JP4514138B2 - Method for driving solid-state imaging device and digital camera - Google Patents

Description

The present invention relates to a method for driving a solid-state image pickup device and a digital camera , and in particular, to correct the color of a solid-state image pickup device having poor transfer efficiency in a charge transfer path of the solid-state image pickup device to a normal color balance by changing the drive method. The present invention relates to a method for driving a solid-state imaging device and a digital camera .

In recent digital cameras, a CCD (Charge Coupled Device) sensor which is a kind of solid-state image sensor is often used as an image sensor.
The CCD sensor stores a charge according to the amount of incident light, converts a light signal into an electrical signal, a vertical transfer path that receives the charge from the photodiode and sequentially transfers it in the vertical direction, and charges from the vertical transfer path. A horizontal transfer path that sequentially transfers in the horizontal direction and an output amplifier that amplifies the output signal of the horizontal transfer path are provided.

JP 2000-299818

However, in a device (CCD sensor) with poor transfer efficiency in the horizontal transfer path, a phenomenon occurs in which a small amount of charge remains at the final stage of the transfer path and the charge is superimposed on other pixels. In such a device, the color balance may be lost and a color other than the original color may be colored on the screen. This coloring problem is best dealt with on the device side to improve the transfer efficiency.
However, there are variations in devices, and even if device improvements (redesign or retrial) occur after problems occur, it will take time to correct them, and products with fast development speed will respond. I can't.

  Note that Patent Document 1 discloses a method of correcting a variation by providing a mechanism for outputting a reference signal or a dummy signal inside a device with respect to an output variation of a CCD output amplifier. However, Patent Document 1 is not a technique that takes measures against the occurrence of residual charge due to transfer defects in the horizontal transfer path.

  The present invention has been made to solve the above-described problem, and corrects the color of a solid-state image pickup device having poor transfer efficiency in the charge transfer path of the solid-state image pickup device to a normal color balance by changing the driving method. An object of the present invention is to provide a driving method for the solid-state imaging device.

In order to achieve this object, the invention according to claim 1 is characterized in that charges are accumulated for each color pixel (for each RGB) in accordance with the amount of light incident on a solid-state imaging device (for example, a CCD sensor), and an optical signal is converted into an electrical signal. In the solid-state image sensor driving method for driving the solid-state image sensor that sequentially converts the converted charges for each color pixel and outputs the color pixel signal,
When the charges are sequentially transferred and output, if the transfer efficiency is good and the overlap of charge from a predetermined pixel to another pixel is small, the offset amount is small, the transfer efficiency is poor and the predetermined pixel is transferred to another pixel. In this method, the amount of offset is set to be large when the charge superposition is large, and the offset amount is added to the optical black level correction amount to perform subtraction processing .

The above method and the configuration for realizing the method are illustrated in FIGS. 6 and 7A and 7B, for example. In this way, in the case of OB correction with an offset in FIG. 7B, the signal before OB correction is the same as that in FIG. 7A, but the superimposed component is added to the OB component as an offset during OB correction. Then, by subtracting the OB component to which the offset is added, the component superimposed on the signal can be removed.
In addition, when the transfer efficiency of the horizontal transfer path of a CCD sensor, which is an example of a solid-state image sensor, is different, the amount of charge superimposed on other pixels differs, so that a difference occurs in the color balance of the image. Whether the transfer efficiency is good or bad is checked for each CCD sensor, and information about the transfer efficiency is stored in the ROM.
Then, as shown in FIG. 9, according to the information on whether the transfer efficiency is good or bad in the ROM, a small offset is set for a CCD sensor with good transfer efficiency, and a large offset is set for a bad one. In this way, an appropriate offset can be set according to the transfer efficiency of the horizontal transfer path.

  Further, according to the present invention, the problem of a device (for example, a CCD sensor) can be solved by a driving method, and there is no need to redesign or re-prototype the device, resulting in time and cost advantages. This is an effect common to the following claims.

