KR100883411B1 - Optic pointing device - Google Patents

Abstract

The present invention discloses an optical pointing device. The optical pointing device includes a photocell array including a plurality of photocells that sense light to generate an analog signal corresponding to the light, and an image sensor sequentially outputting analog signals outputted from the plurality of photocells. A comparison unit generating a relative comparison output signal by comparing signals output from the image sensor, and comparing the comparison signal with at least one signal output from the image sensor to generate an absolute comparison output signal and the relative comparison output signal And a controller for outputting motion data using the absolute comparison output signal and outputting a shutter control signal using the absolute comparison output signal. The optical pointing device can reduce the chip size when the A / D converter and the pre-filter circuit, which are conventional components, are implemented as a semiconductor integrated circuit, and remove various offsets by arranging a comparator outside the image sensor. And a correction circuit to obtain high quality image data to obtain accurate motion data of the subject, and to arrange a second photocell separate from the image sensor to generate a shutter control signal in the image processor. This reduces the amount of data computed, reducing the current consumption of the image processor.

Description

Optical pointing device

1 is a block diagram of an example of a conventional optical pointing device.

2 is a block diagram of another example of a conventional optical pointing device.

3 is a view illustrating the image sensor of FIG. 2 in detail.

4 is a block diagram showing the configuration of the optical pointing device of the present invention.

5 is a view showing an optical pointing device according to a first embodiment of the present invention.

6 is a view showing an optical pointing device according to a second embodiment of the present invention.

7 is a block diagram of a relative level comparator to which an offset elimination circuit and an offset correction circuit of the present invention are added.

FIG. 8A illustrates the photocell of FIG. 5 in detail.

8B is a diagram illustrating an example of the offset removing circuit of FIG. 7.

9 is a diagram illustrating an example of an offset correction circuit of FIG. 7.

The present invention relates to an optical pointing device, and more particularly, to obtaining motion data of a subject using an image sensor.

In general, an image sensor is a light conversion device in which a plurality of photocells are arranged. The photocell of the image sensor converts the reflected light of the subject into an electrical signal according to its intensity.

The optical pointing device converts the signals of the photocells, that is, the electrical signals according to the intensity of the reflected light of the subject, into image data of the subject by a series of signal processing, and converts the current and previous image data of the subject. By comparing, the motion data of the subject is calculated and output.

1 is a block diagram of an example of a conventional optical pointing device, which comprises an image sensor 11, an A / D converter 12, a prefilter circuit 13, an image processor 14, and a shutter control circuit 15. It is.

The function of each of the blocks shown in FIG. 1 will be described below.

A light source (not shown) that emits light and a light source control circuit (not shown) that controls the light source illuminate the subject (not shown) by adjusting the amount of emitted light.

The image sensor 11 detects light reflected from an internal pixel array (not shown) to a subject (not shown) and outputs an electrical analog signal PSA corresponding to the amount of light.

The A / D converter 12 receives an electrical analog signal PSA of the image sensor 11 as an input and outputs a digital signal PSAD.

The shutter control circuit 15 receives the output signal PSD of the A / D converter 12 as an input and is composed of a CMOS transistor in the image sensor 11 so that a signal average value of a pixel array (not shown) of the image sensor is constant. A shutter control signal CSH is output for controlling the electronic shutter (not shown) in the image sensor so as to remain at the level.

The prefilter circuit 13 receives the output PSAD of the A / D converter 12 as an input and converts it into a 1-bit structure, i.e., the smallest form of data necessary for motion detection, by a predetermined rule.

In this case, as a rule, an outline detection algorithm or the like is generally used as the rule.

The image processor 14 receives the output signal DSO of the prefilter circuit as an input, calculates motion data of the subject, and outputs the motion data Vk.

As described above, since the conventional optical pointing device shown in FIG. 1 must be provided as the A / D converter 12 and the prefilter circuit 13, the layout of the optical pointing device is the A / D converter 12 and the prefilter. There was a problem that increased as much as the circuit 13, there was a problem that the chip size increases when implemented as a semiconductor integrated circuit.

