JP2000125205A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital camera where a time required for correction arithmetic operation of a dark output can be reduced in a waiting time during photographing. SOLUTION: In the digital camera with a CCD 11 that converts an object image into an electric signal, an aperture 2 is used to conduct exposure to the CCD 11 and image data are obtained from the CCD 11. Furthermore, a focal plane shutter 10 controls transmission or shutting of an object light to the CCD 11 and the image data obtained from the CCD 11 are stored on a recording medium 33 by a CPU 15 and an image data controller 25. The light is shut by the focal plane shutter 10 interlocking with the exposure by the aperture 2 and dark output data are measured from the output of the CCD 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera that uses an image sensor and captures a subject image from the image sensor. It is related to the removed digital camera.

[0002]

2. Description of the Related Art In an image pickup device such as a CCD which has been conventionally used in an electronic image pickup apparatus, a current may be generated even when no light is received. Is what is called dark current.

[0003] The dark current is caused by the generation of electron-hole pairs due to thermal excitation of the semiconductor. The generation factor is also caused by any defect. Appeared, which limited device sensitivity and dynamic range.

[0004] The dark current has a property that the influence increases as the accumulation time of the optical signal charge becomes longer, and also has a property that the temperature dependency is large. Regarding the latter temperature dependency, for example, when the temperature rises by about 8 to 10 ° C., the value generally becomes about twice.

As means for reducing the influence of such a dark current, an optical black portion (optical black) serving as an optically shielded portion is provided in a part of the image pickup device, and a sensor output is obtained from a normal exposure portion. At the same time, the output is also obtained from this optical black part, and these outputs are compared, etc., and the black level is fixed to the light-shielded output reference (clamp).
Is used.

[0006]

However, according to the above-mentioned method, it is necessary to perform correction including temperature characteristics on pixels in an exposed portion having substantially the same dark current characteristics as those of light-shielded pixels. However, correction cannot be performed for fixed pattern noise or fluctuation in temperature characteristics of dark current for each pixel.

For example, Japanese Patent Application Laid-Open No. Hei 8-51571 discloses that after integrating an image pickup device for photographing to obtain image data, the image pickup device is shaded and integrated to obtain dark output correction data. A technique is disclosed in which a correction operation is performed from image data and dark output correction data to correct dark output.

However, the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-517
In the technique disclosed in Japanese Patent Application Laid-Open No. H11-264, it is necessary to measure a dark output after photographing and to perform a dark output correction operation, which requires time. Therefore, the waiting time until the next photographing becomes longer, and there is a possibility that a shutter chance is missed.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a digital camera capable of shortening the time required for performing a dark output correction calculation during a waiting time during photographing.

[0010]

That is, the present invention relates to a digital camera having an electronic image pickup device for converting a subject image into an electric signal. Exposure means for obtaining the image data, light-blocking means for controlling transmission or blocking of subject light to the image sensor, and recording means for recording image data obtained from the image sensor. In conjunction with the operation, light is shielded by the light shielding means, dark output data is measured from the output of the image sensor, and both image data and dark output data are recorded in the recording means.

According to another aspect of the present invention, there is provided a digital camera having an electronic image pickup device for converting a subject image into an electric signal, wherein the exposure device exposes the image pickup device and obtains image data from the image pickup device. Light-shielding means for controlling transmission or shading of subject light to the image sensor; dark output measurement means for measuring dark output data from an output of the image sensor in a state where light is shielded by the light-shielding means; Recording means for recording the image data obtained from the above, a first shooting mode in which only the exposure operation of the exposure means is performed, and both the measurement of the dark output correction data by the dark output measurement means and the exposure operation of the exposure means. Mode switching means for switching between the second shooting mode to be performed.

According to the present invention, in a digital camera having an electronic image pickup device for converting a subject image into an electric signal, exposure is performed on the image pickup device by exposure means to obtain image data from the image pickup device. Can be Further, transmission or blocking of subject light to the image sensor is controlled by the light shielding unit, and image data obtained from the image sensor is recorded by the recording unit. Then, in conjunction with the exposure operation of the exposure unit, the light is shielded by the light shielding unit, and dark output data is measured from the output of the image sensor.

