CN1798273A - Image sensing apparatus and image sensing apparatus control method - Google Patents

Abstract

The present invention provides an image pickup device and a control method of the image pickup device having a solid-state imaging element (14), wherein the solid-state imaging element (14) is configured by arranging a plurality of pixels including photoelectric conversion elements in a matrix, arranged in a row Signals can be read out in units of lines or several lines, and signals can be read out from any block area. Furthermore, it has a light-emitting reading mode that adjusts parameters related to the readout of the solid-state imaging device (14) when emitting light so that all rows constituting a predetermined block area of the solid-state imaging device (14) are generated. shared exposure period. Accordingly, even when flash photography is performed at a high shutter speed, high-precision light intensity detection can be performed.

Description

Image pickup device, control method of image pickup device

technical field

The present invention relates to an image pickup device and a control method of the image pickup device capable of performing light emission such as pre-light emission for photometry. More specifically, it relates to an image pickup device and a control method suitable for a solid-state imaging device using a solid-state imaging device such as a CMOS sensor, in which a plurality of photoelectric conversion elements are two-dimensionally arranged and capable of Alternatively, driving is performed with the exposure period shifted in units of several lines.

Background technique

In recent years, solid-state imaging devices integrating photoelectric conversion elements at a high density have been used in video cameras and digital cameras, etc., and are capable of recording multiple sheets of image data on a recording medium, printing out image data, or displaying it on a monitor.

Such video cameras, digital cameras, etc. employ an automatic exposure (AE: Automatic Exposure) function to measure the amount of light on an imaging surface at the time of gaze, and perform exposure under the obtained optimum exposure conditions.

In addition, there is an auxiliary light-emitting device such as a flash or an electronic flash (strobo), and when shooting at night or indoors when there is little light, the auxiliary light-emitting device is flashed to take pictures (flash photography).

It is actually difficult to use the AE function to control the exposure instantaneously when the flash is fired. Therefore, it is generally used to perform pre-lighting for metering, measure the amount of light at this time, end the automatic exposure control before the flash is fired, and then perform Formal photography. Normally, the amount of flash light cannot be accurately measured even with pre-light emission outside the accumulation time of the solid-state imaging device, so the pre-light emission is performed in synchronization with the flash emission timing to perform the accumulation operation.

In recent years, in order to achieve high resolution in video cameras, digital cameras, and the like, efforts have been made to reduce the cell size of photoelectric conversion elements using a miniaturization process.

On the other hand, since the output of the photoelectric conversion signal per unit decreases with the reduction of the unit size, etc., an amplifying solid-state imaging device capable of amplifying and outputting the photoelectric conversion signal has attracted attention. As such an amplifying solid-state imaging device, there are two-dimensional solid-state imaging devices of XY address type sensors such as BASIS, MOS type, SIT, AMI, and CMD.

In addition, as other two-dimensional solid-state imaging devices, CCD (Charge Coupled Device) sensors are widely used due to their excellent performance in terms of high density and high S/N.

In a digital camera or the like having a two-dimensional solid-state imaging device, when capturing an image, the exposure conditions for the imaging are appropriately adjusted, and an exposure time is set in accordance with the sensitivity of the solid-state imaging device. When setting this exposure time, measure the amount of light irradiated on a part of the two-dimensionally arranged photoelectric conversion elements, and change photographic parameters such as the aperture until the value of the measured light amount becomes a certain target value, and find the optimum value. . This action is AE (Automatic Exposure).

When performing AE in a digital camera using a CCD sensor, all pixel data is read out and stored in a storage medium, and a predetermined block area is extracted from it, temporarily accumulated, and compared with an appropriate predetermined exposure level. Then, the pixel data read out by changing the imaging parameters such as the shutter speed and the aperture are extracted again and compared with a predetermined exposure level. By repeating this a plurality of times, the condition when the exposure level of the block area becomes the predetermined exposure level is determined as the optimum exposure condition.

The AE operation performed by the solid-state imaging device using the CCD sensor will be described with reference to FIGS. 17A to 17C . Whether the reading mode of the sensor is an interline transmission mode or a frame transmission mode, the image signals read out from the CCD sensor 1601 in time series are all converted into digital image signals by the A/D converter 1602 and sent to the frame memory 1603. Write 1 frame amount.

When performing AE by center-weighted photometry, in particular, only the block area at the center is read out, and the image signal level of the block area is integrated by the integrator 1604 to obtain the integrated value of the entire block area. The judgment circuit 1605 compares all the integrated values of the block area with a predetermined predetermined exposure level, and if there is a difference in the comparison result, it is output to the exposure condition setting circuit 1606 . The exposure condition setting circuit 1606 changes, for example, the shutter speed from exposure conditions such as exposure time to the CCD sensor 1601 , shutter speed, aperture value, accumulation time of the CCD sensor 1601 , and the like. With the exposure conditions corresponding to the settings in the exposure condition setting circuit 1606, the exposure integral value of the block area in the image data acquired by the CCD sensor 1601 is detected again, compared and determined by the determination circuit 1605, and these operations are repeated until Optimum exposure conditions are obtained until the difference becomes equal to or less than a predetermined value.

This AE operation is shown as a timing chart in FIG. 17B. In FIG. 17B , the exposure time (charge accumulation time) is represented by a low level period in (1). In (2) at the time of AE evaluation, after charge accumulation and A/D conversion, the block area is read from the frame memory 1603, and the integration processing period is indicated at a high level. In addition, in the AE value (3) at the time of each AE evaluation, what is shown by the dotted line is a predetermined AE value. If it is represented by a graph (graph), it will become Fig. 17C. In the third exposure detection value, the AE value is too high. By using the exposure condition at the fourth AE value as the condition for AE, it is possible to execute The best AE.