Fig. 2 is a block diagram of another example of the conventional optical pointing device, which is composed of an image sensor 21, an image processor 24, and a shutter control circuit 25. Figs.

The function of each of the blocks shown in FIG. 2 will be described below.

The image sensor 21 detects light, converts the light into an electrical analog signal corresponding to the amount of light, and outputs the electrical analog signal as a digital signal ISO having a 1-bit structure.

The image processor 24 receives the output signal ISO of the image sensor 21 as an input, obtains motion data of the subject, outputs the motion data Vk, and outputs the shutter data signal as an input signal of the shutter control circuit 25. Input to the IPO and the image sensor 21 outputs a pixel selection signal PS for selecting pixels.

The shutter control circuit 25 receives the shutter data signal IPO of the image processor 24 as an input and is composed of a CMOS transistor in the image sensor 21 so that a signal average value of a pixel array (not shown) of the image sensor 21 is increased. The shutter control signal CSH for controlling the electronic shutter (not shown) in the image sensor 21 to be maintained at a predetermined level is output.

3 is a view illustrating in detail an image sensor of the conventional optical pointing device of FIG. 2. FIG. 3 will be described with reference to FIG. 2.

As shown in FIG. 3, the image sensor 21 of FIG. 2 includes a plurality of unit pixels 36 to 39, and the unit pixel 36 includes a photo cell PC1, a comparator COMP1, and a switch SW1. Consists of

The photocell PC1 receives light and generates an analog voltage corresponding to the amount of light, and the comparator COMP1 responds to the shutter control signal CSH and the output signal PC001 of the photocell PC1 and the adjacent unit pixel ( The output signal PC002 of the photocell PC2 in 37 is compared, and a digital signal COM01 having a 1-bit structure is output.

At this time, the reference voltage of the comparator COMP (N) in the last unit pixel 39 uses an arbitrary reference voltage VREF1.

The switch SW1 outputs the 1-bit digital signal COM01 output from the comparator COMP1 as the output signal ISO of the image sensor 21 in response to the pixel selection signal PS.

Another conventional technology of the conventional optical pointing device as shown in FIG. 1 is an image sensor 21 having a comparator COMP and a switch SW inside the image sensor 21 of the optical pointing device as shown in FIG. 3. ) To solve the problem. However, the image sensor 21 of the optical pointing device shown in FIG. 2 has a limitation in reducing the size of the unit photocell since the comparator COMP and the switch SW are built in the unit photocells 36 to 39. The offset existing for each of the photocells PC1 to PCN of the unit photocells 36 to 39 may not be compensated.

An object of the present invention is to provide an optical pointing device that can reduce the chip size when implemented in a semiconductor integrated circuit.

Another object of the present invention is to provide an optical pointing device having a comparator outside the image sensor and adding an offset removal and correction circuit to obtain a high quality image output and output accurate motion data.

A first embodiment of the optical pointing device of the present invention for achieving the above object comprises a photocell array having a plurality of photocells for sensing light to generate an analog signal corresponding to the light, the plurality of photocells Image sensor sequentially outputting analog signals outputted from the cameras, and comparing the signals output from the image sensor to generate a relative comparison signal, and comparing the comparison signal with at least one signal output from the image sensor and comparing the absolute signal And a controller for outputting motion data using the relative comparison signal and a shutter control signal using the absolute comparison signal.

The image sensor of the optical pointing device of the present invention for achieving the above object is a plurality of photocells arranged in a first direction and a second direction, the plurality of photocells arranged in the first direction in response to a first control signal A photocell line selection circuit for selecting and outputting photocells, and a switch circuit for selecting and outputting analog signals outputted from the plurality of photocells selected by the photocell line selection circuit in response to a second control signal; It is characterized by.