According to a second aspect of the present invention, in the solid-state imaging device driving method according to the first aspect,
The offset amount to be added is set according to the color of the pixel to be subtracted .

  The above method and the configuration for realizing the method are illustrated in FIG. 8, for example. In this way, the color discriminating unit discriminates the color (color) of the pixel to be subjected to OB correction with respect to the CCD signal, and the offset adding unit adds an offset set in advance according to the color to OB. OB correction is performed using the added OB, and RAW data can be brought into a normal color balance.

According to a third aspect of the present invention, in the driving method of the solid-state imaging device according to the first aspect,
The offset amount to be added is constant from the high luminance portion to the middle luminance portion according to the signal amount of the pixel to be subtracted , and is set to be gradually reduced in the low luminance portion .

The above method and the configuration for realizing the method are illustrated in FIGS. 10 to 12, for example.
When the same offset amount is added to the entire screen and subtracted, there is a possibility that the signal is lost in the portion where the signal amount is small due to excessive drawing of the offset. For example, as shown in FIG. 10, if the high luminance part and the low luminance part are subtracted with the same offset in the same screen, the color balance is improved in the high luminance part, but the excessive signal is generated in the low luminance part. Is gone. When the B signal disappears, the blue complementary color is colored yellow, and when the R signal disappears, the magenta complementary color green is colored in the low luminance portion.

Therefore, as shown in FIG. 11, a luminance determining unit and an offset adding unit for adding an offset to the OB value are added, and the luminance determining unit determines the luminance for each pixel with respect to the CCD signal.
The determined brightness is offset by adding an offset to the OB according to the relationship between the brightness and the offset as shown in FIG.
In this way, for example, coloring of the low-luminance portion described above can be prevented.

According to a fourth aspect of the present invention, in the driving method of the solid-state imaging device according to the first aspect,
In the method , the offset amount is set so that the offset amount is large when the gain is large and is small when the gain is small according to the gain of the pixel to be subtracted .

The above method and the configuration for realizing the method are illustrated in, for example, FIGS.
As shown in FIG. 13, when gain is applied, the amount of superimposition of signals superimposed from other pixels increases (shaded area), and the amount of superposition tends to increase as the gain increases. In particular, when the ISO sensitivity is high, the screen is likely to be colored.
Therefore, as shown in FIG. 14, gain determination means and offset addition means for adding an offset to the OB value are added.

The gain determination means adds an offset from the gain applied by AGC according to the relationship between the gain and the offset in FIG.
In this way, for example, coloring of the screen when the ISO sensitivity is high can be prevented.

The invention of claim 5, wherein is a method of a combination of driving how the solid-state imaging device according to any one of claims 2 to 4, and to set the offset amount to the additional.

In this way, "Ru can be RAW data into a normal color balance", "Ru can set an appropriate offset depending on the transfer efficiency of the horizontal transfer path", the coloring of the "low-luminance part the Ru can be prevented ", among the advantages of" Ru can prevent coloring of the screen when the ISO sensitivity is high ", it can be realized by combining at least two effects. According to a sixth aspect of the present invention, charges are accumulated for each color pixel in accordance with the amount of light incident on the solid-state imaging device, and an optical signal is converted into an electrical signal, and the converted charges for each color pixel are sequentially transferred. And it is a digital camera which has a solid-state image sensor output as a color pixel signal, Comprising: It is a digital camera characterized by performing imaging | photography with the drive method of the solid-state image sensor in any one of Claims 1-5.

According to the first aspect of the present invention, the superimposed component is added to the OB component as an offset at the time of OB correction, and the component superimposed on the signal can be removed by subtracting the OB component to which the offset is added. The balance can be corrected.
In addition, according to information on whether transfer efficiency is good or bad in the ROM, a small offset is set for a solid-state imaging device with good transfer efficiency, and a large offset is set for a bad one. In this way, for example, an appropriate offset can be set according to the transfer efficiency of the horizontal transfer path.
Further, according to the present invention, the problem of the device can be solved by the driving method, and it is not necessary to redesign or re-prototype the device, and a time and cost advantage is born. This is an effect common to the following claims.

