JP3960790B2 - SHUTTER DELAY ADJUSTING METHOD AND IMAGING DEVICE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shutter delay adjusting method for adjusting delay variation (mechanical difference) of an optical shutter represented by a mechanical shutter, and an image pickup apparatus to which the method is applied, and in particular, the adjustment can be made by several exposure operations. The present invention relates to a shutter delay adjustment method and an imaging apparatus to which the method is applied.
[0002]
[Prior art]
In recent years, a subject image is imaged on a solid-state image sensor such as a CCD two-dimensional image sensor by an imaging optical system and converted into an electrical signal, and the obtained imaging data is recorded on a recording medium such as a semiconductor memory or a magnetic disk. So-called electronic cameras are becoming widespread.
[0003]
Many of these types of electronic cameras use an electronic shutter and a mechanical shutter together to control the exposure time in the image sensor. For example, Japanese Patent Application Laid-Open No. 11-234574 discloses a technique for adjusting the delay variation of the mechanical shutter. Compares the exposure amount during the operation of the pure electronic shutter and the exposure result during the operation of the main shutter (combined with the mechanical shutter), and repeats the trial operation until the difference becomes 0 to obtain the exposure amount corresponding to the predetermined exposure time. A method is disclosed.
[0004]
[Problems to be solved by the invention]
By the way, in the method disclosed in Japanese Patent Application Laid-Open No. 11-234574, it is necessary to repeatedly perform the shutter operation until the difference from the pure electronic shutter operation becomes zero, so that a long adjustment time is required. was there. For example, if ± 100 μs is increased / decreased in increments of 5 μs, trials of about 10 to 30 times are required for absorbing variations up to 20 times + each time.
[0005]
The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a shutter delay adjustment method that can be adjusted by several exposure operations and an imaging apparatus to which the method is applied.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides an image sensor that photoelectrically converts a subject image, shutter means that blocks subject image input to the image sensor, and a substantial exposure start time of the image sensor. A shutter delay adjusting method for an image pickup apparatus having exposure control means capable of variably setting a shutter close command output timing, which is a time until a close command is output to the shutter means, and is substantially controlled by closing the shutter means. A first exposure amount detecting step for detecting a first exposure amount given to the image sensor at the time of first imaging for ending the exposure; and a second image capturing for substantially ending the exposure by element shutter control in the image sensor. A second exposure amount detecting step for detecting a second exposure amount sometimes given to the image sensor, and the detected first and second exposure amounts Based on this, a delay time for calculating an equivalent shutter delay time which is an equivalent delay time from the time when a closing command is output to the shutter means to the time when a substantial exposure is completed by closing the shutter means. a calculation step possess, the first exposure amount detection step, the first imaging multiple runs, the delay time calculation step, for each of the first exposure, the its exposure first The equivalent shutter delay which is an equivalent delay time from the time when the closing command is output to the shutter means to the time when the substantial exposure end time is achieved by closing the shutter means based on the exposure amount of 2 The time is calculated, and an average value of the calculated plurality of equivalent shutter delay times is calculated .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0010]
(First embodiment)
First, a first embodiment of the present invention will be described.
[0011]
FIG. 1 is a block diagram showing a configuration of a digital camera which is an adjusted camera of the shutter delay adjustment system according to the first embodiment.
[0012]
In the figure, 101 is an imaging lens system composed of various lenses, 102 is a lens driving mechanism for driving the lens system 101, 103 is an exposure control mechanism for controlling the aperture and mechanical shutter of the lens system 101, and 104 is low-pass and red. An outer cut filter 105 is a CCD color image pickup device for photoelectrically converting a subject image, 106 is a CCD driver for driving the image pickup device 105 including an electronic shutter, 107 is a pre-driver including an A / D converter and the like. A process circuit 108 is a digital process circuit for performing various digital arithmetic processing such as γ conversion, 109 is a card interface, 110 is a memory card, and 111 is an LCD image display system. The CCD 105 is a so-called interlaced readout type image sensor. For this reason, a mechanical shutter combined frame shutter is used to read out information of all pixels simultaneously and independently at the time of actual imaging. Further, the CCD 105 can perform pure electronic shutter drive in a so-called field accumulation mode (vertical resolution 1/2 (pixel number halving) total pixel readout obtained by adding two lines on the image sensor), and this shutter delay adjustment system Performs the delay adjustment of the mechanical shutter using the frame shutter combined with the mechanical shutter and the pure electronic shutter in the field accumulation mode. When the field accumulation mode is used, for example, color information cannot be obtained with a single-plate color element using a Bayer array. However, this delay adjustment requires only an exposure amount, and this is a particular problem including such cases. Will not occur.