The control unit of the optical pointing device of the present invention for achieving the above object is a motion data output unit for calculating motion data and outputting motion data by inputting the relative comparison signal, and the average value of the signal by receiving the absolute comparison signal And a shutter control signal control unit for outputting a shutter control signal and calculating the first control signal for controlling the photocell line selection circuit of the image sensor and the second control for controlling the switch circuit of the image sensor. It is characterized by outputting a signal.

The comparison unit of the optical pointing device of the present invention for achieving the above object from one or more first comparator for comparing the at least two analog signals output from the switch circuit to output the relative comparison signal, and from the switch circuit And at least one second comparator configured to compare the at least one analog signal to a comparison signal and output the absolute comparison signal.

The comparison unit of the optical pointing device of the present invention for achieving the above object further further comprises an offset correction circuit for correcting the offset of the first comparator itself, and an offset removal circuit for removing the offset of the signal output from the switch circuit. It is characterized by including.

The offset correction circuit of the optical pointing device of the present invention for achieving the above object is characterized by comprising an offset correction circuit of the switched-capacitor type to perform offset correction.

The offset elimination circuit of the optical pointing device of the present invention for achieving the above object is characterized by including an offset elimination circuit of the correlated double sampling method to remove the offset.

A second embodiment of the optical pointing device of the present invention for achieving the above object comprises a photocell array having a plurality of photocells for sensing light to generate an analog signal corresponding to the light, the plurality of photocells Image sensor for sequentially outputting analog signals outputted from the light source, one or more second photocells for sensing light and generating analog signals corresponding to light, and comparing signals outputted from the image sensor A comparator for generating an absolute comparison signal by comparing a signal output from the second photocell with a comparison signal, and outputting motion data using the relative comparison output signal, and using the absolute comparison output signal. And a control unit for outputting a shutter control signal.

The image sensor of the optical pointing device of the present invention for achieving the above object is a plurality of photocells arranged in a first direction and a second direction, the plurality of photocells arranged in the first direction in response to a first control signal A photocell line selection circuit for selecting and outputting photocells, and a switch circuit for selecting and outputting analog signals outputted from the plurality of photocells selected by the photocell line selection circuit in response to a second control signal; It is characterized by.

The control unit of the optical pointing device of the present invention for achieving the above object is a motion data output unit for calculating the motion data and outputs the motion data by inputting the relative comparison signal, and the average value of the signal by receiving the absolute comparison signal And a shutter control signal output unit for outputting a shutter control signal and calculating the first control signal for controlling the photocell line selection circuit of the image sensor and the second control for controlling the switch circuit of the image sensor. It is characterized by outputting a signal.

One or more first comparators for comparing the at least two analog signals output from the switch circuit and outputting a relative comparison signal, and the second photocell of the optical pointing device of the present invention for achieving the above object. And one or more second comparators for outputting an absolute comparison signal by comparing the analog signal and the comparison signal.

The comparison unit of the optical pointing device of the present invention for achieving the above object further comprises an offset correction circuit for correcting the offset of the first comparator itself, and an offset removing circuit for removing the offset of the analog signal output from the switch circuit. It is characterized by further comprising.

The offset correction circuit of the optical pointing device of the present invention for achieving the above object is characterized by comprising an offset correction circuit of the switched-capacitor type to perform offset correction.

The offset elimination circuit of the optical pointing device of the present invention for achieving the above object is characterized by including an offset elimination circuit of the correlated double sampling method to remove the offset.

Hereinafter, an optical pointing device of the present invention will be described with reference to the accompanying drawings.

4 is a block diagram showing the configuration of the optical pointing device of the present invention, which is composed of an image sensor 110, a comparator circuit 130, and an image processor 140. As shown in FIG.

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

A light source (not shown) that emits light and a light source control circuit (not shown) that controls the light source illuminate the subject (not shown) by adjusting the amount of emitted light.

The image sensor 110 detects light reflected from a subject (not shown) and converts the light into an electrical analog signal corresponding to the amount of light. The image sensor 110 generates electrical analog signals (OUT_EVEN, OUT_ODD) generated by a plurality of photocells (not shown). )

The comparator circuit 130 compares the analog signals OUT_EVEN and OUT_ODD output from the image sensor 110 and outputs a relative comparison output signal and absolute comparison output signals OUT_RE and OUT_ABS which are digital signals.