According to another aspect of the present invention, in a digital camera having an electronic image pickup device for converting a subject image into an electric signal, the image pickup device is exposed by exposure means, and image data is output from the image pickup device. can get. Further, transmission or blocking of subject light to the image pickup device is controlled by a blocking unit. In a state where the light is shielded by the light shielding means, dark output data is measured from the output of the image sensor by the dark output measuring means. Further, the image data obtained from the image sensor is recorded in a recording unit. And
A mode switching unit includes a first shooting mode in which only the exposure operation of the exposure unit is performed and a second shooting mode in which both the measurement of the dark output correction data by the dark output measurement unit and the exposure operation of the exposure unit are performed. Is switched by

According to the present invention, when performing a different dark output correction for each pixel of the image sensor, dark output correction data is obtained inside the camera, recorded on an image recording medium, and processed by an arithmetic unit external to the camera. A correction operation is performed from the image data and the dark output correction data recorded on the recording medium. Therefore, it is possible to reduce the time required for the dark output correction calculation during the waiting time between photographing.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a first embodiment of the present invention, and is a block diagram of a digital camera.

In FIG. 1, a quick return mirror that allows a photographing light beam from a subject image (not shown) to rotate in the direction of the arrow shown in FIG. 1 via a photographing lens 1 and a diaphragm 2 that is an exposure means for adjusting the amount of light. It is led to 3. The central part of the quick return mirror 3 is a half mirror,
When the quick return mirror 3 is down, a part of the light beam is transmitted. Then, the transmitted light flux is reflected by the sub mirror 4 installed on the quick return mirror 3 and
It is led to the F sensor 5.

On the other hand, the photographing light beam reflected by the quick return mirror 3 reaches the photographer's eyes via the pentaprism 6 and the eyepiece 7. Further, when the quick return mirror 3 is raised, the light beam from the photographing lens 1 reaches the CCD 11 as an imaging unit via the optical filter 9 and the focal plane shutter 10. The optical filter 9 is provided to prevent moire generated on the CCD 11, and is configured by bonding an optical low-pass filter and an infrared cut filter. The focal plane shutter 10 includes a front curtain and a rear curtain, and is a light blocking unit that controls transmission and blocking of a light beam from the photographing lens 1.

When the quick return mirror 3 is raised, the sub mirror 4 is folded. The CPU 15 has a function as a system controller. The CPU 15 includes a lens driving mechanism 16 for moving the photographing lens 1 in the optical axis direction to perform focusing.
An aperture driving mechanism 17 for driving the aperture 2; a mirror driving circuit 18 for driving the quick return mirror 3 up and down; and a shutter charging mechanism 19
A shutter control circuit 20 for controlling the traveling of the front curtain and the rear curtain of the focal plane shutter 9;
Are connected to a temperature sensor 21 installed near the eyepiece 7 and a photometric sensor 22 installed near the eyepiece 7.

The front curtain and the rear curtain of the focal plane shutter 9 have a driving source constituted by a spring, and after the shutter travels, a spring charge is required for the next operation. The shutter charging mechanism 19 is provided for the spring charging.

An image data controller 25 is connected to the CPU 15. The image data controller 25 includes an amplifier (AMP) 26 for performing voltage amplification on an analog signal corresponding to each pixel output from the CCD 11 and a timing pulse generated by a timing pulse generation circuit 27 together with the CCD 11. A / D conversion circuit 28 for A / D converting the output signal from amplifier 26, image memory 29 for temporarily storing the obtained image data, and image monitor driver 30 And the image recording circuit 32 are connected.

The image data controller 25 has the C
The drive of the CCD 11 is controlled via the timing pulse generation circuit 27 based on a command from the PU 15. Also, CCD
After performing an appropriate process on the analog signal from the image monitor 11, the image monitor 31
Or an image data recording medium 33 as recording means loaded in the camera via the image recording circuit 32.
To record.

The amplifier 26 amplifies the voltage of an analog signal output from the CCD 11 and corresponding to each pixel. The amplifier 26 is connected to the CPU 15
The amplification factor can be changed in two stages by the gain control signal from. The reason for making the gain variable will be described later.

