JP4208510B2 - Focusing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal storage device using a signal storage type sensor or a focus adjustment device that uses the device to obtain a distance measurement or defocus amount and performs focus.
[0002]
[Prior art]
Conventionally, various proposals have been made for a charge storage type photoelectric conversion device, and a range finding device to which this has been applied has already been made.
[0003]
In the distance measuring apparatus as described above, generally, a photoelectric conversion device includes a plurality of photoelectric conversion elements arranged at a predetermined pixel pitch, a charge storage unit corresponding to each photoelectric conversion element, a circuit for controlling charge storage, a photoelectric A circuit for reading the output is configured on one semiconductor chip.
[0004]
A schematic diagram of such a distance measuring apparatus is shown in FIG.
[0005]
In FIG. 2, 201 is a first light receiving lens that forms a first optical path, and 202 is a second light receiving lens that forms a second optical path.
[0006]
A photoelectric conversion device 200 includes a sensor array, a signal storage unit, a peak detection unit, and a signal output unit, which will be described later.
[0007]
Reference numeral 203 denotes a first sensor array in which a plurality of photoelectric conversion elements are linearly arranged, 204 denotes a second sensor array, and 205 denotes a first signal storage unit. The converted electric charge is converted into a voltage and accumulated for each pixel. Further, the signal accumulated in the signal accumulation unit 205 can be cleared by the RES pulse. Reference numeral 206 denotes a second signal storage unit, which converts the charge photoelectrically converted by the second sensor array 202 into a voltage and stores it for each pixel in the same manner as the first storage unit.
[0008]
Further, the sensor array includes pixels shielded by aluminum (hereinafter referred to as dark pixels). The dark pixels are also accumulated and used for a PKMON signal, which will be described later, and a reference signal for the signal level of each pixel.
[0009]
A peak detection unit 207 detects the MAX value of the signal accumulation level of each pixel of the first signal accumulation unit 205 and the second signal accumulation unit 206, and outputs a difference from the dark pixel signal as a PKMON signal. Reference numeral 210 denotes a first signal output unit that sequentially outputs signals corresponding to the respective pixels of the first signal storage unit as an OUT signal by a CLK1 pulse. Reference numeral 211 denotes a second signal output unit which, like the first signal output unit 210, sequentially outputs a signal corresponding to each pixel of the second signal storage unit as an OUT signal using a CLK2 pulse.
[0010]
The accumulation operation and signal readout operation of the distance measuring apparatus of FIG. 2 will be described with reference to the timing chart of FIG.
[0011]
First, the signals in the first signal storage unit 205 and the second signal storage unit 206 are cleared by the RES pulse L → H. At this time, the voltage levels of the dark pixel and other pixel signals are clamped to the reset voltage Vres. Then, after a predetermined time, the RES pulse is changed from H → L, the ST pulse is changed from H → L, and signal accumulation is permitted to start the accumulation operation.
[0012]
FIG. 6 shows the luminance distribution on the sensor arrays 203 and 204, and it is assumed that the signal increases as the intensity of the received luminance increases. The sensor array 203 includes photoelectric conversion elements L1 to L10, and the sensor array 204 includes R1 to R10. FIG. 4A shows an image signal on the sensor array 203, and FIG. 4B shows an image signal on the sensor array 204. FIG. In FIG. 6A, a received light image is formed over L3 to L7, and in FIG. 5B, a received light image is formed over R4 to R8.
[0013]
During the accumulation operation, the signal level of the pixel (L5, R6) having the highest luminance (hereinafter referred to as the peak level) in which the voltage level of the signal accumulation unit decreases with a gradient corresponding to the amount of incident light for each pixel of the sensor array. Vpk is the lowest output among the signal accumulation levels corresponding to each pixel. On the other hand, the signal level Vdk (hereinafter referred to as the dark level) of the dark pixel is shielded from light, so that even when the accumulation operation is started, it hardly falls from around Vres. The peak detection unit 207 detects the peak level Vpk and the dark level Vdr, and outputs a differential voltage between them as a PKMON signal.
[0014]
The PKMON signal level rises at almost the same rate as the voltage drop of the peak level Vpk, A / D conversion is performed by an A / D conversion converter built in a control unit (not shown), and the level is checked by the control unit. .
[0015]
Then, when the PKMON signal level exceeds the accumulation stop level Vcomp, the ST pulse is changed from L to H, thereby completing the accumulation operation in the first signal accumulation unit 205 and the second signal accumulation unit 206. At the same time, the accumulated signal level of each pixel is held.