  According to the second aspect of the present invention, the color discriminating unit discriminates the color of the pixel to be subjected to OB correction with respect to the CCD signal, and the offset adding unit adds an offset preset according to the color to the OB. Since the OB correction is performed using the added OB, the RAW data can be brought into a normal color balance.

According to the third aspect of the present invention, the luminance determining means and the offset adding means for adding an offset to the OB value are added, and the luminance determining means determines the luminance for each pixel with respect to the CCD signal. Then, since the offset is added to the OB according to the relationship between the luminance and the offset and the OB correction is performed on the determined luminance, for example, the above-described coloring of the low luminance portion can be prevented.

According to the fourth aspect of the present invention, the gain determination unit and the offset addition unit for adding an offset to the OB value are added, and the gain determination unit adds the offset according to the relationship between the gain and the offset from the gain applied by the AGC. OB correction. In this way, for example, coloring of the screen when the ISO sensitivity is high can be prevented.

According to the fifth aspect of the present invention, "Ru can be RAW data into a normal color balance", "Ru can set an appropriate offset depending on the transfer efficiency of the horizontal transfer path", "low Ru can be prevented coloration of the luminance portion ", among the advantages of" Ru can prevent coloring of the screen when the ISO sensitivity is high ", a combination of at least two effects, the normal color balance It can be corrected.

Hereinafter, the present invention will be described based on the illustrated embodiments.
First, the configuration and operation of a digital camera used in each embodiment described below will be described.
FIG. 1 is an external view of a digital camera used in each embodiment of the present invention, in which (A) is a top view, (B) is a front view, and (C) is a back view.
FIG. 2 is a block diagram of a control system of the digital camera.

  As shown in FIGS. 1A to 1C, the digital camera DC has a sub LCD (1), a release button (2), and shooting / playback on the upper surface (FIG. (A)) of the camera body BD. And a switching dial (4). The sub LCD (1) is a display unit for displaying, for example, the number of shootable images.

  Further, on the front surface of the camera body BD (FIG. (B)), a strobe light emitting unit (3), a distance measuring unit (5), a remote control light receiving unit (6), a lens barrel unit (7), and an optical viewfinder (Front) (11). (121) is a memory card throttle into which the memory card (130) is inserted, and is provided on the side surface of the camera body BD.

  Furthermore, on the back surface (FIG. (C)) of the camera body BD, AFLED (autofocus LED (8), strobe LED (9), LCD monitor (10), optical viewfinder (back surface) (11b), A zoom button (12), a power switch (13), and an operation unit (14) are provided.

The operation of the digital camera DC will be described with reference to FIGS. 1 (A) to 1 (C) and FIG.
1A to 1C and FIG. 2, a strobe light emitting unit (3) and a strobe circuit (114) are devices that compensate the light amount when light such as natural light is insufficient. When shooting in a dark place or when the subject is dark, a digital flash camera processor (104), which will be described later, transmits a flash emission signal to the flash circuit (114), and the flash circuit (114) emits the flash light emission unit (3). Make the subject brighter.

  The distance measuring unit (5) is a device that measures the distance between the camera and the subject. Currently, a digital camera uses a CCD-AF method in which the contrast of an image formed on an image sensor (CCD) is detected, and the lens is moved to a position with the highest contrast to adjust the focus. However, the CCD-AF method has a problem that the focusing operation is slow because the lens is moved little by little to search for contrast. Therefore, distance information with the subject is always obtained using the distance measuring unit (5), and the lens is moved from the distance information at a stretch to speed up the focusing operation.

  The lens barrel unit (7) includes a zoom lens (7-1a) for capturing an optical image of a subject, a zoom optical system (7-1) including a zoom drive motor (7-1b), a focus lens (7-2a), and a focus. Focus optical system (7-2) composed of drive motor (7-2b), diaphragm (7-3a), diaphragm unit (7-3) composed of diaphragm motor (7-3b), mechanical shutter (7-4a), mechanical It has a mechanical shutter unit (7-4) composed of a shutter motor (7-4b) and a motor driver (7-5) for driving each motor.