Further, the CPU 15 has an operation display section 35 for displaying a photographing mode and the like of the camera, and a power switch of the camera for turning on / off the power according to a switch state inputted to an I / O port of the CPU 15. , A first release switch (1R SW) 37 that is turned on by a first stroke of a release button (not shown), and a second release switch that is turned on by a second stroke of a release button (not shown). (2R SW) 38 and a shooting mode for improving image quality by performing dark output correction
A high quality mode switch (HQM SW) 39 for setting an HQ (high quality) mode is connected.

Here, the reason for making the amplification factor of the amplifier 26 variable will be described with reference to FIG. FIG.
FIG. 4 is a characteristic diagram showing a relationship between an integration time of a photodiode cell inside a pixel of the CCD 11 and an integration voltage.

In FIG. 2, a shows the characteristic when the subject is bright, and b shows the characteristic when the subject is dark. V _S is the saturation voltage level of the photodiode cell, and V _H is the integration control level when the subject is bright. According to the output of the photometric sensor 22, the CPU 15
The exposure calculation is performed in step (1) to determine the exposure time (integration time) of the CCD 11, and the integration time is determined so that the integration level of the CCD 11 becomes _VH . Therefore, when the subject in FIG. 7A is bright, the integration time is T ₁ .

On the other hand, V _L is an integral control level when the subject is dark. In this case, exposure calculation is performed in the CPU 15 in accordance with the output of the
Is determined, but the integration time is determined so that the integration level of the CCD 11 becomes _VL .

When the subject is dark (shown in b), the integration control level is set to V _{H in the} same manner as when the subject is bright (shown in a).
If you, the integration time T ₂ next becomes considerably longer. Therefore, a problem of camera shake occurs in actual photographing. Therefore, integral control levels by the V _H to V _L, it is possible to shorten the integration time from T ₂ to T _3.

[0028]

[Table 1]

According to the above Table 1, SS ≦ 1 with respect to the shutter speed SS (SS before shift) obtained by the exposure calculation.
/ 30 sec, the integral control level is set to V _H and SS
Is not shifted. Therefore, SS '= SS. Here, SS 'is the actual control shutter time.
The amplification factor of the amplifier 26 is A. 1/30 <SS
Then, the integration control level is set to _VL , and the exposure time SS is shifted. SS ′ = SS × １ ／. Furthermore,
The amplification factor of the amplifier 26 is 4 × A.

FIG. 3 is a circuit diagram showing the internal configuration of the amplifier 26. In FIG. 3, operational amplifiers 261 and 26
The positive input terminal 2 is supplied with the input voltage V _IN from the CCD 21, and the negative input terminal is connected to the connection point of the voltage dividing resistors R 1 and R 2 and the connection point of R 3 and R 4. The output terminals of the operational amplifiers 261 and 262 are connected to the analog switch 263. This analog switch 26
Reference numeral 3 is for selecting the outputs of the operational amplifiers 261 and 262 in accordance with the gain control signal from the CPU 15 and connecting the output to the output terminal V _OUT .

The resistance value of the voltage dividing resistor R3 is the resistor R
1, and the resistance value of the resistor R4 is R4 = 3R1 +
The value is represented by the relational expression of 4R2. Therefore, when the amplification factor is A, the non-inverting amplifier composed of the operational amplifier 261 and the voltage dividing resistors R1 and R2 has a non-inverting amplifier composed of the operational amplifier 262 and the voltage dividing resistors R3 and R4. The rate is 4 × A.

Next, the operation of the digital camera configured as described above will be described. FIG. 4 is a flowchart illustrating an operation sequence according to the first embodiment of this invention.

First, in step S1, the internal memory is initialized by initialization after reset / start. Next, in step S2, the power switch 3
6 is monitored. Here, if the power switch 36 is on, the process proceeds to step S4, and if it is off, the process proceeds to step S3.

In step S3, the display of the operation display section 35 is turned off. If the operation display unit 35 was originally in the OFF state, that state is maintained. afterwards,
The process returns to step S2.