In recent years, CMOS sensors have been increasingly used in two-dimensional solid-state imaging devices for reasons such as low cost, no need for complicated timing signal generators, operation with a single power supply, and low power consumption.

However, the CMOS sensor reads out signals in units of rows, so the start time of accumulating photocharges in each row is staggered. Therefore, the timing of light accumulation for AE may be shifted for each row, and the accumulation time of the block area used for AE evaluation may be shifted from the pre-emission time. That is, among the lines included in the block area used for AE evaluation, there may be lines that are not accumulated in the pre-light emission.

As a countermeasure against this problem, Japanese Patent Application Laid-Open No. 2000-196951 discloses, for example, that pre-emission is performed during a period in which each reading line in a block area overlaps in time, thereby pre-lighting. The glow is illuminated over the entire block area.

However, when the shutter speed is high such as during daytime synchronous (synchro) shooting, there may be no period in which the read lines in the block area temporally overlap. In such a case, if pre-emission is performed at any timing, the photocharges of the photographic light composed of external light and reflected light from the flash are mixed with the photocharges of photographic light composed of external light and accumulated in the CMOS. in the sensor. As a result, there is a problem that an accurate amount of light cannot be detected.

Contents of the invention

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize high-precision light quantity detection even when a high-speed shutter operation is performed when emitting light.

In order to achieve the above object, the image pickup device according to the first aspect of the present invention is characterized in that it includes: an imaging unit arranged with pixels including photoelectric conversion elements in multiple rows; The above-mentioned camera unit; and the control unit, when emitting light, can switch the reading mode of reading signals from the predetermined area of the above-mentioned camera unit to a light-emitting reading mode different from that of the through display, wherein the through display is from The continuous images sequentially output by the imaging unit are displayed on the display unit; wherein, the above-mentioned light-emitting reading mode is such that a part of the exposure period of the row first read out overlaps in time with a part of the exposure period of the row read out last .

In addition, in order to achieve the above object, an image pickup device according to another aspect of the present invention is characterized in that it includes: an imaging unit arranged with pixels including photoelectric conversion elements in multiple rows; The above-mentioned camera unit; and the control unit, when emitting light, can switch the reading mode of reading signals from the predetermined area of the above-mentioned camera unit to a light-emitting reading mode different from that of the through display, wherein the through display is from The continuous images sequentially output by the imaging unit are displayed on the display unit; wherein the light-emitting reading mode is such that the reading period for reading signals from a predetermined area of the imaging unit is shorter than the reading period of the reading mode during the above-mentioned through display. The withdrawal period is short.

Furthermore, the above objects can also be achieved by a method for controlling an image pickup device including an imaging unit arranged with pixels including photoelectric conversion elements in a plurality of rows, and driving the imaging unit by shifting the exposure periods in units of one row or several rows. The driving unit of the present invention, the control method is characterized in that it includes the step of switching the reading mode for reading signals from a predetermined area of the above-mentioned imaging unit to a light-emitting reading mode different from that of the through display when emitting light, wherein the through It is shown that successive images output sequentially from the imaging unit are displayed on the display unit, wherein the above-mentioned light-emitting reading mode is such that a part of the exposure period of the row read out first and a part of the exposure period of the row read out last are displayed on the display unit. overlap in time.

In addition, the above object can also be achieved by a method for controlling an image pickup device including an image pickup unit arranged in multiple rows of pixels including photoelectric conversion elements, and driving the above-mentioned image pickup unit by shifting exposure periods in units of one row or several rows. The driving unit of the present invention, the control method is characterized in that it includes the step of switching the reading mode for reading signals from a predetermined area of the above-mentioned imaging unit to a light-emitting reading mode different from that of the through display when emitting light, wherein the through The display is to display continuous images sequentially output from the above-mentioned imaging unit on the display unit; wherein, the above-mentioned light-emitting reading mode is such that the reading period for reading signals from a predetermined area of the above-mentioned imaging unit is shorter than the reading period of the above-mentioned through display. The read period of the fetch mode is short.

Additional features and advantages of the invention will appear from the following description of the preferred embodiments, and the accompanying drawings, which form a part hereof, illustrate various embodiments of the invention. However, these examples are not exhaustive of the various embodiments of the invention, the scope of which is defined by the appended claims.

Description of drawings

The accompanying drawings constitute a part of this specification, illustrate embodiments of the invention, and together with the description, serve to explain the principle of the invention.

FIG. 1 is a diagram showing a configuration example of an image pickup device to which the present invention is applicable.

2 is a flowchart showing a part of a main routine (routine) of processing operations of the image pickup device according to the first embodiment.

3 is a flowchart showing a part of the main routine of the processing operation of the image pickup device according to the first embodiment.

FIG. 4 is a flowchart showing ranging, photometry, and color measurement processing.

FIG. 5 is a flowchart showing imaging processing.

FIG. 6 is a flowchart showing recording processing.

FIG. 7 is a sequence diagram of processing operations when the flash is ON.

Fig. 8 is a circuit diagram of a CMOS sensor.

FIG. 9 is a diagram showing a circuit configuration of an adding circuit.

10A and 10B are diagrams for explaining the reading method of the CMOS sensor and the EF operation.

FIG. 11 is a diagram showing the timing of accumulation time of an EF evaluation block when the shutter speed is 1/60.

FIG. 12 is a diagram showing the timing of the accumulation time of the EF evaluation block when the shutter speed is 1/250.

