long.

In addition, the shutter control circuit 330 may generate a control signal SHCO for controlling the exposure time of the electronic shutter (not shown) of the image sensor 310 in response to the output signal of the A / D converter 320. In this case, the operation of the shutter control circuit 330 is the same as that of the conventional shutter control circuit 210 shown in FIG.

The sensor circuit of the optical pointing system shown in Fig. 4 can variably adjust the sampling rate according to the amount of light and / or the movement speed, and also variably adjust the exposure time of the electronic shutter (not shown) according to the sampling rate. It is possible.

Fig. 5 is a block diagram showing the construction of another embodiment of the sensor circuit of the optical pointing system of the present invention, in which the sampling rate variable circuit 370 shown in Fig. 3 is replaced by the maximum search window and the sampling rate variable circuit 380. The motion value calculation circuit 350 is replaced with the motion value calculation circuit 350 '. In FIG. 5, the maximum search window and the sampling rate variable circuit 380 include a light amount detector 382 and a motion speed detector ( 384, a maximum search window calculation circuit 386, and a sampling rate control circuit 388. In Fig. 5, although the maximum search window calculation circuit 386 is configured to input all of the light amount detector 382, the motion speed detector 384, and the sampling rate control signal SRCO, the maximum search window calculation circuit is shown. The 386 may be configured to input only a signal output from the light amount detector 382 and the motion speed detector 384 or to input only the sampling rate control signal SRCO.

That is, the sensor circuit of the optical pointing system of FIG. 5 includes all the configurations of the sensor circuits shown in FIGS. 3 and 4. The operation of blocks having the same reference numerals as the blocks shown in FIG. 4 among the blocks shown in FIG. 5 is the same as the operation of the blocks shown in FIG. 5, and the functions of the light quantity detector 382 and the motion speed detector 384 are shown in FIG. The functions are the same as those of the light amount detector 372 and the motion speed detector 374 shown in 4, and the sampling rate control circuit 388 performs the same operation as the sampling rate control circuit 376 shown in FIG.

Therefore, only the function of the maximum search window calculation circuit 386 will be described herein.

The maximum search window calculation circuit 386 calculates the size of the maximum search window and / or the mask window in consideration of the light quantity and the movement speed output from the light quantity detector 382 and the motion velocity detector 384, or the sampling rate control circuit ( The size of the maximum search window and / or the mask window is calculated in response to the sampling rate control signal SRCO output from 388.

The operation of the maximum search window calculation circuit 380 and the sampling rate control circuit 388 of the sensor circuit of the optical pointing system shown in FIG. 5 will be described as follows. The maximum search window calculation circuit 386 is a light quantity detector 382. And adjusting the size of the maximum search window according to the amount of light and the speed of the motion output from the motion speed detector 384 will be described with reference to the above-described operation description. Here, the maximum search window calculation circuit 386 controls the sampling rate. Only the operation of adjusting the maximum search window in response to the signal SRCO will be described. The maximum search window calculation circuit 386 reduces the size of the maximum search window if the sampling rate control signal SRCO is a signal indicating that the sampling rate is high. The maximum search window calculation circuit 386 increases the size of the mask window in response to the sampling rate control signal SRCO. The size of the mask window may vary in proportion to the size of the maximum search window, or may vary in inverse proportion. The method of controlling the sampling rate and the size of the maximum search window may reduce power consumption. It is the same method. For example, as the sampling rate increases, power consumption increases. In this case, by reducing the size of the maximum search window, the amount of signal that the sensor circuit must process is kept constant, and when the sampling rate decreases, power consumption increases. In this case, by increasing the size of the maximum search window, the amount of signal that the sensor circuit must process is kept constant. In addition, the method of controlling the sampling rate and the size of the maximum search window may vary according to the purpose. For example, as described above, the sampling rate and the size of the maximum search window are only used when the optical pointing system is accelerated. Instantaneous fast acceleration can be measured. The sampling rate control circuit 388 controls the sampling rate by varying the sampling rate according to the amount of light and the movement speed output from the light amount detector 382 and the motion speed detector 384. An operation of generating the signal SRCO will be easily understood with reference to the above-described operation description.

The sensor circuit of the optical pointing system of the present invention shown in FIG. 5 is capable of variably adjusting the maximum search window and sampling rate according to the amount of light and / or the speed of movement, and also according to the sampling rate of the electronic shutter (not shown). It is possible to variably adjust the exposure time. That is, the sensor circuit of the optical pointing system of the present invention shown in FIG. 5 can calculate the motion value more accurately than the sensor circuit shown in FIGS. 3 and 4.