The image processor 140 receives the relative comparison output signal and the absolute comparison output signal OUT_RE and OUT_ABS of the comparator circuit 130 as inputs, obtains and outputs motion data Vk of a subject (not shown), and outputs the image sensor. Generate control signals S-CON, P-CON, and CSH to control 110.

FIG. 5 is a view illustrating an optical pointing device according to a first embodiment of the present invention of FIG. 4, and includes an image sensor 110, a comparator circuit 130, and an image processor 140.

The function of each of the blocks shown in FIG. 5 will be described below.

A light source (not shown) that emits light and a light source control circuit (not shown) that controls the light source illuminate the subject (not shown) by adjusting the amount of emitted light.

The image sensor 110 includes a photocell array 114, a photocell line selection circuit 113, and a switch circuit 112. Each photocell 111 of the photocell array 114 corresponds to the accumulated light amount. Produces an electrical analog signal.

The photocell line selection circuit 113 connects a plurality of photocells in the column line of the photocell array in response to the control signal P-CON of the image processor 140 ( SEL_0A to SEL_NA, SEL_0B to SEL_NB, and open the output lines of the photocells connected to the selected photocell selection line.

The switch circuit 112 selects and outputs two open output lines OUT_0 to OUT_M in response to the control signal S-CON of the image processor 140.

The comparator circuit 130 includes a relative level comparator 131 and an absolute level comparator 132, and the relative level comparator 131 compares two signals OUT_EVEN and OUT_ODD output from the switch circuit 112. A relative comparison output signal OUT_RE of a 1-bit structure is output.

The absolute level comparator 132 compares a comparison signal (a constant level voltage) with a signal output from the switch circuit 112 and outputs an absolute comparison output signal OUT_ABS having a 1-bit structure.

The image processor 140 outputs the control signal P-CON of the photocell line selection circuit 113 and the control signal S-CON of the switch circuit 112, and the motion data output unit 141 and the shutter control. The signal controller 142, the motion data output unit 141 outputs the motion data signal Vk in response to the output signal OUT_RE of the relative level comparator 131, and the shutter control signal controller 142 The shutter control signal CSH for controlling the electronic shutter (not shown) of the image sensor 110 is output in response to the output signal OUT_ABS of the absolute level comparator 132.

In the optical pointing device, although a light source for emitting light and a light source controller for controlling the light source are not illustrated, the image signals of the subjects of the photocells 111 are more received through the light source controller like the shutter control signal controller 142. It can also be output as a clear image signal.

As described above, the operation of the optical pointing device will be described using the function description for each block of the optical pointing device shown in FIG. 5.

The plurality of photocells 111 of the image sensor 110 generates light reflected from a subject (not shown) corresponding to the amount of light.

The photocell line selection circuit 113 in the image sensor 110 outputs a line selection signal in response to the control signal P-CON of the image processor 140 and outputs a plurality of photocell selection lines according to the line selection signal. Two of SEL_0A to SEL_NA and SEL_0B to SEL_NB are selected, and a plurality of photocell output lines OUT_0 to OUT_M connected to the selected photocell selection lines SEL_0A and SEL_0B are opened.

In this case, only one photocell 111 is connected to each photocell output line OUT_0 of the plurality of open photocell output lines OUT_0 to OUT_M to output an analog signal of the photocell 111. The selection of the photocell selection lines SEL_0A to SEL_NA and SEL_0B to SEL_NB may be selected by a prefilter rule, and may be selected randomly or sequentially. The prefilter rule is determined according to the designer's intention, but according to an embodiment of the present invention, the precell rule selects the photocell selection line sequentially. The selected photocell selection lines SEL_0A and SEL_0B are changed to other selection lines SEL_1A and SEL_1B after the output of all photocells selected by the switch circuit 112 is finished. It is obvious that at least two photocell selection lines can be selected by changing the prefilter rule and different wirings between photocells of the photocell array, and selecting only the photocells in the required area by selecting the photocell selection line. Of course it is.