FIG. 13 is a diagram showing the timing of accumulation time when the number of horizontal pixels to be read, the drive frequency, or the horizontal blanking time are changed.

FIG. 14 is a diagram showing the timing of accumulation time when the number of vertical pixels to be read is changed.

15 is a flowchart showing a part of the main routine of the processing operation of the image pickup device according to the second embodiment.

16 is a diagram showing the relationship between the shutter speed and the driving frequency of the image pickup device according to the third embodiment.

17A to 17C are diagrams for explaining the AE method of a solid-state imaging device using a CCD.

Detailed ways

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

(first embodiment)

FIG. 1 is a diagram showing a configuration example of an image pickup device 100 such as a digital camera to which the present invention is applicable. In this figure, 10 is a photographic lens. 12 is the shutter with aperture function. 14 is a solid-state imaging element (solid-state imaging device). In this embodiment, a CMOS sensor is used in which a plurality of pixels including photoelectric conversion elements are arranged in a matrix, and signals are read out in units of one row or several rows, and Signals can be read from any block area. 16 is an A/D converter which converts the analog signal output of the solid-state imaging element 14 into a digital signal.

18 is a timing generator circuit for supplying clock signals and control signals to the solid-state imaging device 14 , A/D converter 16 , and D/A converter 26 , and is controlled by the memory control unit 22 and the system control unit 50 .

20 is an image processing unit that performs predetermined pixel interpolation processing and color conversion processing on the image data from the A/D converter 16 or the image data from the memory control unit 22 . Furthermore, the image processing unit 20 performs predetermined arithmetic processing using the image data output from the A/D converter 16 . Then, based on the calculation result, the system control unit 50 performs TTL (Through The Lens) autofocus (AF) processing, automatic exposure (AE) processing, and flash pre-emission (EF) processing on the exposure control unit 40 and the distance measurement control unit 42 . )deal with. Furthermore, the image processing unit 20 performs predetermined calculation processing using the image data output from the A/D converter 16, and also performs TTL-based automatic white balance (AWB: Auto White Balance) processing based on the obtained calculation results.

22 is a memory control unit, which controls the A/D converter 16, the timing generation circuit 18, the image processing unit 20, the image display memory 24, the D/A converter 26, the memory 30, and the compression/decompression unit 32. The image data output from the A/D converter 16 is written into the image display memory 24 or the memory 30 via the image processing unit 20 , the memory control unit 22 , or only via the memory control unit 22 .

24 is an image display memory, 26 is a D/A converter, and 28 is an image display section composed of a TFT LCD or the like. The display image data written in the image display memory 24 is displayed on the image display unit 28 via the D/A converter 26 .

If the captured image data is sequentially displayed using the image display unit 28, an electric viewfinder (EVF: Electric View Finder) function can be realized. In addition, the image display unit 28 can turn the display on (ON) or off (OFF) according to an instruction from the system control unit 50 . When the display of the image display unit 28 is turned off (OFF), the power consumption of the image pickup device 100 can be significantly reduced. Furthermore, the image display unit 28 displays information on in-focus, hand shake, flash charging, shutter speed, aperture value, exposure correction, and the like in accordance with instructions from the system control unit 50 .

30 is a memory for storing captured still images and moving images, and has a sufficient storage capacity to store a predetermined number of still images and moving images for a predetermined time. Thereby, even in the case of continuous shooting or panorama shooting in which a plurality of still images are continuously captured, a large number of images can be written into the memory 30 at high speed. Furthermore, the memory 30 can also be used as a work area of the system control unit 50 .

32 is a compression/decompression unit for compressing and decompressing image data by Adaptive Discrete Cosine Transform (ADCT) or the like. It has the function of compressing the image data read from the memory 30 and writing the compressed image data into the memory 30, decompressing the image data read from the memory 30, and writing the decompressed image A function of writing data into the memory 30 .

Reference numeral 40 denotes an exposure control unit for controlling the shutter 12 having a diaphragm function, and cooperates with a flash 48 to also have a flash dimming function. 42 is a ranging control unit for controlling the focusing of the taking lens 10, 44 is a zoom control unit for controlling the zooming of the taking lens 10, and 46 is a lens cap control unit for controlling the operation of the lens cap 102 for protecting the lens. 48 is a flash, which has the projection function of the AF auxiliary light and also has the dimming function of the flash. The exposure control unit 40 and the distance measurement control unit 42 are controlled using the TTL method. As described above, the control unit 50 controls the exposure based on the calculation result obtained by the image processing unit 20 on the image data from the A/D converter. The control unit 40 and the ranging control unit 42 .

50 is a system control unit that controls the entire image pickup device 100 , and 52 is a memory that stores constants, variables, programs, etc. for the operation of the system control unit 50 .

54 is a notification unit such as a liquid crystal display device or a speaker, which is installed at one or more easily recognizable positions near the operation unit of the image pickup device 100. The notification unit is executed according to the program of the system control unit 50 and uses characters, Images, sounds, etc. inform the operation status, messages, etc. For example, it is composed of a combination of LCDs, LEDs, sound emitting elements, and the like. Furthermore, a part of the function of the notification unit 54 is provided in the optical viewfinder 104 .

Among the display contents of the display unit 54, as the display contents displayed on the LCD or the like, there are single-shot/continuous-shooting display, self-timer display, compression rate display, recording pixel count display, recording number display, and remaining number of available shots display. , shutter speed display, aperture value display, exposure correction display, flash light display, red-eye reduction display, macro photography display, buzzer setting display, battery remaining display for clock, battery remaining display, error display, multi-digit based Digital information display, loading/removing state display of the recording media 200 and 210, communication I/F operation display, date and time display, and the like.