[0013]
In the figure, 112 is a system controller for comprehensively controlling each part, 113 is an operation switch system composed of various SWs, 114 is an operation display system for displaying an operation state and a mode state, and 115 is a light emitting means. , 116 is a lens driver for controlling the lens driving mechanism 102, 117 is an exposure control driver for controlling the exposure control mechanism 103 and the strobe 115, and 118 is a nonvolatile memory for storing various setting information. (EEPROM) 119 indicates a communication control circuit for communicating with other electronic devices including an external adjuster described later. The delay adjustment of the mechanical shutter in this digital camera is controlled by the delay time setting unit 112a of the system controller 112.
[0014]
On the other hand, FIG. 2 is a block diagram showing a configuration of a personal computer which is an external adjuster of the shutter delay adjusting system according to the first embodiment.
[0015]
In the figure, 201 is a CPU for overall control of each part, 202 is a system memory serving as the main memory of the computer, 203 is a magnetic disk device serving as an external storage of the computer, and 204 is a user interface output in the computer. Reference numeral 205 denotes a display controller, 205 denotes a keyboard controller that controls input of a user interface in the computer, and 206 denotes a communication control circuit for communicating with other electronic devices including the above-described digital camera. Further, the display controller 204 controls display of the display data created by the CPU 201 on the CRT 204a and LCD 204b, and the keyboard controller 205 transmits the operation of the keyboard 205a and mouse 205b to the CPU 201. The shutter delay adjustment system is composed of various programs including an exposure amount detection program and a delay time calculation program that are loaded from the magnetic disk device 203 to the system memory 202 and executed by the CPU 201.
[0016]
Next, the operation principle of the mechanical shutter delay adjustment executed by the shutter delay adjustment system will be described.
[0017]
First, the operation of the digital camera during actual shooting will be described. FIG. 3 is a timing chart showing the operation of the digital camera during actual photographing.
[0018]
After the previous CCD read-out, the system controller 112 outputs a mechanical shutter command (open) to the exposure control driver 117 (FIG. 3 (1)). In response to this, the exposure control driver 117 drives the exposure control mechanism 103 to open the mechanical shutter of the lens system 101. Next, the system controller 112 commands the CCD driver 106 to output a final charge discharge pulse (FIG. 3 (2)). In response to this, the CCD driver 106 superimposes and applies the final charge discharge pulse to the substrate bias voltage of the CCD 105 in order to execute the charge discharge of the pixel portion. This time is a substantial opening point at the time of actual photographing (substantial opening timing). Note that the charge discharge pulse itself can be applied at any timing before that, and in the actual mode, a periodic pulse application is often adopted. In this discussion, only the “final” charge ejection pulse is taken into account because only the final pulse timing is intrinsically significant.
[0019]
Thereafter, the system controller 112 outputs a mechanical shutter command (closed) to the exposure control driver 117 (FIG. 3 (3)). Here, the time until the mechanical shutter command (close) is output from the previous substantial opening time is referred to as shutter close command output timing (T). In response to this, the exposure control driver 117 drives the exposure control mechanism 103 to close the mechanical shutter of the lens system 101. Further, the mechanical shutter of the lens system 101 is actually closed after a predetermined delay time.
[0020]
It is unclear how the light quantity changes when the mechanical shutter is closed. Of course, since there are machine differences, a specific shape cannot be assumed as shown in FIG. However, since only the amount of light is essential for exposure control, the closing time in the virtual situation where the closing was performed ideally (instantaneously) (the time when the graph areas are equal in the figure) is substantially closed. It is the time of formation (substantial closing timing). The time from the output of the mechanical shutter command (close) to the substantial closing time is the equivalent delay time (Td).
[0021]
Finally, the system controller 112 sequentially outputs a 1st field readout signal and a 2nd field readout signal to the CCD driver 106, and executes interlace readout of the subject image.
[0022]
Next, how the equivalent delay time appearing during the operation at the time of the actual photographing is obtained by the shutter delay adjustment system will be described.
[0023]
Here, it is assumed that the digital camera is under a stable light source when calculating the equivalent delay time. Further, it is assumed that the variation of the mechanical shutter closing time every time is sufficiently small and can be ignored.