The motor driver (7-5) is a CPU block (104) in a digital still camera processor (104), which will be described later, based on input from the remote control light receiving unit (6) and operation input from the operation unit key units (SW1 to SW13). The drive is controlled by the drive command from -3).
The ROM (108) stores control programs and parameters for control described in codes readable by the CPU block (104-3).

When the power of the digital camera DC is turned on, the program is loaded into a main memory (not shown), and the CPU block (104-3) controls the operation of each part of the apparatus according to the program and data necessary for the control. Are temporarily stored in a RAM (107) and a local SRAM (104-4) in a digital still camera processor (104) described later.
By using a rewritable flash ROM as the ROM (108), it becomes possible to change the control program and parameters for control, and the function can be easily upgraded (VerUp).

  The CCD (101) is a solid-state imaging device for photoelectrically converting an optical image, and the F / E (front end) -IC (102) is a CDS (102-1) that performs correlated double sampling for image noise removal. AGC (102-2) for gain adjustment, A / D (102-3) for digital signal conversion, CCD1 control block (104-1), vertical synchronization signal (hereinafter referred to as VD), horizontal synchronization signal (Hereinafter referred to as HD) supplied with a CCD (101) controlled by the CPU block (104-3), and a TG (102-4) that generates a drive timing signal for the F / E-IC (102) Have.

  The digital still camera processor (104) performs white balance setting and gamma setting on the output data of the F / E-IC (102) from the CCD (101), and supplies the VD signal and HD signal as described above. CCD1 control block (104-1), CCD2 control block (104-2) for converting into luminance data / color difference data by filtering processing, CPU block (104-3) for controlling the operation of each part of the device, It has a local SRAM (104-4) for temporarily storing data necessary for the control.

  Furthermore, the digital still camera processor (104) includes a USB block (104-5) for USB communication with an external device such as a personal computer, a serial block (104-6) for serial communication with an external device such as a personal computer, JPEG compression / decompression. JPEG CODEC block (104-7) for performing image processing, RESIZE block (104-8) for enlarging / reducing the size of image data by interpolation processing, and a video signal for displaying image data on an external display device such as a liquid crystal monitor or TV A TV signal display block (104-9) for converting the image data into the image data, and a memory card block (104-10) for controlling the memory card for recording the captured image data.

  The SDRAM (103) temporarily stores image data when the digital still camera processor (104) performs various processes on the image data. The image data to be stored is, for example, taken from the CCD (101) via the F / E-IC (102), and the white balance setting and the gamma setting are performed by the CCD1 signal processing block (104-1). “RAW-RGB image data” in the state, “YUV image data” in which the luminance data / color difference data conversion is performed in the CCD 2 control block (104-2), and JPEG compression in the JPEG CODEC block (104-7) “JPEG image data”.

  The memory card throttle (121) is a throttle for mounting a removable memory card. The built-in memory (120) is a memory for storing captured image data even when no memory card is attached to the memory card throttle (121).

  The LCD driver (117) is a drive circuit that drives an LCD monitor (10), which will be described later, and a signal for displaying the video signal output from the TV signal display block (104-9) on the LCD monitor (10). It also has the function of converting to The LCD monitor (10) is a monitor for monitoring the state of a subject before photographing, confirming a photographed image, displaying image data recorded in a memory card or the built-in memory (120), and the like. is there.

  The video AMP (118) is an amplifier for converting the impedance of the video signal output from the TV signal display block (104-9) to 75Ω, and the video jack (119) is connected to an external display device such as a TV. Jack for. The USB connector (122) is a connector for performing USB connection with an external device such as a personal computer.

  The serial driver circuit (123-1) is a circuit for converting the voltage of the output signal of the serial block (104-6) described above in order to perform serial communication with an external device such as a personal computer. The RS-232C connector ( 123-2) is a connector for serial connection with an external device such as a personal computer.