In addition, among the display contents of the display unit 54 , the display contents displayed in the optical viewfinder 104 include an in-focus display, a hand shake warning display, a flash charge display, a shutter speed display, an aperture value display, and an exposure correction display.

56 is an electrically erasable and recordable nonvolatile memory, for example, EEPROM etc. are used.

60, 62, 64, and 70 are operation devices for inputting various operation instructions of the system control unit 50, and are composed of one or more of a switch, a dial, a touch panel, a pointing based on line-of-sight detection, and a voice recognition device. Composition of a combination.

60 is a mode dial switch, which can switch and set various functional modes such as power OFF, automatic shooting mode, shooting mode, panoramic shooting mode, playback mode, multi-screen playback clear mode, and PC connection mode.

62 is a shutter switch SW1, which is turned ON during the operation (half-press) of the shutter button (not shown), and instructs the start of operations such as AF processing, AE processing, AWB processing, and EF processing.

64 is a shutter switch SW2, which turns ON when the operation of the shutter button (not shown) is completed (full press). By turning ON of SW2, indicating

Exposure processing of writing the signal read from the solid-state imaging element 14 into the memory 30 as image data via the A/D converter 16 and the memory control unit 22;

- Development processing using calculations of the image processing unit 20 and the memory control unit 22;

The image data is read out from the memory 30, and the compression/decompression part 32 performs image compression compression coding processing;

- A series of operations of recording processing of writing image data into the recording medium 200 or 210 starts.

Reference numeral 70 is an operation unit composed of various buttons and a touch panel. The operation part 70 includes, for example, the following buttons, keys, etc.: menu button, setting (set) button, macro/non-macro switching button, multi-screen playback page change button, flash setting button, single shooting/continuous shooting/self-timer Switch button, menu shift + (plus) button, menu shift - (minus) button, reproduced image shift + (plus) button, reproduced image shift - (minus) button, shooting quality selection button, exposure correction button, date/time setting button etc.

80 denotes a power supply control unit, which is composed of a switching battery detection circuit, a DC-DC converter, a switching circuit for switching a block to be energized, and the like. Moreover, the presence or absence of a battery, the type of the battery, and the remaining battery level are detected, and the DC-DC converter is controlled according to the detection result and the instruction of the system control unit 50, and the required voltage is provided to the recording medium at the required time. within each department.

82 and 84 are connectors, and 86 is a power supply including primary batteries such as alkaline batteries and lithium batteries, secondary batteries such as NiCd batteries, NiMH batteries, and Li batteries, and AC adapters.

90 and 94 are interfaces with recording media such as memory cards and hard disks, and 92 and 96 are connectors for connecting to recording media such as memory cards and hard disks. 98 is a recording medium insertion/removal detection part which detects whether the recording medium 200,210 is connected to the connector 92,96.

102 is a lens cover, by covering the imaging part of the image pickup device 100 including the lens 10, the imaging part is prevented from being polluted and damaged.

104 is an optical viewfinder, and it is possible to take pictures using only the optical viewfinder 104 without using the electronic viewfinder function of the image display unit 28 . Further, in the optical viewfinder 104, some functions of the display unit 54, such as in-focus display, hand shake warning display, flash charge display, shutter speed display, aperture value display, exposure correction display, etc., are provided.

110 is a communication unit, which includes various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication. 112 is a connector for connecting the image pickup device 100 to another device through the communication unit 110, or an antenna in the case of wireless communication.

Reference numerals 200 and 210 denote recording media such as memory cards and hard disks. The recording media 200 and 210 include: recording units 202 and 212 composed of semiconductor memories, magnetic disks, etc.; interfaces 204 and 214 with the image pickup device 100 ;

2 and 3 are flowcharts showing a main routine of processing operations in the image pickup device 100 . When power is turned on for battery replacement, etc., the system control unit 50 initializes flags, control variables, etc. (step S101), and initially sets the image display of the image display unit 28 to an OFF state (step S102).

The system control unit 50 determines the setting position of the mode dial switch 60 . If the mode dial switch 60 is set to power OFF (step S103), predetermined end processing is performed (step S105). The end processing includes, for example, the following processing:

・Change the display of each display unit to the end state.

Close the lens cover 102 to protect the camera unit

Record required parameters, set values, and set modes including flags, control variables, etc. into the non-volatile memory 56

Cut off the unnecessary power supply of each part of the image pickup device 100 including the image display unit 28 by the power control unit 80

After finishing the end processing, return to step S103.

On the other hand, if the mode dial switch 60 is set to the photography mode (step S103), the process proceeds to step S106. If the mode dial switch 60 is set to another mode (step S103), the system control unit 50 executes processing corresponding to the selected mode (step S104), and returns to step S103 when the processing is completed.

In the photographing mode, the system control unit 50 judges whether the remaining capacity and the operation status of the power supply 86 constituted by a battery or the like cause problems to the operation of the image pickup device 100 through the power supply control unit 80 (step S106 ). Then, if there is a problem, a predetermined warning display is performed with an image or sound using the notification unit 54 (step S108), and then returns to step S103.

If there is no problem with the power supply 86, the system control unit 50 judges whether the operation state of the recording medium 200 or 210 has a problem with the operation of the image pickup device 100, especially the recording and reproducing operation of image data performed on the recording medium 200 or 210. (step S107). Then, if there is a problem, a predetermined warning display is performed with an image or sound using the notification unit 54 (step S108), and then returns to step S103.