The switch circuit 112 selects all the output lines OUT_0 to OUT_M opened by the line selection signal in response to the control signal S-CON of the image processor 140 {(OUT_0, OUT_1), (OUT_1, OUT_2) .... (OUT_M-1, OUT_M)} to output the analog signals of the photocells, and the switch circuit 112 outputs the analog signals of the photocells of all the selected output lines OUT_0 to OUT_M. Until now, the photocell line selection circuit 113 does not change the selected photocell lines SEL_0A and SEL_0B.

In this case, the selection of the output lines OUT_0 to OUT_M of the switch circuit 112 may be selected by the prefilter rule like the photocell line selection circuit 113, may be randomly selected by the prefilter rule, or sequentially. It may be chosen. The prefilter rule of the switch circuit 112 is determined according to a designer's intention by selecting photocells to be compared, but in the exemplary embodiment of the present invention, two output lines of adjacent photocells are selected and output. Of course, the prefilter rule may be changed and at least two output line selections of the photocell may be selected.

The relative level comparator 131 of the comparator circuit 130 receives two signals OUT_EVEN and OUT_ODD output from the switch circuit 112 as inputs, and compares the relative comparison output signals OUT_RE having a 1-bit structure with each other. Output

At this time, it is natural that the prefilter rule of the switch circuit 112 can be changed to have at least two outputs of the switch circuit 112 and two or more of the relative level comparators 131. In addition, as a specific example of using two or more, it is natural that at least two or more outputs output from the switch circuit 112 can be compared with a specific photocell.

The absolute level comparator 132 of the comparator circuit 130 compares one signal OUT_EVEN of the two signals output from the switch circuit 112 with a comparison signal (a voltage of a constant level), and thus an absolute comparison of the 1-bit structure. Output the output signal OUT_ABS.

At this time, it is natural that the comparison target in the absolute level comparator 132 may be the other output signal OUT_ODD of the switch circuit 112, and the prefilter rule of the switch circuit 112 is changed to switch circuit 112. It is natural that at least two outputs of) and two or more absolute level comparators 132 can be provided.

The motion data output unit 141 of the image processor 140 receives and stores the relative comparison output signal OUT_RE of the relative level comparator 131 as an input. The motion data output unit 141 stores the outputs of all the photocells to form an image of a subject (not shown), calculates the motion data Vk by comparing with a stored previous subject (not shown) image, and calculates The motion data Vk is output.

The shutter control signal controller 142 of the image processor 140 receives and stores the absolute comparison output signal OUT_ABS of the absolute level comparator 132 as an input, calculates an average value of the stored data, and stores the electronics of the image sensor 110. A shutter control signal CSH for controlling a shutter (not shown) is output.

FIG. 6 is a view illustrating an optical pointing device according to a second embodiment of the present invention, and includes an image sensor 110, a comparator circuit 230, and an image processor 140.

The function and operation of each of the blocks shown in FIG. 6 will be described below.

In this case, the image sensor 110 and the image processor 140, which are components that perform the same configuration and operation as those of FIG. 5, are assigned the same numbers as those of FIG. 5, and description thereof will be omitted.

The comparator circuit 230 is composed of a relative level comparator 231 and an absolute level comparator 232, and the relative level comparator 231 compares two signals OUT_EVEN and OUT_ODD output from the switch circuit 112. The relative comparison output signal OUT_RE having a 1-bit structure is output, and the absolute level comparator 62 compares the comparison signal (a constant level voltage) with the output of the second photo cell 233 to output an absolute comparison output signal OUT_ABS. Outputs

In this case, the second photocell 233 received as an input by the absolute level comparator 232 outputs a voltage level corresponding to the amount of incident light as the second photocell 233 for shutter control provided separately from the image sensor 110. do. In addition, the prefilter rule of the switch circuit 112 is changed to have at least two outputs of the switch circuit 112, two or more relative level comparators 231, and two or more second photocells 233. It is obvious that the absolute level comparator 232 may be provided in two or more.