In step S4, the display of the operation display section 35 is turned on, or the display content is updated. Next, in step S5, the high quality mode switch 39 is monitored. Here, if the high quality mode switch 39 is on, the process proceeds to step S6, and if it is off, the process proceeds to step S7.

In step S6, a mode change process is performed. Here, the state of the internal memory corresponding to the high quality mode is switched from the set state to the reset state or from the reset state to the set state. After step S6, the process returns to step S2.

In step S7, the state of the first release switch 37 is monitored. If the first release switch 37 is on, the process proceeds to step S8, and if it is off, the process returns to step S2.

In step S8, distance measurement is performed using the AF sensor 5, and the lens drive amount is calculated based on the distance measurement result. Next, in step S9, the lens driving mechanism 16 is used to drive the lens for focusing.

In step S10, photometry is performed using the photometry sensor 22. Step S1
In step 1, the exposure calculation is performed based on the photometry result, and the aperture value to be controlled, the AV value, and the shutter speed SS are calculated.

Next, in step S12, the aperture is narrowed down by using the aperture drive mechanism 17. Then, in step S13, when the mirror drive circuit 18 is used to perform mirror up, in the next step S14, the front curtain of the focal plane shutter 10 is started using the shutter control circuit 20.

Then, in step S15, it is determined whether or not the front curtain travel has been completed. If the front curtain travel has been completed, the flow proceeds to step S16. In this step S16,
The integration control of the CCD 11 is performed. From the exposure calculation result SS, the shutter speed SS 'of the actual control is obtained according to Table 1 above. In accordance with the shutter time SS ', the timing pulse generating circuit 27 is used to control the integration of the CCD 11.

In the following step S17, the shutter control circuit 20 is used to operate the focal plane shutter 10
The second curtain starts. Then, in step S18, if it is determined that the rear curtain driving has been completed, the process proceeds to step S19.

In this step S19, image data is read from the CCD 11. At this time, the amplifier 26
Is set by a gain control signal from the CPU 15 according to Table 1 above.

In step S20, the aperture opening drive is performed by the aperture driving mechanism 17, and in the following step S21, the mirror driving circuit 18 is used to perform mirror down. Next, in step S22, shutter charging is performed using the shutter charging mechanism 19.

In step S23, the image data is recorded on the image data recording medium 33 by the image recording circuit 32. In step S24, an image is displayed on the image monitor 31 using the image monitor driver 30.

Further, in step S25, it is determined whether the mode is the high quality mode. If the mode is the high quality mode, a subroutine "measurement of dark output" is performed in a succeeding step S26, and thereafter, the process returns to the step S2. In step S25,
If the mode is not the high quality mode, the process returns to step S2.

Next, referring to the flowchart of FIG.
The detailed operation of the subroutine "Dark output measurement" in step S26 of the flowchart of FIG. 4 will be described. First,
In step S31, when the temperature is measured using the temperature sensor 21, in step S32, a determination value (SS1) is input from Table 2 below.

[0048]

[Table 2]

In this embodiment, whether or not the measurement is performed is determined based on the shutter speed SS (before shift) obtained by the exposure calculation and the temperature data near the CCD 11. The criteria for executing the dark output measurement are shown in Table 2 above.
As shown in FIG.

That is, the judgment value SS that differs depending on the temperature
From FIG. 1, in the case of a long time, it is determined that the influence of the dark output is large, and the dark output is measured. Here, the dark output has a greater effect as the exposure time (integration time) is longer, and the degree of the influence is proportional to the exposure time. The dark output is
Depending on the temperature, the magnitude of the dark output doubles as the temperature increases by about 10 degrees. Therefore, depending on the temperature, SS1
Is different.

Next, in step S33, SS determined by the exposure calculation (SS before shift, corresponding to the leftmost row in Table 1) is compared with SS1. Here, if SS ≧ SS1, the process proceeds to step S34; otherwise, the process returns.

In step S34, the shutter 10 is not operated, and the CCD 11 is integrated in a light-shielded state.
The integration time at this time is the same as the exposure time SS 'in step S16 in the flowchart of FIG. That is, the dark output is measured under the same conditions as during the exposure.