  The SUB-CPU (109) is a CPU in which ROM and RAM are built in one chip, and the CPU block described above using the output signals of the operation key units (SW1 to SW13) and the remote control light receiving unit (6) as user operation information. (104-3), and the camera status output from the CPU block (104-3) described above, the sub LCD (1), AF LED (8), strobe LED (9), buzzer (described later) 113) and output.

As described above, the sub LCD (1) is a display unit for displaying, for example, the number of images that can be shot, and the LCD driver (111) receives the sub LCD (1) from the output signal of the SUB-CPU (109). ) Drive circuit.
The AF LED (8) is an LED for displaying an in-focus state at the time of photographing, and the strobe LED (9) is an LED for representing a strobe charging state. The AF LED (8) and the strobe LED (9) may be used for another display application such as when a memory card is being accessed.

The operation key unit (SW1-13) is a circuit that receives an input signal from the operation unit (14) operated by the user, and the remote control light receiving unit (6) is a signal reception unit of the remote control transmitter operated by the user. is there.
The sound recording unit (115) includes a microphone (115-3) for inputting a sound signal by a user, a microphone AMP (115-2) for amplifying the input sound signal, and a sound recording circuit (115) for recording the amplified sound signal. 115-1).

  The audio reproduction unit (116) converts an audio reproduction circuit (116-1) that converts a recorded audio signal into a signal that can be output from the speaker, and an audio AMP (116) that amplifies the converted audio signal and drives the speaker. -2) and a speaker (116-3) for outputting an audio signal.

Next, in the digital camera DC configured as described above, a detailed configuration and operation of a main part related in common to each embodiment described below will be described.
<Configuration of CCD sensor>
First, the configuration of the CCD sensor (101) will be described.
FIG. 3 is a schematic diagram of an interline CCD sensor (101) used in a digital camera or the like.

  The CCD sensor (101) has a photodiode (101a) that accumulates charges according to the amount of incident light and converts an optical signal into an electrical signal, and a vertical transfer path that receives charges from the photodiode (101a) and sequentially transfers them in the vertical direction. (101b), a horizontal transfer path (101c) that sequentially transfers charges from the vertical transfer path (101b) in the horizontal direction, and an output amplifier (101d) that amplifies the output signal of the horizontal transfer path (101c). A CCD signal, which will be described later, is output from the output amplifier (101d).

  On the image sensor (CCD sensor (101)), photodiodes (101a) are regularly arranged in a two-dimensional manner, and one photodiode (101a) corresponds to one pixel. One photodiode (101a) is covered with a color filter of one color, and in the primary color CCD sensor (101), RGB color filters are arranged in a color arrangement called a Bayer arrangement as shown in FIG. . In the photodiode, light of a color corresponding to the color filter is accumulated as a charge.

<About OB area>
In general, the CCD sensor (101) has an effective pixel region for capturing a subject image as shown in FIG. 4 and an OB (Optical Black) pixel region so as to surround it. The OB pixel covers the photodiode (101a) with an aluminum film and blocks light from the outside.
Since the photodiode (101a) accumulates charges not only by external light but also by noise such as dark current, the noise component is removed by subtracting the charge of the OB pixel from the charge accumulated in the effective pixel. Such processing is called OB correction. The OB correction may use an average of a plurality of OB pixels.

<About transfer efficiency>
In the case of a normal CCD sensor (101), the electric charge accumulated in the photodiode (101a) is read out to the vertical transfer path (101b), and is directly output from the output amplifier (101d) through the horizontal transfer path (101c). The However, if the transfer efficiency drops at the final stage of the horizontal transfer path (101c) of the CCD sensor (101), the remaining charge is generated in the transfer path, so that the charge is transferred from the pixel with a large charge to the pixel with a small charge. appear.

  As a result, a signal whose color balance is different from the original signal is output. For example, in the case of a primary color CCD sensor, the sensitivity of the G pixel is the highest among RGB, so that more charges are accumulated in the photodiode (101a) of the G pixel than in the R pixel and the B pixel.