[0016]
After the accumulation operation is completed, the accumulation signal is read out. Here, when a CLK1 pulse is first input as a readout clock, the signals of the respective pixels of the first sensor array 203 are sequentially output to OUT. When the output of all the pixel signals of the first sensor array 203 is completed, the signal of each pixel of the second sensor array 204 is sequentially output to OUT by inputting the CLK2 pulse.
[0017]
At this time, the OUT signal is based on the dark level, and similarly to the PKMON signal, the output of each pixel is output as a difference signal from the dark level.
[0018]
A control unit (not shown) A / D-converts the output signal in synchronization with the CLK pulse and stores it in the memory in the internal control unit. When the readout of the accumulated signal for all pixels is completed, the readout is performed. End the operation.
[0019]
Based on the principle of triangulation based on the relative value of the image signal of the object to be measured obtained on the first sensor array 203 and the image signal of the object obtained on the second sensor array 204 as described above. Find the distance to the subject.
[0020]
In the above description, the reason why the PKMON signal and the output signal of each pixel are based on the dark level is to cancel the dark current generated during the accumulation operation by subtracting the dark level from each signal.
[0021]
[Problems to be solved by the invention]
Usually, the photoelectric conversion device is formed on a semiconductor chip, and the chip surface is shielded by a light shielding material such as aluminum so that light does not enter other than the sensor array, and charges are generated by the photoelectric conversion action other than the sensor array. Never do. However, the side of the chip is not shielded, so if the brightness of the subject and its surroundings is very high, the incident charge leaks into the sensor array and signal storage unit when light enters from the side of the photoelectric conversion device. Unnecessary charges are accumulated.
[0022]
An image signal in the case where unnecessary charges are accumulated by the incidence of light from the side surface of the photoelectric conversion device will be described with reference to FIGS.
[0023]
In FIG. 8, the accumulation operation start is started by the same operation as in FIG. Normally, in the peak detection unit 207, the signal level of the pixel (L4, R5) with the highest luminance becomes the peak level Vpk, but the pixel signal with large charge leakage, here the pixel signals of L1, R10 are the peak level Vpk. Is output as Therefore, the accumulation is stopped by the pixel signal in which the charge leaks. In this case, the image signal due to the leaked charge is added, and the correct image signal of the subject cannot be detected. In addition, the voltage level of the dark level also drops due to the leakage of charges into the dark pixels.
[0024]
When ranging is calculated based on such an image signal, erroneous ranging is performed.
[0025]
Next, FIG. 9 illustrates an image signal in a state where charge leakage is larger than that in the case of FIG.
[0026]
When the charge leakage is larger, the amount of leakage to the dark pixel is also increased. Therefore, since the fall of the dark level Vdk becomes large, the rate of increase of the PKMON signal, which is the difference signal between the peak level and the dark level, becomes smaller than the rate of decrease of the peak level Vpk. Further, when both the peak level and the dark level reach the saturation level (0V), the PKMON signal becomes the minimum level of 0V.
[0027]
Normally, if the PKMON signal is small even after a predetermined time and does not exceed the accumulation stop level, it is determined that the subject brightness is low and no signal is obtained, and the accumulation operation is stopped. In the state of FIG. 9, the pixel signals of all the sensor arrays including the dark pixels reach the saturation level, the output signal based on the dark level becomes 0 V, and no image signal is obtained at all. In this way, when the amount of charge leakage is large, luminance information of the subject cannot be obtained, and even though the subject luminance is high, an image signal cannot be obtained as in the dark. .
[0028]
In addition, in order to reduce the effect of charge leakage due to incident light from the side surface of the chip, there is a method in which the distance from the signal storage unit to the chip end is sufficiently separated, but the chip area increases and the cost increases. The problem of becoming higher arises.
[0029]
Further, in a distance measuring device using a light receiving means including a plurality of photoelectric conversion elements in Japanese Patent Application Laid-Open No. 09-229673, electric charges gradually leak to a transfer stage CCD (ring CCD, etc.) due to dark current or external light components. However, the method described in the above publication does not correct the leakage of charge due to incident light from the side surface of the chip due to unevenness of the subject and its surrounding luminance. Can not.