In step S35, the dark output data is read out. In step S36, the dark output data is recorded on the image data recording medium 33 by using the image recording circuit 32. Then, return.

[0054]

[Table 3]

[0055]

[Table 4]

Tables 3 and 4 show the data structure when recording image data or dark output data on the image data recording medium 33. Of these, Table 3 shows the structure of the image sensor data for one frame, the details of which are as shown in Table 4.

FIG. 6 is a diagram showing a system for loading the image data recording medium 33 taken out of the camera after shooting and the dark output correction software 51 into the personal computer 50 to perform dark output correction.

As the dark output correction data, the data actually recorded by the user by operating the camera 52 to measure the dark output and recorded on the image data recording medium 33 is used. Next, a sequence of dark output correction software when performing dark output correction using the system shown in FIG. 6 will be described with reference to the flowchart of FIG.

First, in step S41, all image data and all dark output data are read from the image data recording medium 33 and saved on the hard disk of the personal computer 50. Next, at step S42, the loop counter I is set to I = 0, and at step S43, I
The third image data is read.

Then, in step S44, the image sensor data type (see Tables 3 and 4) inside the image data is read. If the type of the read image data is type 1 (with dark output correction data), the process proceeds to step S45, and type 0 (without dark output correction data).
In the case of, the process proceeds to step S48.

Next, in step S45, the corresponding dark output data No. (See Tables 3 and 4), and the corresponding dark output data No. Is read out. Then, in step S46,
Pixel correction is performed. This will be described later in detail with reference to FIG.

In step S47, the corrected image data is saved on the hard disk of the personal computer 50. Then, in step S48, the loop counter I is incremented by +1. Thereafter, step S49
It is determined whether or not all image data has been completed. If all the image data has been completed, the process is terminated; otherwise, the process returns to step S43.

FIG. 8 is a flowchart for explaining the detailed operation of the subroutine "pixel correction" in step S46 of the flowchart of FIG. In this subroutine, dark output correction calculation is performed for each pixel in one image data.

First, in step S51, a loop counter J is set to J = 0. Then, step S52
, The data GD of the J-th pixel in the image data
Data ADATA (J) of the J-th pixel in the corresponding dark output data is subtracted from ATA (J), and the result is converted to data HDATA of the J-th pixel of the corrected pixel data.
(J).

In step S53, the loop counter J
Is added by +1. Then, in step S54, it is determined whether all pixels have been completed. Here, if all pixels have been completed, the process returns. If not, the process returns to step S52.

Next, a modification of the first embodiment will be described. In the first embodiment described above, a special mode for dark output measurement called a high quality (HQ) mode is set. However, the present invention is not limited to this mode. For example, the dark mode is linked with another shooting mode. The output may be measured. For example, you may make it link with the night view mode for imaging a night view. Alternatively, a program photographing mode and a manual photographing mode may be provided so as to be linked when the manual photographing mode is set.

In the first embodiment described above, the dark output measurement is performed in accordance with the exposure time and temperature conditions in addition to the setting of the high quality mode. The dark output measurement may be performed only by the photographing mode regardless of the exposure time or the temperature condition.

Further, in the above-described first embodiment, the dark output measurement is performed according to the exposure time and temperature conditions after setting the high quality mode.
The dark output measurement may be performed only depending on the exposure time or the temperature condition, regardless of the shooting mode such as the high quality mode.

Next, a second embodiment of the present invention will be described. The configuration of the system according to the second embodiment is the same as that of the above-described first embodiment shown in FIG.

FIG. 9 is a flowchart for explaining an operation sequence in the second embodiment. In the flowchart of FIG. 9, steps S61 to S62, steps S64 to S66, step S71, step S7
2 to S87 and steps S90 to S91 are respectively performed in FIG.
Steps S1 and S2, steps S4 and S6, step S3, steps S7 and S22,
Steps S23 and S24 are the same, and a description thereof will be omitted.

If it is determined in step S62 that the power switch 36 is on, the flow advances to step S63 to set the PW flag. On the other hand, step S
If the power switch 36 is off at 62, then the state of the PW flag is determined at step S67.
Here, if the PW flag = 1, that is, if the power switch 36 has changed from the on state to the off state, the process proceeds to step S68, and if not, the process returns to step S62.

