KR20070070467A - Image sensor having storage means and method for generating image data using the same - Google Patents

Abstract

An image sensor including storage elements and a method for generating image data by using the image sensor are provided to prevent a rolling shutter effect and image distortion by adding storage element to image pixels of the image sensor. An image sensor includes a plurality of image pixels. Each of the image pixels includes a light-receiving element(301) for receiving light reflected from an object and generating charges corresponding to the light, a storage element(303) for storing the charges generated by the light-receiving element, a first switch(305) for initializing the light-receiving element, a second switch(307) for initializing the storage element, a third switch(309) for controlling the charges generated by the light-receiving element to be transferred to the storage element, and a fourth switch(311) for controlling the charges stored in the storage element to be transferred to the outside of the image pixels.

Description

Image sensor having storage means and method for generating image data using the same}

1 is a view showing the configuration of a conventional image sensor,

2 is a view showing a distortion of an image that appears when using a rolling shutter method;

3 is a view illustrating a configuration of an image pixel unit of a pixel array unit of an image sensor according to an exemplary embodiment of the present invention;

4 is a flowchart illustrating an operation procedure of an image pixel unit of a pixel array unit of an image sensor;

5 is a view showing the flow of charge when the storage body is a photodiode,

6 is a view for explaining the operation of the photogate used in the preferred embodiment of the present invention,

7 is a view illustrating an image pixel unit using a photogate according to an exemplary embodiment of the present invention;

8 is a view illustrating an operation of an image pixel unit using a photogate as a storage body according to an exemplary embodiment of the present invention;

9 is a view showing an effect compared to the conventional rolling shutter method when using the image pixel unit according to an embodiment of the present invention.

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

301... Light receiver, 303... Reservoir,

305... First switch, 307... Second switch,

307... Second switch, 309... Third switch,

311... Fourth switch.

The present invention relates to an image sensor including a storage body and a method of generating image data using the same, comprising: an image sensor capable of preventing a rolling shutter effect by providing a storage body in an image pixel portion of a pixel array unit constituting the image sensor; It relates to a method of generating image data using the same.

An image sensor refers to a device that generates a digital image signal for a subject by receiving light reflected from the subject and generating an electrical signal corresponding thereto. Such an image sensor generates an image signal by using a photo diode to generate a charge corresponding to light received from a subject and to detect the generated charge.

Such an image sensor typically includes a pixel array unit in which an image pixel portion composed of a photodiode, a transistor, etc. is arranged in a plurality of rows and columns, and the pixel array portion is selected by a row signal selector or a column signal selector, Image signals are sequentially generated in units of columns.

1 is a view showing the configuration of such a conventional image sensor.

Referring to FIG. 1, a conventional image sensor includes a pixel array unit 101, a row signal selector 103, an analog signal detector 105, a column signal converter 107, and a column signal selector 109. do.

The pixel array unit 101 receives light reflected from a subject and generates corresponding charges. The pixel array unit 101 generally includes an image pixel unit composed of a plurality of rows and columns, and each image pixel. The unit 111 is composed of a photodiode, a transistor, and the like, respectively.

The row signal selector 103 controls to select each image pixel part 111 constituting the pixel array part 101 on a row basis, and the column signal selector 109 constitutes the pixel array part 101. Each image pixel unit 111 is controlled to be selected in units of columns.

The analog signal detector 105 is a portion that detects the charge generated in each of the image pixel units 111 transmitted from the pixel array unit 101. Each of the image pixel units 111 is connected to the analog signal detector 105 in units of columns, so that charges generated in the image pixel units 111 existing in each column of the row selected by the row signal selector 103 are converted into analog signals. It may transmit to the detector 105.

In addition, the column signal converter 107 converts the charge detected by the analog signal detector 105 into a digital signal.

In the conventional image sensor having such a configuration, the row signal selection unit 103 operates sequentially from the image pixel unit 111 belonging to the first row of the image arranging unit 101. At this time, the charge generated by the signal received by the image pixel part 111 belonging to the first row must be detected and converted by the analog signal detector 105 and the column signal converter 107 so that the image pixel part belonging to the next row Since the 111 can be operated, a time interval occurs between the time when the first row is selected and the time when the next row is selected. As a result, when the subject moves or the digital imaging device shakes, the distortion of the image may occur. Occurs. This is called a rolling shutter method.

FIG. 2 is a diagram illustrating distortion of an image that appears when using such a rolling shutter method, and illustrates distortion of an image that appears when a subject moves to the right when generating image data of consecutive frames in an image sensor having six rows. . This is because, as described above, the pixel array unit 101 sequentially detects and converts charges in units of rows, and thus the image of the subjects is distorted in units of rows as the subject moves to the right.