[0031]
[Means for Solving the Problems]
The invention of claim 1 is a light projecting means. so Without light projection, signal accumulation is performed for light from a subject received by a charge storage type sensor unit composed of a plurality of pixels, and subject distance or defocus amount is obtained based on the accumulated signal, Focusing and projecting means so When it is inappropriate to obtain the subject distance or defocus amount based on the accumulated signal without projecting, the projecting means so In a focusing device that performs signal accumulation on the light from the subject by the sensor unit in the projected state, obtains the subject distance or defocus amount based on the accumulated signal, and performs focusing. Photometric means provided separately from the sensor unit; The luminance information is obtained based on the accumulated signal accumulated in the sensor unit in a state where no light is projected by the light projecting means, and the luminance information and the Measurement When the difference from the luminance information from the light means is more than the predetermined value When performing signal accumulation in the charge accumulation type sensor unit, The light projecting means by Prohibit floodlight Control means for controlling Is.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0036]
FIG. 1 is a block diagram showing the configuration of a camera having a distance measuring device according to the present invention.
[0037]
In FIG.
Reference numeral 101 denotes a camera control unit (hereinafter referred to as CPU) that performs overall camera sequence control and includes an A / D conversion unit 105 and a memory 106, a distance calculation unit 107, a luminance calculation unit 108, and a luminance comparison unit 109, which will be described later.
[0038]
Reference numeral 102 denotes photometric means for detecting the luminance of the subject.
[0039]
Reference numeral 103 denotes a distance measuring apparatus that has the same configuration as that in FIG. 2 and detects and outputs an image signal from a subject by two sensor arrays 203 and 204.
[0040]
Reference numeral 105 denotes an A / D converter that digitizes an analog signal or the like corresponding to the image signal of the subject output from the distance measuring unit 103.
[0041]
A memory 106 stores information such as the image signal of the subject digitized by the A / D conversion unit 105.
[0042]
Reference numeral 107 denotes distance calculation means for calculating the distance to the subject by calculating the phase difference between the subject image signals detected by the two sensor arrays 203 and 204 in FIG.
[0043]
Reference numeral 108 denotes luminance calculation means for calculating the luminance of the subject from the image signal of the subject detected by the distance measuring means 103.
[0044]
Reference numeral 109 denotes a luminance comparison unit that compares the luminance of the subject detected by the photometry unit 102 with the luminance of the subject calculated by the luminance calculation unit 108 from the output information of the distance measurement unit 103.
[0045]
Here, if the difference between the luminance of the subject detected by the photometry unit 102 and the luminance of the subject calculated by the luminance calculation unit 108 is small, it is determined that the distance measurement unit 103 does not leak electric charges due to external light. On the other hand, when the luminance difference is large, it is determined that charges leak due to external light. When the electric charge leaks due to the external light, the luminance calculation means 108 corrects the luminance distribution of the subject detected by the distance measuring means 103 due to the leaked signal and the dark pixel level as shown in FIGS. The brightness cannot be calculated. Therefore, it is possible to make a difference from the luminance of the subject detected by the photometric means 102 that can correctly detect the luminance of the subject. From this difference, it is possible to detect leakage of electric charge due to external light in the distance measuring means 104.
[0046]
The photometry means 102 is a photoelectric conversion element such as an SPD, and is larger than the photoelectric conversion element of the distance measurement means 103 and can obtain a large number of signals from the subject, so that it is not easily affected by leakage of electric charges.
[0047]
110 is a warning display for displaying to the photographer that the distance measurement is impossible when the brightness comparison means 109 detects the brightness difference and the distance measurement means 102 determines that light leakage has occurred. Means.
[0048]
Reference numeral 111 denotes shutter driving means for controlling the opening of the shutter based on the detection result from the photometric means 102.
Reference numeral 112 denotes lens driving means for driving a photographing lens (not shown) based on the detection result of the distance to the subject calculated by the distance calculating means 107 and focusing the subject on the film surface.
[0049]
Reference numeral 113 denotes film supply means for performing autoloading, winding and rewinding of the film.
[0050]
114 is a switch SW1 that activates an electric circuit in the camera with a first stroke of a shutter button (not shown) to detect photometry and distance measurement,
Reference numeral 115 denotes a second stroke of a shutter button (not shown), which is SW2 serving as an activation signal for a shooting sequence after SW1.
[0051]
Next, the operation flow of the camera in this embodiment will be described with reference to the flowchart of FIG.
[0052]
[# 301]
First, in step 301, the CPU 101 detects whether or not SW1 (114), which is the first stroke of the release SW, is turned on, and waits until SW1 is turned on. When SW1 ON is detected, the process proceeds to the next step 302.