If there is no problem with the operating state of the recording medium 200 or 210 (step S107), the notification unit 54 is used to notify the user of various setting states of the image pickup device 100 through images and sounds (step S109). In addition, when the image display of the image display unit 28 is ON, the image display unit 28 may be used to notify the user of various setting states of the image pickup device 100 through images and sounds.

Next, the system control unit 50 sets to a through display state in which the captured image data is sequentially displayed (step S116 ). The through display state is a state for causing the image display unit 28 to function as an electronic viewfinder. Specifically, the data sequentially written in the image display memory 24 via the solid-state imaging element 14, the A/D converter 16, the image processing unit 20, and the memory control unit 22 is transferred to the image display memory 24 via the memory control unit 22, the D/A converter 26, displayed sequentially by the image display unit 28.

Next, the state of the shutter switch SW1 is checked, and if the shutter switch SW1 is OFF (step S119), the process returns to step S103. If the shutter switch SW1 is ON (step S119), the system control unit 50 performs distance measurement processing, focuses the photographic lens 10 on the subject, performs photometry processing, and determines the aperture value and shutter speed. In the light metering process, a flashlight flag is also set (set) if necessary, and the flashlight is set (step S120). Details of the ranging, photometry, and colorimetry processing will be described later using FIG. 4 .

If the distance measuring, light measuring and color measuring processing is completed (step S120), the state of the shutter switch SW2 is checked. If the shutter switch SW2 is not pressed (step S121), and the switch SW1 is also released (step S122), the process returns to step S103. If the shutter switch SW2 is not pressed (step S121) and the switch SW1 remains ON (step S122), then return to step S121.

If the shutter switch SW2 has been pressed (step S121), the system control unit 50 determines whether or not a flash is required based on whether there is a flash flag set in the distance measurement, photometry, and color measurement processing (step S120) as described later. (step S127). If a flash is required, the signal reading mode for reading out signals from the solid-state imaging device 14 is switched from the previous EVF reading mode to the pre-emission reading mode (step S128), and pre-emission/exposure processing (step S128) is performed (step S128 ). S129). If no flashlight is needed, go to step S123. The details of the pre-luminescent reading mode will be discussed later.

Next, the system control unit 50 performs exposure processing via the solid-state imaging device 14, the A/D converter 16, the image processing unit 20, and the memory control unit 22, or directly from the A/D converter 16 via the memory control unit 22, The captured image data is written into the memory 30 . Then, imaging processing consisting of developing processing for reading out the image data written in the memory 30 and performing various processes using the memory control unit 22 and, if necessary, the image processing unit 20 (step S123). Details of this imaging processing will be described later using FIG. 5 .

After the imaging process is completed, the system control unit 50 reads the captured image data written in the memory 30, and performs various image processing using the memory control unit 22 and, if necessary, the image processing unit 20. In addition, image compression processing according to the set mode is performed using the compression/decompression unit 32, and then recording processing of writing image data to the recording medium 200 or 210 is performed (step S124). Details of this recording process will be described later using FIG. 6 .

After the recording process ends, check the state of the shutter switch SW2 (step S125), if it is OFF, then return to step S103, if it is ON, then confirm whether it is set to continuous shooting mode (step S126). If the continuous shooting mode is not set, return to step S125, wait for the release of the shutter switch SW2, and return to step S103. If it is set to the continuous shooting mode, return to step S123 for the next shooting.

FIG. 4 is a flowchart showing details of the ranging, photometry, and colorimetry processing in step S120 of FIG. 3 . The system control unit 50 reads the charge signal from the solid-state imaging device 14, and sequentially reads image data into the image processing unit 20 via the A/D converter 16 (step S201). The image processing unit 20 performs predetermined calculations for AE processing, EF processing, and AF processing of the TTL method using the image data read in this order. In addition, the various processes here are to cut and extract the required specific part of the total number of pixels that meet the needs, and use it for calculation. In this way, in each processing of AE, EF, AWB, and AF of the TTL method, it is possible to perform optimum calculations for each of various modes such as the center-weighted mode, the average mode, and the evaluation mode.

The system control unit 50 performs AE control using the exposure control unit 40 (step S203 ) until it is determined that the exposure (AE) is appropriate using the calculation result of the image processing unit 20 (step S202 ). The system control unit 50 uses the measurement data obtained through AE control to determine whether a flash is needed (step S204), and if necessary, sets the flash flag to charge the flash 48 (step S205). If no flashlight is needed, then return to step S201.

If it is determined that the exposure (AE) is appropriate (step S202 ), the measurement data and/or setting parameters are stored in the internal memory of the system control unit 50 or the memory 52 .

Next, the system control unit 50 performs automatic white balance (AWB) control processing using the calculation result of the image processing unit 20 and the measurement data obtained by the AE control. That is, the parameters of the color processing are adjusted using the image processing unit 20 (step S207) until it is determined that the white balance is appropriate (step S206). If it is determined that the white balance is appropriate (step S206 ), the measurement data and/or setting parameters are stored in the internal memory of the system control unit 50 or the memory 52 .

AF control is performed in the system control unit 50 using the ranging control unit 42 (step S209) until the ranging (AF) is determined to be in-focus using the measurement data obtained in the AE control and AWB control (step S208). If it is determined that the distance measurement (AF) is in-focus (step S208), the measurement data and/or setting parameters are stored in the internal memory of the system control part 50 or in the memory 52, and the distance measurement, light measurement and color measurement are completed. handler.

FIG. 5 is a detailed flowchart showing the imaging processing in step S123 in FIG. 3 .