In the conventional image sensor and the rolling shutter method, when generating image data of one frame, the exposure is changed in units of rows as the pixel array units of the image sensor are sequentially operated, and the time for detecting and converting the image data is changed. Accordingly, there is a problem that the image is distorted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides an image sensor capable of preventing a distortion of an image by solving a rolling shutter problem by providing a storage body in a plurality of image pixel portions constituting an image sensor. For the purpose of

According to an aspect of the present invention, there is provided an image sensor including a pixel array unit including a plurality of image pixel units, wherein each image pixel unit receives light reflected from a subject and receives a corresponding charge. A light receiving body to be generated, a storage body storing charges generated by the light receiving body, a first switch to initialize the light receiving body, a second switch to initialize the storage body, and control to transfer charges generated from the light receiving body to a storage body A third switch and a fourth switch for controlling to transfer the charge stored in the storage to the outside of the pixel array unit provides an image sensor.

Here, the light receiver is a photodiode, and the storage body is a photogate.

In addition, when the charge is transferred to the outside of the pixel array unit by the fourth switch, the photogate may be configured to change the voltage level of the photogate and then transmit the charge.

In addition, the first switch, the second switch, the third switch, and the fourth switch may be transistors.

In an exemplary embodiment, all the image pixel parts of the pixel array part may be configured to operate simultaneously.

The image sensor may further include a row signal selection unit for selecting a row of the pixel array unit, an analog signal detector for detecting a signal corresponding to the charge stored in the image pixel unit of the pixel array unit, and a conversion from the analog signal detector And a column signal selector for converting the analog signal into a digital signal, and a column signal selector for selecting a column of the pixel array unit, wherein the signal detected by the analog signal detector is controlled by the charge transmitted from the storage body. It can be configured to correspond.

Further, according to another aspect of the present invention, an image sensor including a pixel array unit having a plurality of image pixel units, wherein each image pixel unit of the pixel array unit receives light reflected from a subject to generate a corresponding charge. And a light receiving body, and a storage body storing charges generated by the light receiving body.-A method of generating image data in a sensor, the method comprising: receiving light reflected from a subject in the light receiving body to generate a corresponding charge; And storing the charges generated by the light-receiving member in a storage body and transferring the charges stored in the storage body to an outside of the pixel array unit.

Here, the light receiving body is a photodiode, and the storage body is preferably a photogate.

In addition, when the charge is transferred to the outside of the pixel array unit, the photogate may be transferred after changing the voltage level of the photogate.

In addition, all the image pixel units of the pixel array unit may operate simultaneously.

Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a configuration of an image pixel unit of a pixel array unit of an image sensor according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the image pixel portion of the pixel array of the image sensor of the present embodiment is a light receiving member 301, a storage body 303, a first switch 305, a second switch 307, and a third switch 309. And a fourth switch 311.

The light receiver 301 is responsible for receiving light reflected from a subject and generating a corresponding charge. In general, a photodiode is mainly used as the light receiver 301 in the image sensor.

The storage body 303 plays a role for storing the electric charges generated by the light receiving body 301. As the storage body 303, a photogate, a photodiode, and a general capacitor may be used. This is because when the photodiode or capacitor is used as the storage body 303, all of the charges generated by the light receiver 301 may not be stored in the storage body 303. Detailed description thereof will be described later with reference to FIG. 5.

The first switch 305 initializes the light receiver 301 to empty unnecessary charges remaining in the light receiver 301. When the first switch 305 is operated, all of the charge remaining in the light receiver 301 flows out along the first switch 305, so that unnecessary charge remains in the light receiver 301.

The second switch 307 is a switch for emptying the remaining unnecessary charges by initializing the storage body 303. The second switch 307 may be configured after the charge stored in the storage body 303 is transferred to the analog signal detector. When operated, all of the charge remaining in the storage body 303 unnecessarily flows out along the third switch 307, so that unnecessary charge does not remain in the storage body 303, thereby transferring charges transmitted from the light receiver 301. You can save it again.

The third switch 309 is a switch that connects the light receiver 301 and the storage 303. When the light receiver 301 receives the light reflected from the subject and generates a corresponding charge, the generated charge must be transferred to the storage body 303. At this time, the third switch 309 operates, whereby the light receiver 301 The charge generated in) is transferred to the storage body 303. Although the third switch 309 may use a transistor in the present invention, it is preferable to use a photogate to receive all of the charges generated by the light receiver 301.

The fourth switch 311 is responsible for transferring charges stored in the storage body 303 to an analog signal detector connected to the image pixel unit. That is, when the charge received from the light receiver 301 is stored in the storage 303, the fourth switch 311 operates to transfer the charge stored in the storage 303 to the analog signal detector.