According to the present invention, the A / D converter of the conventional optical pointing device is removed, and the prefilter circuit for generating a digital signal having a 1-bit structure is removed, thereby reducing the chip size when implemented as a semiconductor integrated circuit. In addition, since the shutter control second photocell 233 is provided, the input data calculation amount of the shutter control signal controller 142 for generating the shutter control signal in the image processor 140 is reduced, thereby reducing the current of the image processor 140. Reduce consumption

7 is a block diagram of a relative level comparator with an offset elimination circuit and an offset compensating circuit of the present invention being added, and a relative level comparator with a switching circuit 112, an offset eliminating circuit 335 and an offset compensating circuit 334 ( 330).

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

At this time, the switch circuit 112, which is a component that performs the same configuration and operation as in FIG. 5, is given the same number as in FIG. 5, and description thereof will be omitted.

The relative level comparator 330 to which the offset elimination circuit and the offset correction circuit are added includes a relative level comparator 331, an offset eliminating circuit 335, and an offset compensating circuit 334.

The offset elimination circuit 335 receives the signals OUT_EVEN and OUT_ODD output from the switch circuit 112 as an input and offsets the input signals OUT_EVEN and OUT_ODD using the offset elimination circuit 335 of the correlated double sampling method. And remove the offset-output signals EVEN_R and ODD_R.

The relative level comparator 331 to which the offset correction circuit 334 is added includes a offset-capacitor offset correction circuit 334 to correct its offset, and the offset output from the offset removal circuit 335 is removed. The received signals EVEN_R and ODD_R are input and compared to output a relative comparison output signal OUT_RE having a 1-bit structure.

FIG. 8A illustrates the photocell of FIG. 5 in detail, and the photocell 111 includes a plurality of NMOS transistors M2 to M4 and a photodiode PD.

FIG. 8B is a diagram illustrating an offset elimination circuit of a correlation double sampling method as an example of an offset elimination circuit, in which a plurality of NMOS transistors M5 to M7, a plurality of PMOS transistors M9 to M14, and two capacitors CS and CR are shown. And an operational amplifier BG1.

8A and 8B, the operation of the photocell and the offset removing circuit will be described below.

At the time of initialization, when a reset signal RST of "high" level is applied to the photocell 111, a reset voltage VR is generated at the node TD, and the NMOS transistor M3 is applied to the reset voltage VR. Output the corresponding voltage. When the selection signal SEL_SL of the “high” level is applied, the NMOS transistor M4 is turned on to transmit a voltage corresponding to the reset voltage VR to the output line OUT_0. The output line OUT_0 is output to the input OUT_EVEN of the offset elimination circuit 335 through the switch block 100. Thereafter, when the control signal SR_CON is turned on, the NMOS transistor M6 transmits the input signal OUT_EVEN and charges corresponding to the voltage of the input signal OUT_EVEN are stored in the capacitor CR. At this time, the capacitor CR accumulates charge corresponding to the voltage VR + Voff to which the offset voltage Voff is added to the reset voltage VR.