In step S68, the PW flag is cleared. Next, in step S69, it is determined whether the mode is the high quality (HQ) mode. As a result, if the mode is the high quality mode, the process proceeds to step S70; otherwise, the process proceeds to step S71.

In step S70, a subroutine "dark output measurement" is executed. Details of this subroutine will be described later with reference to FIG. Step S8
When the shutter charge is performed in step 7, the next step S
At 88, it is determined whether the mode is the high quality mode. Here, if the mode is the high quality mode, the process proceeds to step S89; otherwise, the process proceeds to step S90.

In step S89, the temperature is measured by the temperature sensor 21. Then, in step S90, the image recording circuit 32 is used to
Is recorded.

[0075]

[Table 5]

[0076]

[Table 6]

Tables 5 and 6 show that the image data recording medium 3
3 shows a data structure when recording image data or dark output data. Table 5 shows the structure of the image sensor data for one frame, the details of which are as shown in Table 6.

FIG. 10 is a flowchart for explaining the detailed operation of the subroutine "dark output measurement" of step S70 in the flowchart of FIG. First, in step S101, temperature measurement is performed by the temperature sensor 21. Next, in step S102, the integration time for performing the dark output measurement is set to SSa = 1 sec.

Next, in step S103, the amplifier 26
Is set to a low magnification (amplification factor A). And
In step S104, the shutter 10 is not operated,
In the light-shielded state, integration control of the CCD 11 is performed.

In step S105, the dark output data is read from the CCD 11, and in step S106, the image recording circuit 32 is used to read the dark data.
, Dark output data is recorded.

The data structure for recording the dark output data is as shown in Tables 5 and 6 as described above. A system for performing dark output correction is shown in FIG.
Is the same as that of the first embodiment described above.

The sequence of the dark output correction software for performing the dark output correction using the above system is as shown in FIG. 7 and is the same as that of the first embodiment. Here, the pixel correction processing in step S46 in the flowchart of FIG. 7 is different from that of the first embodiment described above and is as shown in FIG.

FIG. 11 shows a second embodiment of FIG.
40 is a flowchart for describing a detailed operation of a subroutine "pixel correction" of step S46 in the flowchart of FIG.

In step S111, first, the gain data of the amplifier 26 is read out of the image data and monitored. If the gain data is 0 (amplification factor A), the process proceeds to step S113. If the gain data is 1 (amplification factor 4 × A), the process proceeds to step S112.

In step S113, since the amplifier gain is low, the conditions are the same as those of "dark output measurement" in step S103 in the flowchart of FIG.
Second time data SS 'is read from the image data, and S
Sg = SS '.

On the other hand, in step S112, since the amplifier gain is high, the condition is different from the "dark output measurement" of step S103 in the flowchart of FIG. Therefore, here, SSg = SS ′ × 4 to satisfy the same conditions as “dark output measurement”.

Next, in step S114, since the magnitude of the dark output is proportional to the integration time, the scaling factor of the dark output caused by the integration time (the exposure factor relative to the magnitude of the dark output in the dark output measurement) Ratio of the magnitude of the dark output)
F1 is determined by F1 = SSg / SSa.

Then, in step S115, since the magnitude of the dark output is related to the temperature, the scaling factor F2 of the dark output caused by the temperature is F2 = 2 ＾ ｛(TEMP
g-TEMPa) / 10 °. here,
TEMPg is temperature data read from image data (CCD temperature at exposure), and TEMPa is temperature data read from dark output data (CCD at dark output measurement).
CD temperature).

In step S116, the loop counter J
Are set to J = 0. Then, in step S117, the data GDA of the J-th pixel in the image data
The data obtained by multiplying the data ADATA (J) of the J-th pixel by F1 × F2 among the corresponding dark output data from TA (J) is subtracted. The result is the data HDATA of the J-th pixel of the corrected pixel data. (J).

At step S118, the loop counter J
Is added by +1. Then, in step S119, it is determined whether or not all pixels have been completed. here,
If all pixels have been completed, the process returns. If not, the process returns to step S117.