FIG. 5 is a diagram showing charges accumulated in one pixel of the G pixel and the R pixel. When the transfer efficiency of the horizontal transfer path (101c) is poor, the horizontal transfer path among the charges accumulated in the G pixel is shown. The portion (shaded portion) where the charge residue in (101c) occurs is superimposed on the R pixel.
Similarly, in the GB line, the charge of the G pixel is superimposed on the B pixel. As a result, the charge amount of R and B increases from the amount of charge that is originally stored, and as a result, the color balance is lost and R and B become dark, so that the entire screen is colored magenta.

Next, each embodiment will be described.
(1) First Embodiment shaped state <offset OB correcting>
A general CCD signal capture will be described with reference to FIG. 2. The signal output from the CCD sensor (101) is subjected to image noise removal by the CDS block (102-1), and is then sent to the AGC block (102-2). Apply gain to the signal. The A / D block (102-3) samples an analog signal for each pixel and converts it into a digital signal. The CCD1 signal processing block (104-1) performs OB correction on the digital signal to remove noise such as dark current components.
The data created here is called RAW data. (Data before OB correction may be called in this way)

  FIG. 6 is a configuration diagram when performing OB correction with an offset added. A function for adding an offset to the OB component when performing OB correction on the output signal (CCD signal) from the CCD sensor (101) is newly added.

FIG. 7 shows the signal amount of one pixel before and after OB correction.
In the conventional OB correction of FIG. 7A, before the OB correction, signal components accumulated by subjecting the light of the subject to photoelectric conversion by the photodiode, OB components generated by dark current, and transfer defects in the horizontal transfer path. A superimposed component superimposed from another pixel is a signal. Since only the OB component is subtracted by the OB correction, the superimposed component remains in the signal.

  In the case of OB correction with an offset in FIG. 7B, the signal before the OB correction is the same as in FIG. 7A, but at the time of OB correction, the superimposed component is added as an offset to the OB component, and the offset is added. By subtracting the OB component, the superimposed component can be removed from the signal.

(2) In the second embodiment shaped state this embodiment, newly with offset adding means for adding an offset to the means and OB value to color discrimination.
The inside of the dotted line in FIG. 8 is a newly added part. For the CCD signal, the color discrimination means discriminates the color of the pixel to be subjected to OB correction. The color discrimination method is based on the line identification pulse signal output from the CCD, or the vertical sync signal (VD) and horizontal sync signal (HD) are counted in the digital still camera processor (104) to specify the color. May be.
The offset adding means adds an offset set in advance according to the color to OB. Then, OB correction is performed using the OB to which the offset is added, and the RAW data is brought to a normal color balance.

(3) <about the differences between transfer efficiency> third preferred form state
When the transfer efficiency of the horizontal transfer path (101c) of the CCD sensor (101) is different, the amount of charge superimposed on other pixels is different, so that a difference occurs in the collapse of the color balance of the image. For example, when an equivalent offset is added to ones with different transfer efficiencies, the offset added to the OB amount may be optimal. However, in many cases, the offset is too large or too small, or the offset is too small. A shortage occurs.

When excessive drawing occurs, the image that has been colored magenta is colored green in the complementary color direction of magenta. On the contrary, when it is not enough, the overlapped portion still remains, so that the magenta coloring degree becomes light but remains colored. Therefore, it is necessary to vary the offset value according to the transfer efficiency.
Whether the transfer efficiency is good or bad needs to be inspected for each CCD sensor (101). Here, the inspection method is omitted, but information on the quality of transfer efficiency is held in the ROM (108). Suppose that

FIG. 9 is a graph showing the transfer efficiency and the offset amount. It is assumed that the horizontal axis indicates the transfer efficiency and the transfer efficiency decreases as it goes to the right.
As shown in FIG. 9, a small offset is set for a CCD (101) with good transfer efficiency and a large offset is set for a bad one according to information on whether transfer efficiency is good or bad in the ROM (108).