When the reset signal RST of the "low" level is applied, the shutter (not shown) is turned on, and light is applied to the photodiode PD, the NMOS transistor M2 is turned off, and the photodiode PD is turned on. A current corresponding to the applied light flows, thereby generating a signal voltage Vsig at the node TD. When the selection signal SEL_SL of the "high" level is generated, the NMOS transistor M3 outputs a voltage corresponding to the voltage of the node TD, and the NMOS transistor M4 is turned on to turn on the voltage of the node TD. The voltage corresponding to is transmitted to the output line OUT_0. The output line OUT_0 is output to the input OUT_EVEN of the offset elimination circuit 335 through the switch block 100. After that, when the shutter (not shown) is turned off and the "high" level control signal SS_CON is generated, the NMOS transistor M7 transmits the input signal OUT_EVEN and the input signal OUT_EVEN to the capacitor CS. The charge corresponding to the voltage of is accumulated. At this time, in the capacitor CS, charges corresponding to the voltage Vsig + Voff to which the offset voltage Voff is added to the signal voltage Vsig are accumulated. Thereafter, when the control signals C_CON of the "low" level are applied, the PMOS transistors M9 and M11 are turned on, and the voltage Vsig + Voff applied to the PMOS transistor M10 is applied to the node N1. Is generated, and a voltage corresponding to the voltage VR + Voff applied to the PMOS transistor M12 is generated at the node N2. The operational amplifier BG1 amplifies the difference between these two voltages to generate an output OUT_EVEN_A from which the offset voltage Voff is removed. By performing the operation in this manner, the output OUT_EVEN_A from which the offset by the elements constituting the photocell 111 is removed is generated.

Based on the fact that the signal voltage includes the offset voltage generated by the transistor M3, the offset voltage is common to the offset voltage and the signal voltage, and the offset voltage is subtracted from the signal voltage including the offset voltage. .

9 shows an offset correction circuit of a switched-capacitor type as an example of an offset correction circuit, and is composed of a plurality of switches S1 to S6, a plurality of capacitors C1 to C2, and a comparator BG2.

Referring to the operation of the switched-capacitor offset correction circuit of Figure 9 is as follows.

When the plurality of switches S5 and S6 of the offset correction circuit 334 are turned off and the plurality of switches S1 to S4 are turned on, since no signal is input, the offset voltage Voff of the comparator BG2 only. The output voltage is applied to the nodes P and Q through the switches S3 and S4 that are turned on, and the offset voltage Voff applied to each of the nodes P and Q is applied to the capacitors C1 and S4. C2) stored in each. In this state, when the plurality of switches S5 and S6 are turned on and the plurality of switches S1 to S4 are turned off, the analog signals OUT_EVEN_A and OUT_ODD_A of the nodes A and B are respectively provided. ) Is input, and the signals OUT_EVEN_A + Voff and OUT_ODD_A + Voff to which the offset voltage Voff of the comparator in each of the capacitors C1 and C2 are added to the nodes P and Q are displayed.

The comparator BG2 inputs the signal voltages OUT_EVEN_A + Voff and OUT_ODD_A + Voff shown at the nodes P and Q, compares them, and outputs a relative comparison signal OUT_RE.

In order to compare and output the input signals from the comparator, the offset correction circuit cannot output the comparison signal unless it is higher than the input offset voltage Voff of the comparator. Therefore, the comparison signal is compared by comparing the input signals plus the offset voltage Voff of the comparator. Is a circuit for outputting the capacitor, and a capacitor is used to store the offset voltage (Voff) of the comparator.

The offset double elimination offset circuit and the switched-capacitor offset correction circuit respectively remove or correct an offset. The photocells of the image sensor of the optical pointing device have respective offsets. Due to such offsets, fixed pattern noises are generated, and the fixed pattern noises make the light pointing difficult as the specific gravity increases under a certain amount of light. In addition, the comparator generates an offset due to the non-cracking of the device in the actual circuit configuration, and this offset causes the device to malfunction due to the difference in the input signal in the comparison operation in the comparator. The relative level comparator 331 including the offset elimination circuit 335 and the offset compensating circuit (331) compensates for the above problem and has a low S / N ratio (signal-to-noise ratio) of an optical signal. The optical pointing device operates stably by acquiring a high quality image.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

Therefore, the optical pointing device of the present invention can reduce the area by the area of the A / D converter and the prefilter circuit in the design by removing the A / D converter and the prefilter circuit of the conventional optical pointing device, and implement the semiconductor integrated circuit. In this case, the chip size can be reduced.