[0024]
First, photographing for shutter delay adjustment is instructed from a personal computer that is an external adjuster to a digital camera that is a camera to be adjusted. More specifically, the personal computer outputs a mechanical shutter close command after a substantial exposure start, for example, 1/1000 second (T1), and after a substantial exposure start, this time 1/1000. The digital camera is instructed to take two shots by the second exposure that closes the element shutter of the CCD 105 after a second (T1). (Note that the element shutter (pure electronic shutter) driving itself used in the second exposure is a well-known technique and will not be described in detail. However, the timing of the charge phase from the pixel portion of the CDD 105 to the transfer path is substantially the shutter closing timing. Therefore, the second exposure can be performed by adjusting any timing of opening the shutter by applying the final charge discharge pulse and closing the shutter by the charge phase from the pixel portion to the transfer path. In response to this, in the digital camera, the delay time setting unit 112a of the system controller 112 executes the instructed two shootings. FIG. 4 is a diagram schematically showing the first exposure and the second exposure. Then, the delay time setting unit 112a transmits the two subject images obtained by this shooting to the personal computer.
[0025]
On the other hand, in the personal computer that has received these two subject images, the exposure amount detection program has the first exposure amount (Sm) from the subject image at the time of the first photographing and the second exposure amount from the subject image at the time of the second photographing. (Se) is calculated. When the first exposure amount and the second exposure amount are calculated, the delay time calculation program calculates the equivalent delay time from the two exposure amounts according to the following principle.
[0026]
Using the symbols shown in FIG.
Sm = S1 + S0 (1) Equation Se = S1 (2) Equation can be expressed.
[0027]
From the equations (1) and (2),
S0 = Sm-Se
Can be derived,
Equivalent delay time Td = T1. (S0 / S1) = T1. (Sm-Se) / Se
Can be obtained as
[0028]
The equivalent delay time calculated by this delay time calculation program is transferred from the personal computer to the digital camera. On the other hand, in the digital camera, the delay time setting unit 112 a of the system controller 112 stores the transferred equivalent delay time in the EEPROM 118. The equivalent delay time stored in the EEPROM 118 is used when setting the shutter close command timing at the time of actual photographing. The shutter close command timing may be obtained by subtracting the equivalent delay time from the scheduled exposure time. Further, since this shutter close command timing is the time from the substantial opening time until the mechanical shutter command (close) is output, the adjustment outputs the time when the final charge discharge pulse is output and the mechanical shutter command (close). It is possible by moving any of the time points.
[0029]
Next, with reference to FIGS. 5 to 7, the operation procedure of the delay adjustment of the mechanical shutter executed by the shutter delay adjustment system will be described.
[0030]
First, in order to compare with this shutter delay adjustment system, the operation procedure in the conventional shutter delay adjustment method will be described with reference to FIG.
[0031]
In the conventional shutter delay adjustment method, first, the exposure amount during the pure electronic shutter operation is acquired (step A1). Next, after setting a shutter close command output timing set in advance as an initial value, an exposure amount during the main shutter operation using the mechanical shutter is acquired (step A2).
[0032]
When these two exposure amounts are obtained, it is checked whether or not the values match (step A3). If they do not match (NO in step A3), it is checked which exposure value is larger. (Step A4). If the exposure value during the shutter operation is larger (YES in step A4), the shutter close command output timing is set to one step faster (step A5), and the processing from step A2 is repeated. On the other hand, if the exposure value during the pure electronic shutter operation is larger (NO in step A4), the shutter close command output timing is set to one step low speed (step A6), and the processing from step A2 is repeated.
[0033]
If the two exposure values match (YES in step A3), the shutter close command output timing at this time is registered as the shutter speed (step A7), and the process is terminated.
[0034]
FIG. 6 is a flowchart showing an operation procedure for calculating an equivalent delay time, which is a time from when the shutter delay adjusting system of the present embodiment outputs a mechanical shutter command (closed) until a substantial closing time.
[0035]
In this shutter delay adjustment system, first, a predetermined first shutter close command output timing is set, and then the exposure amount during the main shutter operation with the mechanical shutter is acquired (step B1). Subsequently, the exposure amount at the time of the pure electronic shutter operation is acquired (step B2).
[0036]
Then, an equivalent delay time is calculated based on the two acquired exposure amounts (step B3), and the calculated equivalent delay time is stored in the EEPROM (step B4).
[0037]
FIG. 7 is a flowchart showing an operation procedure when the shutter delay adjustment system determines the shutter close command output timing.
[0038]
When determining the shutter close command output timing, first, the equivalent delay time stored in the EEPROM is read (step C1). Then, the shutter close command output timing is calculated by subtracting the read equivalent delay time from the scheduled exposure time (step C2).