(4) <Differences in signal amount> the fourth exemplary form status
When the same offset amount is added to the entire screen and subtracted, there is a possibility that the signal is lost in the portion where the signal amount is small due to excessive drawing of the offset.

  FIG. 10 is a diagram showing a case where the same offset is added in the high luminance part and the low luminance part. The hatched portion is an offset portion, and R and B are subtracted from the original signal by the same amount. When subtraction is performed with the same offset in the high luminance portion and the low luminance portion in the same screen, the color balance is improved in the high luminance portion, but excessive drawing occurs in the low luminance portion, and the B signal is lost. When the B signal disappears, the blue complementary color is colored yellow, and when the R signal disappears, the magenta complementary color green is colored in the low luminance portion.

In view of this, in the present embodiment, there are newly provided luminance determination means and offset addition means for adding an offset to the OB value. The inside of the dotted line in FIG. 11 is a newly added portion. With respect to the CCD signal, the luminance determining means determines the luminance for each pixel.
The determined brightness is offset by adding an offset to the OB according to the relationship between the brightness and the offset as shown in FIG. A constant offset is set from the high luminance part to the medium luminance, and a small offset is set step by step in the low luminance part to suppress excessive drawing.

(5) <place with low before the signal amount applying a gain> fifth embodiment shaped state
FIG. 13 is a diagram illustrating the signal amount before applying the gain and the signal amount after applying the gain. The hatched portion is a signal superimposed from other pixels, and the overlap is increased by applying a gain. Thus, as the gain increases, the amount of superposition tends to increase.

In particular, when the ISO sensitivity is high, the exposure time is short and the amount of signal accumulated in the photodiode (101a) is small. In order to create an image by applying a large gain to the small signal, the screen is colored. Likely to happen.
In view of this, in the present embodiment, gain determination means and offset addition means for adding an offset to the OB value are newly provided. The inside of the dotted line in FIG. 14 is a newly added portion.

The gain determination means adds an offset from the gain applied by AGC according to the relationship between the gain and the offset in FIG.
Since the gain applied to the image is uniformly applied in the screen except for special cases, a small offset is set when the gain is low, and a large offset is set when the gain is high.

  The case where a CCD sensor is used as an embodiment of the present invention has been described. However, charges are accumulated for each color pixel in accordance with the amount of light incident on the solid-state imaging device, optical signals are converted into electrical signals, and the converted charges for each color pixel are sequentially transferred and output as color pixel signals. Of course, the present invention can be applied to any solid-state imaging device.

BRIEF DESCRIPTION OF THE DRAWINGS It is an external view of the digital camera used by each embodiment of this invention, (A) is a top view, (B) is a front view, (C) is a back view. It is a block diagram of a control system of the digital camera. It is a schematic diagram of the interline type CCD sensor of the digital camera. It is a figure which shows the effective pixel area | region and OB pixel area | region in the CCD sensor. In the CCD sensor, it is a conceptual diagram showing a state in which a portion (shaded portion) in which charges remain in the horizontal transfer path among charges accumulated in G pixels is superimposed on R pixels. It is a figure which shows 1st embodiment of this invention, Comprising: It is a block diagram in the case of adding OB and performing OB correction. FIG. 4 is a diagram illustrating a signal amount of one pixel before and after OB correction in the first embodiment, where (A) is a case of conventional OB correction and (B) is a case of OB correction with an offset added. It is. It is a figure which shows the 2nd embodiment, Comprising: It is a block diagram in the case of performing color setting and offset setting. It is a figure which shows the relationship between transfer efficiency and offset amount in 3rd embodiment. It is a figure which shows the case where only the same offset is added in the high-intensity part and the low-intensity part in the same 4th embodiment. It is a figure which shows the 4th embodiment, Comprising: It is a block diagram in the case of performing brightness | luminance determination and offset setting. It is a figure which shows the relationship between a brightness | luminance and an offset in the 4th embodiment. It is a figure which shows the signal amount before applying a gain, and the signal amount after applying a gain in the fifth embodiment. It is a figure which shows the said 5th embodiment, Comprising: It is a block diagram in the case of performing the offset setting according to gain. It is a figure which shows the relationship between a gain and an offset in the same 5th embodiment.