FIG. 4 is a flowchart illustrating an operation sequence of an image pixel unit of the pixel array unit of the image sensor described with reference to FIG. 3.

Referring to FIG. 4, first, the first switch 305 and the second switch 307 are operated (step 401), and thus the light receiver 301 and the storage body 303 are initialized (step 403). This is a preliminary work to remove unnecessary charges present in the light receiver 301 and the reservoir 303 before generating and storing the charge.

Next, the light receiver 301 is charged to generate electric charges according to the light drawn from the outside (step 405). As soon as charging of the light receiver 301 is completed and charge generation is completed, the third switch 309 is operated (step 407), and the charges charged to the light receiver 301 along the third switch are stored by the voltage difference. Go to 303 (step 409). Through this process, the charges generated by the light receiver 301 are transferred to the storage body 303 and the storage body 303 is charged (step 411).

The third switch is again cut off (step 413), and by the operation of the fourth switch 311 (step 415), the charge stored in the storage body 303 is transmitted to the analog signal detector (step 417).

FIG. 5 is a diagram illustrating a flow of electric charges when the storage body of FIG. 3 is a photodiode, and illustrates only the relationship between the light receiving body 301, the storage body 303, and the third switch 309 in the image pixel unit.

First, reference numeral 511 is a diagram in which the light receiver 301 charges a charge in the image pixel unit. At this time, as can be seen by reference numeral 521, the charge of the light-receiving member 301 is filled and the charge of the storage body 303 shown next to it is empty.

Thereafter, when the third switch 309 operates as shown by reference numeral 513, as shown by reference numeral 523, the voltage between the light receiver 301 and the storage body 303 becomes equal to the light receiver 301. Charge charged in the flows into the storage body (303).

Then, when the third switch 309 is blocked again, as shown at 515, the light receiver 301 and the reservoir 303 are electrically separated as shown at 525. At this time, as can be seen at reference numeral 521, the charge generated in the light receiver 301 is compared with the amount of charge initially stored in the light receiver 301 and the amount of charge stored in the storage body 303 which can be checked at reference numeral 525. It can be seen that both are not transmitted to the storage body 303. This is because both the light receiver 301 and the storage 303 are photodiodes, and the voltage reference is the same, so even when the third switch 309 is connected, all the charges of the light receiver 301 are not transferred to the storage 303. Is a phenomenon that occurs. In order to solve this problem, in the present invention, it is preferable to use a photogate instead of a photodiode or a capacitor.

6 is a view for explaining the operation of the photogate used in the preferred embodiment of the present invention.

The photogate is characterized by transferring charge by varying the voltage reference as described below. 6 is a view illustrating a case in which a photogate serves as a storage body. First, a charge is charged in the photogate as shown by reference numeral 611. Thereafter, when the reset signal 605 is input, the voltage reference of the reset signal portion is lowered as shown by reference numeral 613. Next, when the bias signal 601 and the transfer gate signal 603 are transmitted, as shown by reference numeral 615, the voltage reference of the photogate increases and the voltage reference of the transfer gate decreases to naturally charge the photogate. After the transfer of the bias signal 601 and the transfer gate signal 603 is completed, the charge is transferred to the transfer gate, and the voltage reference of the photogate and the voltage reference of the transfer gate are returned to their original positions, thereby transmitting the row selection signal 607. The charge flows outward.

Such a photogate has an advantage of high conversion gain since no charge remains in the photogate after the charge is transferred. By using this advantage it is possible to use a photogate instead of a photodiode as a storage body according to the present invention.

7 is a diagram illustrating an image pixel unit using a photogate according to an exemplary embodiment of the present invention.

Referring to FIG. 7, each part of the figure corresponds to each part of FIG. 3. That is, the light receiver 701, the storage body 705, the first switch 707, the second switch 709, the third switch 703, and the fourth switch 711, which are described with reference to FIG. 3, respectively. Since it corresponds to a structure, the duplicate description is abbreviate | omitted about the same structure.

In FIG. 7, a photodiode is used as the light receiver 701. The photodiode is a device used as the light receiver 701 in a general image sensor, and receives a light signal to generate a corresponding charge.

A photogate is used as the storage body 705. As illustrated in FIG. 6, since the photogate has a higher conversion gain than the photodiode, the charge that may occur when the photodiode is used as a storage material does not move.

The third switch 703 also uses a photogate. Although this will be described in detail with reference to FIG. 8, the charge charged in the photodiode 701, which is a light receiver, is completely transferred to the photogate 705, which is a storage body.