As described above, compared with the conventional shutter delay adjusting method shown in FIG. 5, the shutter delay adjusting method of the shutter delay adjusting system shown in FIGS. 6 and 7 can obtain the desired result of the shutter operation. There is no need to repeat the above, and the present shutter (mechanical shutter) has an advantage that it can be performed only once.
[0039]
(Second Embodiment)
Next explained is the second embodiment of the invention.
[0040]
In the first embodiment described above, data is obtained by only two exposures (imaging), but it is assumed that there is no variation in operation every time. On the other hand, in the second embodiment, taking this variation into consideration, the number of times of the first exposure, that is, the main shutter operation is increased to take an average. (The second exposure, that is, the exposure using a pure electronic shutter may be performed only once.) This greatly improves the accuracy of the adjustment.
[0041]
Furthermore, in consideration of the existence of such an operation variation every time, when using a repeated trial loop as in the conventional adjustment method, the loop does not end stably due to the occurrence of hunting due to the operation variation. Although the problem of being unable to be adjusted may occur, in the first and second embodiments, such a problem does not occur, which is one of the effects of the present invention.
[0042]
In the first and second embodiments, an example has been described in which the exposure amount at the time of shutter delay adjustment and the delay time calculation are performed by the external adjuster. However, these functions are mounted on the digital camera side. It doesn't matter. In this case, as shown in FIG. 8, the system controller 112 may include an exposure amount detection unit 112b and a delay time calculation unit 112c to detect the exposure amount and calculate the delay time when adjusting the shutter delay (EEPROM). The delay time calculation unit 112c stores the data in (1). Further, regarding the shutter delay adjustment, the communication control circuit 119 for communicating with other electronic devices is not necessary.
[0043]
In the above description, 1/1000 s is exemplified as the shutter close command output timing T1 at the time of adjusting the shutter delay, but any value can be used. Therefore, for example, in the case of a shutter that can be adjusted in increments of 64 μs, it is only necessary to set the shutter close command output timing in consideration of the value, and there is no problem in applying this shutter delay adjustment method to a digital camera equipped with this type of shutter. It is possible.
[0044]
Further, since the equivalent delay time generally depends on the aperture (aperture value), it goes without saying that the above-described actual measurement and value writing are preferably performed for each aperture value. Further, for example, the mechanical shutter can be replaced with any optical shutter including a physical shutter such as a liquid crystal or electro-optical ceramic (PLZT or the like).
[0045]
This shutter delay adjustment method can be applied not only to interlaced driving but also to non-interlaced driving. Furthermore, the application of the results obtained thereby is only possible when an electronic shutter and a mechanical shutter are used together. Of course, the case of pure mechanical shutter driving is also effective.
[0046]
That is, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.
[0047]
【The invention's effect】
As described above in detail, according to the present invention, for example, two shutter operations of the first imaging by the main shutter (combined with the mechanical shutter) and the second imaging by the pure electronic shutter operation are performed, and the exposure result thereof. By acquiring the equivalent delay time of the mechanical shutter from the two photometric outputs by calculation, the mechanical shutter delay is adjusted in principle by two exposure operations, even if considering the absorption of variations every time. Make it possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital camera that is an adjusted camera of a shutter delay adjustment system according to an embodiment of the present invention.
FIG. 2 is an exemplary block diagram showing a configuration of a personal computer which is an external adjuster of the shutter delay adjusting system according to the embodiment;
FIG. 3 is a timing chart showing an operation at the time of actual photographing of the digital camera of the embodiment.
FIG. 4 is a view schematically showing first exposure and second exposure handled by the shutter delay adjustment system of the embodiment.
FIG. 5 is a flowchart showing an operation procedure in a conventional shutter delay adjustment method.
FIG. 6 is a flowchart showing an operation procedure when an equivalent delay time, which is a time from when the shutter delay adjustment system of the embodiment outputs a mechanical shutter command (closed) to when the shutter is substantially closed, is calculated.