Fig. 6 is a block diagram showing the construction of still another embodiment of the sensor circuit of the optical pointing system of the present invention shown in Fig. 5, which is configured by adding a clock control circuit 390 to the sensor circuit shown in Fig. 5.

The function of the clock control circuit 390 shown in FIG. 6 is as follows.

The clock control circuit 390 inputs a reference clock signal CLKR to generate a predetermined number of divided clock signals, and one clock of the predetermined number of divided clock signals in response to the sampling rate control signal SRCO. The sampling clock signal SCLK generated by the clock control circuit 390 shown in FIG. 6 is generated by the shutter control circuit 330 and the maximum search window calculation circuit (SLK). 380, the motion value calculating circuit 350, and the PC interface circuit 360 are applied to perform an operation in response to the sampling clock signal SCLK.

Although not shown, the clock control circuit 390 may be added to the configuration of FIGS. 3 and 4.

Fig. 7 is a block diagram showing the construction of the embodiment of the clock control circuit shown in Fig. 6, which is composed of a clock divider circuit 572 and a multiplexer 574. Figs.

The function of each of the blocks shown in FIG. 7 will be described below.

The clock divider circuit 572 divides the reference clock signal CLKR to generate 32 divided clock signals CLK1 to CLK32. The multiplexer 574 generates one clock signal of the 32 divided clock signals CLK1 to CLK32 as the sampling clock signal SCLK in response to the sampling rate control signal SRCO.

The clock control circuit may be configured as a circuit such as a phase locked loop (PLL) that varies the frequency of the sampling clock signal SCLK in response to the sampling rate control signal SRCO.

8A to 8C illustrate a method of adjusting the maximum search window of the sensor circuit of the optical pointing system of the present invention, wherein the size of the entire window is 32 × 32 and the size of the mask window is fixed to 8 × 8. In this case, a method of adjusting the size of the maximum search window according to the sampling rate or the amount of light and / or the movement speed is described.

8A changes the size of the maximum search window to 14 × 14 when the sampling rate is high or when the amount of light increases and / or the speed of the movement is fast, so that the mask window can be moved up, down, left, and right by 3 pixels. Fig. 8B shows the maximum search window size being 22 × 22 when the sampling rate is medium or when the light amount is medium and / or the speed of movement is medium, so that the mask window can be moved up, down, left and right by 7 pixels. do. 8C changes the size of the maximum search window to 30 × 30 when the sampling rate is low or when the amount of light decreases and / or the movement speed is low, thereby allowing the mask window to move 11 pixels in up, down, left and right.

Since the size of the maximum search window can represent the maximum movement per sample, this value is a variable representing the distance that the optical pointing system can move the maximum per second. For example, when looking for motion at 400 clock per inch (400 cpi), if the sampling rate is 2000 and the maximum search window has 3, the motion of the optical pointing system is (2000sample / second × 3pixel / sample) / (400pixel / inch ) = 15 (inch / second) so that the mouse can be moved up to 15 inches per second. The optical pointing system of the present invention as described above allows the maximum search window and / or sampling rate depending on the amount of light and / or the speed of movement. By varying it is possible to calculate the exact motion value.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

As described above, according to the optical pointing system and the method of calculating the motion value of the system, the maximum search window and / or the sampling rate can be varied according to the amount of light and / or the speed of motion. Therefore, it is possible to find an accurate motion value according to the amount of light and / or the speed of motion.

In addition, according to the optical pointing system and the method of calculating the motion value of the present invention, the power consumption is kept constant and the operating speed is increased by varying the maximum search window and / or the sampling rate.

The motion value calculation method of the present invention can be applied to devices such as an optical mouse, a mobile phone, and a PDA.