In addition, a comparator is provided outside the image sensor to obtain motion data of a subject, and various offset removal and correction circuits are added to obtain high-quality image output to obtain accurate motion data. Having a cell reduces the amount of data computation of the image processor, reducing the current consumption of the image processor and reducing the current consumption of the overall circuit operation.

Claims (14)

An image sensor including a photocell array having a plurality of photocells that sense light to generate an analog signal corresponding to the light, and sequentially outputting analog signals outputted from the plurality of photocells; A comparator configured to generate a relative comparison signal by comparing the signals output from the image sensor, and generate an absolute comparison signal by comparing the comparison signal with at least one signal output from the image sensor; And And a controller for outputting motion data using the relative comparison signal and outputting a shutter control signal using the absolute comparison signal. The method of claim 1, wherein the image sensor A plurality of photocells arranged in a first direction and a second direction; A photocell line selection circuit for selecting and outputting the plurality of photocells arranged in the first direction in response to a first control signal; And And a switch circuit for selecting and outputting an analog signal output from the plurality of photocells selected by the photocell line selection circuit in response to a second control signal. The method of claim 2, wherein the control unit A motion data output unit configured to calculate motion data by outputting the relative comparison signal and output motion data, and a shutter control signal controller to receive the absolute comparison signal, calculate an average value of the signal, and output a shutter control signal; And outputting the first control signal for controlling the photocell line selection circuit of the image sensor and the second control signal for controlling the switch circuit of the image sensor. The method of claim 2, wherein the comparison unit One or more first comparators for comparing the at least two analog signals output from the switch circuit and outputting the relative comparison signals; And And at least one second comparator for comparing the at least one analog signal output from the switch circuit with a comparison signal to output the absolute comparison signal. The method of claim 4, wherein the comparison unit An offset correction circuit for correcting an offset of the first comparator itself; And And an offset removing circuit for removing the offset of the signal output from the switch circuit. The method of claim 5, wherein the offset correction circuit An optical pointing device comprising an offset correction circuit of a switched-capacitor type to perform offset correction. The method of claim 5, wherein the offset elimination circuit An optical pointing device comprising an offset elimination circuit of a correlated double sampling method to remove an offset. An image sensor including a photocell array having a plurality of photocells for sensing light and generating analog signals corresponding to the light, and sequentially outputting analog signals outputted from the plurality of photocells; One or more second photocells that sense light to generate an analog signal corresponding to the light; A comparison unit generating a relative comparison signal by comparing the signals output from the image sensor, and generating an absolute comparison signal by comparing the comparison signal with the signal output from the second photocell; And And a controller for outputting motion data using the relative comparison signal and outputting a shutter control signal using the absolute comparison signal. The method of claim 8, wherein the image sensor A plurality of photocells arranged in a first direction and a second direction; A photocell line selection circuit for selecting and outputting the plurality of photocells arranged in the first direction in response to a first control signal; And And a switch circuit for selecting and outputting an analog signal output from the plurality of photocells selected by the photocell line selection circuit in response to a second control signal. The method of claim 9, wherein the control unit A motion data output unit for calculating motion data and outputting motion data by inputting the relative comparison signal, and a shutter control signal controller for receiving an absolute comparison signal, calculating an average value of the signal, and outputting a shutter control signal; And outputting the first control signal for controlling the photocell line selection circuit of the image sensor and the second control signal for controlling the switch circuit of the image sensor. The method of claim 9, wherein the comparison unit One or more first comparators for comparing at least two analog signals output from the switch circuit and outputting a relative comparison signal; And And at least one second comparator configured to compare an analog signal output from the second photocell with a comparison signal and output an absolute comparison signal. The method of claim 11, wherein the comparison unit An offset correction circuit for correcting an offset of the first comparator itself; And And an offset removing circuit for removing the offset of the analog signal output from the switch circuit. The method of claim 12, wherein the offset correction circuit An optical pointing device comprising an offset correction circuit of a switched-capacitor type to perform offset correction. The method of claim 12, wherein the offset elimination circuit An optical pointing device comprising an offset elimination circuit of a correlated double sampling method to remove an offset.

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