The second embodiment can be modified as follows. In the above-described second embodiment,
Dark output measurement is performed when the power switch is off.
The dark output measurement may be performed when the power switch is turned on.

The structure of the image data is as shown in Tables 5 and 6 above.
Although the shutter time SS 'of the actual control is recorded, the shutter time SS obtained by the exposure calculation may be recorded. According to the above-described embodiment of the present invention, the following structure is provided. Can be obtained.

(1) An image sensor for converting a subject image into an electric signal, a light shielding means for controlling transmission or blocking of subject light to the image sensor, and recording an output signal read from the image sensor. Corresponding to the operation of the exposure device for determining an appropriate exposure condition for the image sensor, performing exposure, and obtaining image data from the image sensor. do it,
The light-shielding unit is in a light-shielding state, a dark output measuring unit for obtaining dark output data from the image sensor, and a photographing execution unit that operates both the exposure unit and the dark output measuring unit in response to a release operation. A digital camera comprising:

(2) An image sensor for converting a subject image into an electric signal, light shielding means for controlling transmission or blocking of subject light to the image sensor, and recording an output signal read from the image sensor. Corresponding to the operation of the exposure device for determining an appropriate exposure condition for the image sensor, performing exposure, and obtaining image data from the image sensor. do it,
A dark output measuring unit for obtaining dark output data from the image sensor by setting the light shielding unit in a light shielding state, a first photographing mode in which only the exposure unit operates in response to the release operation, and a response to the release operation A photographing execution unit having a second photographing mode for operating both the exposure unit and the dark output measuring unit; and a photographing mode switching unit for switching the first photographing mode and the second photographing mode. A digital camera.

(3) In a digital camera having an electronic image pickup device for converting a subject image into an electric signal, an exposure means for exposing the image pickup device and obtaining image data from the image pickup device; A light-shielding unit that controls transmission or blocking of subject light to the image sensor, a recording unit that records image data obtained from the image sensor, a first shooting mode in which only the exposure operation of the exposure unit is performed, A mode switching unit that switches between an operation for obtaining dark output data from an output of the image sensor and a second shooting mode for performing both an exposure operation of the exposure unit in a state where the light is shielded by the light shielding unit. And a digital camera.

(4) The first shooting mode and the second shooting mode
Further comprising mode setting means for setting any one of the photographing modes, wherein the mode switching means switches to one of the first photographing mode and the second photographing mode in accordance with a signal from the mode setting means. The digital camera according to the above (3), wherein the digital camera is switched.

(5) The recording means, when recording the image data and the dark output data, identifies data for identifying whether the data is the image data or the dark output data. The digital camera according to (3), wherein recording is performed.

(6) The recording means records, when recording the image data and the dark output data, data indicating a correspondence for identifying which image data the dark output data is used for. The digital camera according to the above (3) or (5), wherein

(7) In a digital camera having an electronic image pickup device for converting a subject image into an electric signal, an exposure means for exposing the image pickup device and obtaining image data from the image pickup device; Light blocking means for controlling transmission or blocking of subject light to the image sensor, recording means for recording image data obtained from the image sensor, and light blocking by the light blocking means in conjunction with the exposure operation of the exposure means A digital camera, comprising: dark output measuring means for measuring dark output data from the output of the image sensor; and command means for outputting an operation signal to the dark output measuring means.

(8) The digital camera according to (7), wherein the command means outputs an operation signal to the dark output measuring means by operating a camera operation member.

(9) The digital camera according to (8), wherein the operation member of the camera is a power switch. (10) The recording means, when recording the image data and the dark output data, records identification data for identifying whether the data is the image data or the dark output data. The digital camera according to (7), wherein:

(11) When recording the image data and the dark output data, the recording means records data indicating a correspondence for identifying which image data the dark output data is used for. The digital camera according to the above (7) or (10), wherein

(12) The apparatus further comprises a temperature measuring means for measuring a temperature in the vicinity of the image pickup device, wherein the recording means also records the temperature at the time of photographing when recording the image data and the dark output data. The digital camera according to the above (7) or (11), wherein

(13) Further, there is provided a measuring means for measuring the photographing time at the time of photographing, wherein the recording means records the photographing time when recording the image data and the dark output data. Characteristic (7) or (11) above
A digital camera according to claim 1.