Claims (18)

With sensor circuit, The sensor circuit An image sensor configured to generate an analog image signal by detecting light reflected from the surface of the work surface by controlling the exposure level in response to the shutter control signal; An analog / digital conversion circuit configured to convert the analog image signal into a digital image signal and output the converted digital image signal; A shutter control circuit for inputting the digital image signal to generate the shutter control signal; A maximum search window variable circuit configured to input one or more signals of the digital image signal and a motion value to vary a maximum search window size; And And a motion value calculation circuit for calculating the motion value of the digital image signal by using the maximum search window of the variable size. The method of claim 1, wherein the sensor circuit And a sampling rate variable circuit for inputting at least one of the digital image signal and the motion value to generate a sampling rate control signal for varying the sampling rate. The method of claim 2, wherein the sampling rate variable circuit A light amount detector for detecting a light amount by inputting the digital image signal; A motion speed detector configured to detect a motion speed by inputting the motion value input from the motion value calculation circuit; And And a sampling rate calculating circuit configured to generate a sampling rate control signal by calculating a sampling rate according to at least one of the detected light amount and the motion value. The method of claim 3, wherein the shutter control circuit And the shutter control signal is generated by inputting one of the digital image signal and the sampling rate control signal. The method of claim 3, wherein the sensor circuit And an interface circuit configured to store the motion value output from the motion value calculation circuit in response to the sampling rate control signal, and to transmit the motion value to a computer at a predetermined report rate. The method of claim 2, wherein the maximum search window variable circuit And the sampling rate is varied in response to the sampling rate control signal to calculate a maximum search window. The method of claim 2, wherein the motion value calculation circuit And the sampling rate is varied in response to the sampling rate control signal to calculate a motion value. The apparatus of claim 3, wherein the maximum search window variable circuit comprises a maximum search window calculation circuit configured to adjust the size of the maximum search window according to the detected light amount and the movement speed output from the light amount detector and the motion speed detector. Optical pointing system, characterized in that. The method of claim 8, wherein the maximum search window variable circuit And a size of the mask window according to the amount of light and the speed of movement. The method of claim 3, wherein the sensor circuit A division circuit for dividing the reference clock signal to generate clock signals having a predetermined number of different frequencies; And And a clock control circuit having a selection circuit for selecting and outputting one of the clock signals in response to the sampling rate control signal, And the sampling rate is changed in response to one clock signal output from the selection circuit. The method of claim 3, wherein the sensor circuit And a phase locked loop for generating a clock signal for varying the sampling rate in response to the sampling rate control signal. With sensor circuit, The sensor circuit An image sensor configured to generate an analog image signal by detecting light reflected from the surface of the work surface by controlling the exposure level in response to the shutter control signal; An analog / digital conversion circuit configured to convert the analog image signal into a digital image signal and output the converted digital image signal; A shutter control circuit for inputting the digital image signal to generate the shutter control signal; A sampling rate and maximum search window variable circuit for inputting at least one of the digital image signal and a motion value to generate a sampling rate control signal for varying a sampling rate, and for varying the size of the maximum search window; And And a motion value calculation circuit for calculating the motion value of the digital image signal using the variable maximum search window in response to the sampling rate control signal. The method of claim 12, wherein the sampling rate and the maximum search window variable circuit A light amount detector configured to detect an amount of light by inputting an analog image signal input from the image sensor; A motion speed detector configured to detect a motion speed by inputting the motion value input from the motion value calculation circuit; A sampling rate variable circuit for generating the sampling rate control signal for varying a sampling rate in response to at least one of the detected light amount and the movement speed; And And a maximum search window calculation circuit configured to calculate and output a maximum search window in response to at least one of the detected light amount and the movement speed, or in response to the sampling rate control signal. The method of claim 13, wherein the shutter control circuit is And the shutter control signal is generated by inputting one of the digital image signal and the sampling rate control signal. The method of claim 12, wherein the sensor circuit And an interface circuit configured to store the motion value output from the motion value calculation circuit in response to the sampling rate control signal and to store the motion value at a predetermined report rate. Generating an image signal by sensing light reflected from a work surface; A sampling rate and maximum search window variable step of generating a sampling rate control signal for varying a sampling rate by inputting at least one of the image signal and the motion value, and varying the size of the maximum search window; And And a motion value calculating step responsive to said sampling rate control signal and calculating said motion value of said image signal using said variable maximum search window. 17. The method of claim 16, wherein varying the sampling rate and maximum search window A light amount detecting step of detecting a light amount by inputting an image signal input from the image sensor; A motion speed detection step of detecting a motion speed by inputting the motion value; A sampling rate control signal generating step of generating the sampling rate control signal for varying a sampling rate in response to the detected light amount and movement speed; And And a maximum search window calculation step of calculating and outputting a size of the maximum search window in response to the detected light amount and the movement speed, or in response to the sampling rate control signal. 18. The method of claim 17, wherein the step of varying the sampling rate and the maximum search window And a mask window calculation step of calculating and outputting a size of a mask window in response to the detected light amount and the movement speed, or in response to the sampling rate control signal.

Images