As described in FIG. 4 , the system control unit 50 controls the exposure control unit 40 according to the photometry data stored in the internal memory of the system control unit 50 or the memory 52, so that the shutter 12 having the aperture function is opened according to the aperture value ( Step S301). Then, exposure of the solid-state imaging device 14 is started (step S302).

Next, it is determined whether a flashlight is needed according to the flashlight sign (step S303), and if necessary, the flashlight 48 is turned on (step S304). If the strobe is unnecessary, the process proceeds to step S306 without lighting the strobe 48 .

The system control unit 50 waits for the end of the exposure of the solid-state imaging device 14 according to the photometric data (step S305 ). After the exposure time is over, the shutter 12 is closed (step S306 ), and the charge signal is read out from the solid-state imaging device 14 . Then, the image data is written into the memory 30 via the A/D converter 16, the image processing unit 20, the memory control unit 22, or directly from the A/D converter 16 via the memory control unit 22 (step S307).

Next, according to the set photographing mode, after color finishing processing is performed sequentially (step S310 ), the processed image data is written into the memory 30 , and the photographing processing procedure ends.

FIG. 6 is a detailed flowchart showing the recording process in step S124 of FIG. 3 . The system control unit 50 uses the memory control unit 22 and, if necessary, the image processing unit 20 to read the image data written in the memory 30, and the compression/decompression unit 32 performs image compression processing according to the set mode. (step S402). Then, the compressed image data is written into the recording medium 200 or 201 such as a memory card or a CF (compactflash: registered trademark) card via the interface 90 or 94 and the connector 92 or 96 (step S403), and the recording processing procedure ends.

In the image pickup device described above, when the flash is ON, as also shown in FIG. Step S120). Thereafter, when the shutter switch SW2 is turned ON (step S121), the signal reading method for reading signals from the solid-state imaging device 14 is switched from the EVF reading mode to the pre-emission reading mode (step S128). Then, as pre-light emission and exposure processing, pre-light emission, pre-exposure, and signal reading are performed (step S129). That is, at the time of pre-emission, it shifts to the pre-emission reading mode which is different from the EVF reading mode and the main exposure reading mode. In this way, by performing the pre-firing/exposure processing immediately after the shutter switch SW2 is turned ON, the time between the main exposure start time and the pre-exposure start time can be shortened, so that high-precision flash light control can be realized.

In this case, when the shutter switch SW2 is turned ON, the update of the display (EVF output) of the image display device 28 is suspended, and the signal read in the pre-emission reading mode is not displayed through through.

FIG. 8 is a circuit diagram of a CMOS sensor used as the solid-state imaging element 14 .

In the figure, B11 to B44 are pixels including photoelectric conversion elements such as photodiodes, amplification MOS transistors for reading and amplifying accumulated charges in the photoelectric conversion elements, selection MOS transistors for activating the amplification MOS transistors, and the like. The pixels are arranged in a matrix (4×4 pixels in the illustrated example).

In the EVF reading mode, for example, it is set to add and average 2 pixels in the horizontal direction and 2 pixels in the vertical direction. That is, the VSEL1 read out from the vertical shift memory 801 for each horizontal row is output, and the light output of each pixel selected by the control pulse of VSEL1 is read out to the vertical output lines VSIG1 to 4 and stored in the addition circuit 802. .

FIG. 9 is a diagram showing the circuit configuration of the adding circuit 802, and shows a case where light outputs of two pixels B11, B12 in the horizontal direction and two pixels B12, B22 in the vertical direction are added. As shown in the figure, signal components of pixels B11 and B12 are stored in storage capacitors 903 and 904 via transfer switches 901 and 902 from vertical output lines connected to the respective pixels. VSEL2 in FIG. 8 is output at the next timing, and signal components of pixels B21 and B22 are stored in storage capacitors 907 and 908 via transfer switches 905 and 906 .

Then, according to a control signal from the horizontal shift register 803, the transfer switches 909, 910, 911, 912 are turned ON. Thus, in the horizontal output line 913, the signal components of the pixels B11 and B12 in the horizontal direction and the signal components of the pixels B21 and B22 in the vertical direction are added, and the addition of horizontal and vertical pixels is completed.

Here, the timing shift when a rolling electronic shutter method such as a CMOS sensor is used will be described with reference to the reading method of the CMOS sensor in FIG. 10A and the explanatory diagram of the pre-emission (EF) in FIG. 10B . . FIG. 10A shows, for example, the accumulation timing of photocharges in the pre-emission evaluation block region based on the EF of a CMOS sensor. When accumulating photocharges received by CMOS, the signal is read out in units of one row, so the accumulation starts of each row n, n+1, n+2,..., m are staggered respectively.

Furthermore, for the EF operation, the light intensity when pre-lighting the flash within a certain period of time changes as shown in FIG. Part of the block area is evaluated. At this time, all the rows n to m of the EF evaluation block area must accumulate charges in the pre-emission period.

That is, if not all the EF evaluation block regions receive the pre-emission light, the flicker cannot be accurately detected, resulting in a decrease in accuracy. In the example of FIG. 10A and FIG. 10B , all the EF evaluation block regions receive the pre-emission light.

Next, a case where the pre-light emission cannot be projected onto a part of the EF evaluation block area will be described with an example.

[Normal flash photography (shutter speed 1/60sec)]

FIG. 11 shows the timing of the accumulation time of the EF evaluation block area. Currently, the shutter speed is 1/60sec, so the accumulation time becomes 16.7ms. Furthermore, assuming that the time required to read one line is 24 μs and the number of lines in the vertical direction of the EVF is 180, the reading time per one screen is 24 μs×180=4.3 ms. As can be seen from FIG. 11 , the overlapping period of accumulation time of all rows in the EF block area is 12.4 ms. Assuming that the pre-light emission time is 20 μs, by performing the pre-light emission during this overlapping period, it is possible to project the pre-light emission to all the rows in the EF evaluation block area.