The third switch 703 also includes a first transfer gate signal line 713, a bias signal line 715, and a second transfer gate signal line 717 for changing the voltage level of the storage body 705 to control the signal lines. By transmitting a signal, the charge generated in the photodiode 701 is transferred.

The operation of the image pixel unit configured as described above will be described in detail with reference to FIG. 8.

8 is a view illustrating an operation of an image pixel unit using a photogate as a storage body according to an exemplary embodiment of the present invention.

7 and 8, charge is first charged to the photodiode 701 as shown by reference numeral 801. Thereafter, when a signal is input from the first transfer gate signal line 713, as shown by reference numeral 803, the voltage reference of the third switch is lowered to transfer charges charged in the photodiode 701 to the photogate 705. After that, when the control signal is returned to the previous state in the first transfer gate signal line 713, the voltage reference of the third switch is returned and all the charges charged in the photodiode 701 are transferred to the photogate 705. Thereafter, as shown in reference numerals 807 and 809, when the control signal flows into both the bias signal line 715 and the second transfer gate signal line 717, as shown in FIG. 6, the voltage reference is inverted to maintain the charge remaining in the photogate. All will flow outside.

9 is a view showing an effect compared to the conventional rolling shutter method when using the image pixel unit according to an embodiment of the present invention.

Referring to FIG. 9, when the camera moves to the left side or the object moves to the right side, the conventional image sensor has a distortion in which an image is captured in a diagonal shape in which a subject is extended to the right as shown by reference numeral 901. This is a phenomenon caused by the fact that each row of the image sensor is sequentially operated as described above, and thus the timing of acquiring an image signal by generating and detecting charges is different for each row. It was a structural problem of the image sensor that occurred because there was no space to store the generated charges after entering.

On the other hand, in the case of using an image sensor including an image pixel unit having a storage body according to the present invention, if there is a storage body around the light receiving body, charges generated by the light receiving body can be stored in the storage body, thereby forming one frame. Each image pixel unit of the image sensor may be operated at the same time. That is, when the image pixel parts are all operated at the same time and the electric charges generated in the storages provided in the image pixel parts are stored, the image pixel parts are sequentially detected to acquire the entire image data constituting one frame without generating digital image data. Therefore, as shown by reference numeral 911, even a moving subject can acquire accurate image data without distortion of the screen.

According to the present invention, by providing a storage body in a plurality of image pixel units constituting the image sensor, it is possible to provide an image sensor capable of solving the rolling shutter problem to prevent distortion of the image.

In addition, according to the present invention, when the photogate is used as the storage body in the image pixel portion, the generated charges can be transferred completely, thereby increasing the conversion gain.

Claims (12)

An image sensor comprising a pixel array unit having a plurality of image pixel units, Each image pixel portion of the pixel array portion, A light receiver configured to receive light reflected from a subject and generate a corresponding charge; A storage unit storing charges generated by the light receiver; A first switch for initializing the light receiver; A second switch for initializing the storage body; A third switch for controlling the charge generated by the light receiver to be transferred to a storage body; And A fourth switch for controlling the charge stored in the storage to be transferred outside the pixel array unit Image sensor comprising a. The method of claim 1, The light receiver is an image sensor, characterized in that the photodiode. The method of claim 1, And the storage body is a photogate. The method of claim 3, The photogate transfers the voltage after changing the voltage level of the photogate when the charge is transferred to the outside of the pixel array by the fourth switch. The method of claim 1, And the first switch, the second switch, the third switch and the fourth switch are transistors. The method of claim 1, And all image pixels of the pixel array unit operate simultaneously. The method of claim 1, The image sensor, A row signal selector for selecting a row of the pixel array; An analog signal detector for detecting a signal corresponding to the charge stored in the image pixel portion of the pixel array portion; A thermal signal converter converting the analog signal converted by the analog signal detector into a digital signal; And A column signal selection unit for selecting a column of the pixel array unit Include more, And a signal detected by the analog signal detector corresponds to a charge transmitted from the storage body. An image sensor including a pixel array unit having a plurality of image pixel units, wherein each image pixel unit of the pixel array unit receives a light reflected from a subject and generates a corresponding charge; A storage medium for storing an electric charge, the method comprising:-generating image data in a sensor, the method comprising: Receiving light reflected from a subject in the light receiver and generating a corresponding charge; Storing the charge generated in the light receiver in a storage body; And Transferring charges stored in the storage to the outside of the pixel array; Image data generation method comprising a. The method of claim 8, And the light receiver is a photodiode. The method of claim 8, And the storage body is a photogate. The method of claim 10, And transmitting the photogate after changing the voltage level of the photogate when transferring charge to the outside of the pixel array unit. The method of claim 8, And all image pixel portions of the pixel array portion are operated simultaneously.

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