FIG. 7 is a flowchart showing an operation procedure when the shutter delay adjustment system of the embodiment determines a shutter close command output timing;
FIG. 8 is a block diagram showing a configuration of the digital camera when the exposure amount is detected and the delay time is calculated by the digital camera in the shutter delay adjustment system of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Lens system 102 ... Lens drive mechanism 103 ... Exposure control mechanism 104 ... Filter system 105 ... CCD color image sensor 106 ... CCD driver 107 ... Pre-process circuit 108 ... Digital process circuit 109 ... Card interface 110 ... Memory card 111 ... LCD image Display system 112 ... System controller 112a ... Delay time setting unit 112b ... Exposure amount detection unit 112c ... Delay time calculation unit 113 ... Operation switch system 114 ... Operation display system 115 ... Strobe 116 ... Lens driver 117 ... Exposure control driver 118 ... Nonvolatile memory (EEPROM)
119: Communication control circuit 201: CPU
202 ... System memory 203 ... Magnetic disk device 204 ... Display controller 204a ... CRT
204b ... LCD
205 ... Keyboard controller 205a ... Keyboard 205b ... Mouse 206 ... Communication control circuit

Claims (8)

An image sensor that photoelectrically converts a subject image, a shutter unit that blocks input of the subject image to the image sensor, and a time from the start of substantial exposure in the image sensor until a closing command is output to the shutter unit. A shutter delay adjustment method for an imaging apparatus having exposure control means capable of variably setting a certain shutter close command output timing,
A first exposure amount detecting step for detecting a first exposure amount given to the image sensor at the time of the first imaging for ending substantial exposure by closing the shutter means;
A second exposure amount detecting step of detecting a second exposure amount given to the image sensor at the time of the second imaging in which substantial exposure is ended by element shutter control in the image sensor;
Based on the detected first and second exposure amounts, an equivalent delay time from the time when a closing command is output to the shutter means to the time when a substantial exposure is completed by closing the shutter means. have a delay time calculation step of calculating an equivalent shutter delay time is,
The first exposure amount detection step executes the first imaging a plurality of times,
The delay time calculating step is performed by closing the shutter unit from the time when the closing command is output to the shutter unit based on the exposure amount and the second exposure amount for each first exposure amount. An equivalent shutter delay time that is an equivalent delay time until the substantial exposure end time is calculated, and an average value of the calculated plurality of equivalent shutter delay times is calculated. Method for adjusting shutter delay of apparatus.   2. The shutter delay adjustment method for an image pickup apparatus according to claim 1, further comprising a command output timing setting step for setting the shutter close command output timing to be used at the time of actual imaging based on the calculated equivalent shutter delay time.   3. The shutter delay adjusting method for an image pickup apparatus according to claim 1, further comprising a delay time storing step of storing the calculated equivalent shutter delay time in an EEPROM of the image pickup apparatus. The second exposure amount detecting step detects the second exposure amount by executing the second imaging only once, and the delay time calculating step is based on the plurality of equivalent shutters. 4. The shutter delay adjustment method for an image pickup apparatus according to claim 1, wherein an average value of the delay times is calculated . An image sensor that photoelectrically converts a subject image;
Shutter means for blocking subject image input to the image sensor;
Exposure control means capable of variably setting a shutter close command output timing which is a time from the start of substantial exposure in the image sensor to the output of a close command to the shutter means;
Exposure amount detecting means for detecting an exposure amount given to the image sensor based on an output signal of the image sensor;
The first exposure amount detected by the exposure amount detection means at the time of the first imaging for ending substantial exposure by closing the shutter means, and the second for ending substantial exposure by element shutter control in the imaging element. Based on the second exposure amount detected by the exposure amount detection means at the time of imaging, from the time when the closing command is output to the shutter means to the substantial exposure end time made by closing the shutter means Delay time calculating means for calculating an equivalent shutter delay time which is an equivalent delay time until ,
The first exposure amount detection means performs the first photographing a plurality of times,
The delay time calculation means performs the closing of the shutter means from the time when the closing instruction is output to the shutter means based on the exposure amount and the second exposure amount for each first exposure amount. An equivalent shutter delay time that is an equivalent delay time until the substantial exposure end time is calculated, and an average value of the calculated plurality of equivalent shutter delay times is calculated. apparatus.   6. The apparatus according to claim 5, further comprising command output timing setting means for setting the shutter close command output timing used at the time of actual imaging based on the equivalent shutter delay time calculated by the delay time calculation means. Imaging device.   7. The imaging apparatus according to claim 5, further comprising: an EEPROM; and a delay time storage unit that stores the equivalent shutter delay time calculated by the delay time calculation unit in the EEPROM. The second exposure amount detection means detects the second exposure amount by executing the second imaging only once, and the delay time calculation means, based on this, the plurality of equivalent shutters. The imaging apparatus according to claim 5, 6 or 7, wherein an average value of the delay time is calculated .

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