〔During daytime synchronization shooting (shutter speed 1/250sec)〕

FIG. 12 shows the timing of the accumulation time of the EF evaluation block area. Currently, the shutter speed is 1/250sec, so the accumulation time becomes 4ms. Furthermore, it is assumed that the time required to read one line and the number of lines in the vertical direction are the same as those in normal flash photography. In this case, it can be seen from FIG. 12 that there is no temporal overlap period in all the rows in the EF evaluation block area, so no matter what timing the pre-light emission is performed, the pre-light emission cannot be projected to the EF evaluation block area. Part of the line.

In this way, when the shutter speed is high, such as during daytime synchronous photography, the accumulation time becomes shorter than the time required to read out one line. Therefore, among the rows of the EF evaluation block area, rows that are not pre-illuminated appear.

According to the above results, when the synchronous shutter speed, the readout time of the signal readout from the EF evaluation block area, and the pre-light emission time satisfy the following formula (1), the pre-light emission can be projected to all the EF evaluation block areas.

Synchronous shutter speed ≥ reading time + pre-lighting time ... Formula (1)

Therefore, by changing the parameters for shortening the reading period of signals from a predetermined area (4×4 pixels in this embodiment) of the solid-state imaging element as described below at the time of pre-emission, it is read by pre-emission mode to act.

(1) Read the number of horizontal pixels

(2) Drive frequency

(3) Horizontal blanking time

(4) Read the number of vertical pixels

By changing the values of (1), (2), and (3), the inclination of the parallelogram in the timing chart can be changed. This situation is shown in FIG. 13 . Furthermore, when the value of (4) is changed, the number of read lines changes, so the timing chart changes as shown in FIG. 14 . By changing at least one of these four values, it is possible to temporally overlap the first read line and the last read line within the accumulation time determined by the shutter speed. Therefore, a pre-emission reading mode in which the pre-emission is projected on all the EF evaluation block regions can be used.

(second embodiment)

In the first embodiment described above, the pre-light emission reading mode is always shifted to during the pre-light emission. Furthermore, in the pre-light reading mode, as described above, by setting (1) the number of horizontal pixels to be read, (2) the drive frequency, (3) the horizontal blanking time, and (4) the number of vertical pixels to be read as appropriate value, causes the pre-illumination to be projected to all EF evaluation block areas.

However, in order to cope with the high-speed shutter, the number of read horizontal pixels and the number of read vertical pixels tend to be reduced. If the interval is too large, the dimming accuracy of the flash may decrease. Moreover, the driving frequency tends to increase, so it is also considered that the power consumption may also increase accordingly. Moreover, the horizontal blanking time tends to decrease, so it is considered that the sensor performance may deteriorate due to the high-speed switching speed.

In the present embodiment, it is judged whether or not the pre-light emission can be projected to all EF evaluation block regions, and only when the judgment is negative, it shifts to the pre-light emission reading mode. FIG. 15 is a flow chart corresponding to FIG. 3 in the first embodiment, and the same reference numerals are assigned to the same processing operations as those in FIG. 3 , and only the differences will be described here.

When the shutter switch SW2 is pressed (step S121), the system control unit 50 determines whether or not a flash is necessary (step S127). If necessary, it is first judged whether the shutter speed is greater than or equal to a threshold (step S130). This threshold is equal to "reading time + pre-light emission time" shown in the above formula (1). Then, if the shutter speed is not greater than or equal to the threshold value, the pre-light cannot be projected to all EF evaluation block areas, so it switches to the pre-light reading mode (step S128). However, if the shutter speed is equal to or greater than the threshold value, the EVF reading mode is maintained (step S131), and pre-emission/exposure processing is performed accordingly (step S129).

(third embodiment)

In the first embodiment, (1) the number of horizontal pixels to be read, (2) the driving frequency, (3) the horizontal blanking time, and (4) the number of vertical pixels to be read are adjusted in the pre-emission mode so that even at high speed The shutter also enables pre-lighting to be projected to all EF evaluation block areas.

However, since the driving frequency is adjusted so that it tends to increase, it is considered that the power consumption may increase.

In this embodiment, the drive frequency is changed according to the shutter speed. Currently, three types of sensors, 40MHz, 20MHz, and 10MHz, can be selected for the driving frequency.

In addition, the synchronous shutter speed of the digital camera is set to 1/500s (2ms), and the pre-lighting time is set to 1/2000s (0.5ms), and the reading time at 40MHz drive is 1.5ms. In this case, the synchronized shutter speed becomes equal to or greater than (reading time at 40 MHz driving + pre-light emission time), and the pre-light emission is projected to all EF evaluation block areas.

Furthermore, it is assumed that the reading time when driving at 20 MHz is 2 ms, and the reading time when driving at 10 MHz is 2.5 ms. In this case, when driving at 20 MHz, the minimum shutter speed satisfying the above formula (1) is read time 2 ms + pre-emission time 0.5 ms = 2.5 ms (1/400 s). That is, it is also possible to set the drive frequency to 20 MHz at a shutter speed of 2.5 ms or more. Similarly, when driving at 10 MHz, the minimum shutter speed satisfying the above formula (1) is read time 2.5 ms + pre-emission time 0.5 ms = 3.0 ms (1/333 s). That is, it is also possible to set the drive frequency to 10 MHz at a shutter speed of 3.0 ms or more.