Explanation of symbols

DC digital camera BD camera body SW1 to SW13 Operation unit Key unit 1 Sub LCD
2 Release button 3 Strobe light emitting unit 4 Shooting / playback switching dial 5 Ranging unit 6 Remote control light receiving unit 7 Lens barrel unit 7-1 Zoom optical system 7-1a Zoom lens 7-1b Zoom drive motor 7-2 Focus optical system 7- 2a Focus lens 7-2b Focus drive motor 7-3 Aperture unit 7-3a Aperture 7-3b Aperture motor 7-4 Mechanical shutter unit 7-4a Mechanical shutter 7-4b Mechanical shutter motor 7-5 Motor driver 8 AFLED (autofocus LED )
9 Strobe LED
10 LCD monitor 11a Optical viewfinder (front)
11b Optical viewfinder (back side)
12 Zoom button 13 Power switch 14 Operation unit 101 CCD
102 F / E (front end) -IC
102-1 CDS
102-2 AGC
102-3 A / D
102-4 TG
103 SDRAM
104 Digital still camera processor 104-1 CCD1 control block 104-2 CCD2 control block 104-3 CPU block 104-4 Local SRAM
104-5 USB block 104-6 Serial block 104-7 JPEG CODEC block 104-8 RESIZE block 104-9 TV signal display block 104-10 Memory card block 107 RAM
108 ROM
109 SUB-CPU
111 LCD Driver 113 Buzzer 115 Audio Recording Unit 115-1 Audio Recording Circuit 115-2 Microphone AMP
115-3 Microphone 116 Audio reproduction unit 116-1 Audio reproduction circuit 116-2 Audio AMP
116-3 Speaker 117 LCD Driver 118 Video AMP
119 Video jack 120 Internal memory 121 Memory card throttle 122 USB connector 123-1 Serial driver circuit 123-2 RS-232C connector 130 Memory card

Claims (6)

Solid-state imaging that accumulates charge for each color pixel according to the amount of light incident on the solid-state image sensor, converts an optical signal into an electrical signal, sequentially transfers the converted charge for each color pixel, and outputs it as a color pixel signal In a method for driving a solid-state imaging device for driving an element,
When the charges are sequentially transferred and output, if the transfer efficiency is good and the overlap of charge from a predetermined pixel to another pixel is small, the offset amount is small, the transfer efficiency is poor and the predetermined pixel is transferred to another pixel. A method of driving a solid-state imaging device, characterized in that an offset amount is set to be large when charge superposition is large, and the offset amount is added to an optical black level correction amount to perform subtraction processing . The solid-state imaging device driving method according to claim 1,
A method of driving a solid-state imaging device, wherein the offset amount to be added is set according to the color of a pixel to be subtracted . The solid-state imaging device driving method according to claim 1,
The solid-state imaging device characterized in that the offset amount to be added is set to be constant from a high luminance portion to a middle luminance portion according to a signal amount of a pixel to be subtracted and gradually reduced in a low luminance portion. Driving method. The solid-state imaging device driving method according to claim 1,
The solid-state imaging device driving method, wherein the offset amount is set to be large when the gain is large and small when the gain is small , according to the gain of the pixel to be subtracted. Method. By combining the drive how the solid-state imaging device according to any one of claims 2 to 4, the method for driving the solid-state imaging device is characterized in that so as to set the offset amount to the additional. Solid-state imaging that accumulates charge for each color pixel according to the amount of light incident on the solid-state image sensor, converts an optical signal into an electrical signal, sequentially transfers the converted charge for each color pixel, and outputs it as a color pixel signal A digital camera having an element,
A digital camera that performs photographing by the method for driving a solid-state imaging device according to claim 1.

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