[0105]

As described above, according to the present invention, it is possible to provide a digital camera capable of reducing the time required for the calculation for correcting the dark output in the waiting time during photographing.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital camera, showing a configuration of a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an integration time and an integration time of a photodiode cell inside a pixel of the CCD 11 of FIG.

FIG. 3 is a circuit diagram showing an internal configuration of the amplifier 26 of FIG.

FIG. 4 is a flowchart illustrating an operation sequence according to the first embodiment of this invention.

FIG. 5 is a flowchart illustrating a detailed operation of a subroutine “dark output measurement” in step S26 of the flowchart in FIG. 4;

FIG. 6 is a diagram showing a system for loading an image data recording medium 33 taken out of a camera after shooting and dark output correction software 51 into a personal computer 50 to perform dark output correction.

FIG. 7 is a flowchart illustrating a sequence of dark output correction software when performing dark output correction using the system shown in FIG. 6;

8 is a flowchart illustrating a detailed operation of a subroutine “pixel correction” in step S46 of the flowchart in FIG. 7;

FIG. 9 is a flowchart illustrating an operation sequence according to the second embodiment of the present invention.

FIG. 10 is a step S7 in the flowchart of FIG. 9;
10 is a flowchart for explaining a detailed operation of a subroutine “Dark output measurement” of 0;

FIG. 11 is a flowchart illustrating a detailed operation of a subroutine “pixel correction” in step S46 in the flowchart of FIG. 7 in the second embodiment.

[Explanation of symbols]

Reference Signs List 1 shooting lens, 2 aperture, 3 quick return mirror, 5 AF sensor, 10 focal plane shutter, 11 CCD, 15 CPU, 16 lens drive mechanism, 17 aperture drive mechanism, 18 mirror drive circuit, 19 shutter charge mechanism, 20 shutter control Circuit, 21 temperature sensor, 22 photometric sensor, 25 image data controller, 26 amplifier (AMP), 27 timing pulse generation circuit, 28 A / D conversion circuit, 29 image memory, 30 image motor driver, 31 image monitor, 32 image recording Circuit, 33 image data recording medium, 35 operation display section, 36 power switch (PW SW), 37 first release switch (1R SW), 38 second release switch (2R SW), 39 high quality mode switch (HQM) S
W), 40 dark output measurement start switch (ANS SW), 50 personal computer, 51 dark output correction software, 52 camera.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/928 H04N 5/92 J F term (Reference) 5C021 PA17 PA72 PA92 YA03 YA08 5C022 AA13 AB17 AB20 AB37 AB38 AC42 AC69 5C024 AA01 BA01 CA00 CA06 EA01 FA01 FA09 FA11 GA11 HA10 5C052 GA02 GB01 GC08 5C053 FA08 KA04 LA02

Claims (3)

[Claims] 1. A digital camera having an electronic image pickup device for converting a subject image into an electric signal, wherein the exposure device exposes the image pickup device and obtains image data from the image pickup device. A light-shielding unit that controls transmission or light-shielding of subject light to an image sensor; and a recording unit that records image data obtained from the image sensor. The light-shielding unit interlocks with an exposure operation of the exposure unit. A digital camera which measures dark output data from the output of the image sensor and records both image data and dark output data in the recording means. 2. A digital camera having an electronic image pickup device for converting a subject image into an electric signal, comprising: an exposure unit for exposing the image pickup device to obtain image data from the image pickup device; Light-shielding means for controlling transmission or shading of subject light to the image sensor; dark output measuring means for measuring dark output data from an output of the image sensor in a state where light is shielded by the light-shielding means; Recording means for recording image data; a first photographing mode for performing only the exposure operation of the exposure means; and a second photographing mode for performing both the measurement of the dark output correction data by the dark output measurement means and the exposure operation of the exposure means. And a mode switching means for switching between the photographing modes. 3. The digital camera according to claim 2, wherein said mode switching means switches between a first photographing mode and a second photographing mode according to photographing conditions.