That is, the shutter speed Tv and the drive frequency are summarized as follows.

(Case 1) 2ms≤Tv<2.5ms and the driving frequency of 40MHz satisfy the above formula (1).

(Case 2) 2.5ms≦Tv<3ms and the driving frequency of 20MHz satisfy the above formula (1).

(Case 3) 3ms≦Tv satisfies the above formula (1) at a drive frequency of 10MHz.

The above relationship is summarized in FIG. 16 . Based on this, it is not necessary to drive at a frequency of 40MHz all the time, but the driving frequency can be slowed down according to the shutter speed, and as a result, power consumption can be reduced.

(Other implementations)

In addition, it is obvious that the purpose of the present invention can also be achieved in this way: the storage medium recording the program code of the software for realizing the functions of the above-mentioned embodiments is provided to a system or device, and the computer (or CPU, MPU) of the system or device reads output and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage code itself and the storage medium storing the program code constitute the present invention.

As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

Moreover, the functions of the above-described embodiments can be realized not only by executing the program code read out by the computer, but the OS (basic system or operating system) or the like running on the computer performs part or all of the actual processing according to the instruction of the program code, and through It is obvious that the case where the processing realizes the functions of the above-described embodiments is also included in the scope of the present invention.

Furthermore, after the program code read from the storage medium is written into the memory of the function expansion card inserted in the computer or the function expansion unit connected to the computer, according to the instruction of the program code, the function expansion Of course, it is also within the scope of the present invention that the CPU included in the card or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized through this processing.

Above, the present invention has been described in detail through the preferred embodiments. On the premise of not departing from the spirit and scope of the present invention, various changes can be made to the present invention, and it should be understood that the present invention is not limited by the above specific embodiments. manner, the scope of which is defined by the appended claims.

Claims (11)

1. An image capture device, characterized in that, comprising: a camera unit configured with multiple rows of pixels including photoelectric conversion elements; a driving unit, which drives the above-mentioned imaging unit by shifting the exposure periods in units of one or several rows; and The control unit, when emitting light, can switch the reading mode of reading signals from the predetermined area of the above-mentioned imaging unit to a light-emitting reading mode different from that of the through-display, wherein the through-display is sequentially output from the above-mentioned imaging unit Continuous images of are displayed on the display unit; Here, in the luminescence reading mode described above, a part of the exposure period of the row read first and a part of the exposure period of the row read last are temporally overlapped. 2. An image capture device, characterized in that, comprising: a camera unit configured with multiple rows of pixels including photoelectric conversion elements; a driving unit, which drives the above-mentioned imaging unit by shifting the exposure periods in units of one or several rows; and The control unit, when emitting light, can switch the reading mode of reading signals from the predetermined area of the above-mentioned imaging unit to a light-emitting reading mode different from that of the through-display, wherein the through-display is sequentially output from the above-mentioned imaging unit Continuous images of are displayed on the display unit; In the light emission reading mode, a reading period for reading out a signal from a predetermined area of the imaging unit is shorter than that of the reading mode for the through display. 3. The image capture device according to claim 1 or claim 2, characterized in that: In the light emission reading mode, the condition that the shutter speed is greater than or equal to the sum of the reading time for reading a signal from a predetermined area of the imaging unit and the light emission time is satisfied. 4. The image capture device according to claim 1 or claim 2, characterized in that: Change the value of any one or more of the read horizontal pixel count, drive frequency, horizontal blanking time, and read vertical pixel count. 5. The image capture device according to claim 4, characterized in that: When changing the value of the driving frequency, the driving frequency is changed according to the shutter speed. 6. The image capture device according to claim 1 or claim 2, characterized in that: Through display is not performed in the above-mentioned luminescent reading mode. 7. The image capture device according to claim 1 or claim 2, characterized in that: It has a first shutter switch for instructing the start of automatic exposure processing and a second shutter switch for instructing the start of photography. When the flash is on, when the second shutter switch is on, the light emission reading mode is switched to. 8. The image capture device according to claim 1 or claim 2, characterized in that: During the light emission, the shutter speed is compared with a predetermined threshold value, and the light emission reading mode is switched to the light emission reading mode based on the comparison result. 9. The image capture device according to claim 8, characterized in that: The above-mentioned predetermined threshold is the sum of the reading time and the light-emitting time for reading out the signal from the predetermined area of the above-mentioned imaging unit. 10. A control method for an image pickup device, the image pickup device comprising an imaging unit arranged with pixels including photoelectric conversion elements in a plurality of rows, and a drive unit for driving the imaging unit by shifting exposure periods in units of one row or several rows, the The control method is characterized by: It includes the step of switching the reading mode for reading out signals from a predetermined area of the imaging unit to a lighting reading mode different from that of the through display when emitting light, wherein the through display is a continuous signal to be sequentially output from the imaging unit. The image is displayed on the display unit, Here, in the luminescence reading mode described above, a part of the exposure period of the row read first and a part of the exposure period of the row read last are temporally overlapped. 11. A control method for an image pickup device, the image pickup device comprising an imaging unit arranged with pixels including photoelectric conversion elements in multiple rows, and a drive unit for driving the imaging unit by shifting exposure periods in units of one row or several rows, the The control method is characterized by: It includes the step of switching the reading mode for reading out signals from a predetermined area of the imaging unit to a lighting reading mode different from that of the through display when emitting light, wherein the through display is a continuous signal to be sequentially output from the imaging unit. The image is displayed on the display unit, In the light emission reading mode, a reading period for reading out a signal from a predetermined area of the imaging unit is shorter than that of the reading mode for the through display.

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