[0053]
[# 302]
In step 302, the photometric unit 102 performs photometry on the subject, and stores the photometric result (subject brightness) in the memory 106.
[0054]
[# 303]
Next, in step 303, the signal accumulation of all the pixels of the first and second sensor arrays 203 and 204 in the photometry means 103 is permitted by the RES pulse and the ST pulse, and the accumulation operation is started.
[0055]
[# 304]
In step 304, the PKMON signal level output from the peak detection unit 207 in the distance measuring means 103 is A / D converted by the A / D conversion unit 105 built in the CPU 101, and the level is checked for accumulation. It is determined whether the amount is at a predetermined level. In this embodiment, as the accumulation amount increases, the PKMON level increases. Therefore, if the PKMON level exceeds the predetermined level, it is determined that the accumulation amount has reached the predetermined level, and the process proceeds to the next step 306. Stops the accumulation operation.
[0056]
On the other hand, if the PKMON level is equal to or higher than the predetermined level, that is, if the accumulation level has not reached the predetermined level, it is determined that the accumulation level has not reached the predetermined level, and the process proceeds to step 305.
[0057]
[# 305]
In step 305, it is determined whether or not the time since the start of accumulation (hereinafter, accumulation time) has reached a preset maximum time. If the accumulation time has not reached the maximum time, the process proceeds to step 304 and the accumulation is continued. On the other hand, if the accumulation time has reached the maximum time, the process proceeds to step 306 and the accumulation operation is stopped.
[0058]
Here, the reason for determining whether or not the maximum time has been reached is that, for example, in photographing in a dark place or the like, the subject brightness is very low, so the accumulation level does not reach the predetermined level no matter how much time passes. Therefore, setting the maximum accumulation time prevents the distance measurement accumulation operation from being unnecessarily prolonged.
[0059]
[# 306]
In step 306, the accumulation operation in the first signal accumulation unit 205 and the second signal accumulation unit 206 in the distance measuring unit 103 is terminated by the ST pulse, and simultaneously the accumulation signal level of each pixel is held.
[0060]
[# 307]
In step 307, a signal read operation is started.
[0061]
First, the signals of the first sensor array 203 and the second sensor array 204 in the distance measuring means 103 are sequentially output to OUT by the read clocks CLK1 and CLK2 pulses.
[0062]
At this time, the CPU 101 performs A / D conversion by the A / D converter 105 in synchronization with the CLK1 pulse and the CLK2 pulse, and sequentially stores them at predetermined addresses in the memory 106.
[0063]
[# 308]
In step 308, the luminance calculation means 108 calculates the luminance of the subject from the image signal from the distance measurement means 103 stored in the memory 106 and the time required for accumulation. As a method of obtaining the luminance, for example, a method of calculating a value according to the luminance from the level and accumulation time of the signal indicating the peak as a signal among the signals from the read sensor array, or changing to the peak, A method of calculating a value corresponding to luminance using an average value of signals of each pixel (excluding dark pixels) or a signal level from a pixel at a predetermined position or range such as a central portion is used. Further, the luminance may be obtained from only the pixel signal without using the accumulation time.
[0064]
[# 309]
In step 309, the luminance comparison unit 109 determines whether or not the difference between the subject luminance (step 302) by the photometry unit 102 and the subject luminance by the distance measurement unit 103 calculated in step 308 is equal to or less than a predetermined level. .
[0065]
If the luminance difference is less than or equal to the predetermined level, the distance measuring means 103 determines that no leakage of charges due to external light has occurred, and proceeds to step 310.
On the other hand, if the luminance difference is greater than or equal to the predetermined level, it is determined that charge leakage has occurred in the pixels of the distance measuring means 103 due to strong external light, and the process proceeds to step 311.
[0066]
[# 310]
In step 310, the distance calculation means 107 calculates the distance to the subject from the phase difference between the image signals obtained by the sensor arrays 203 and 204 of the distance measurement means 103 stored in the memory 106, and the distance measurement. The result is stored in the memory 106.
[0067]
[# 311]
In step 311, it is determined that the difference between the subject luminance (step 302) obtained by the photometry unit 102 and the subject luminance data calculated by the distance measurement unit 103 calculated in step 307 is equal to or higher than a predetermined level. (Step 309) In this case, leakage of electric charges has occurred in the pixels of the distance measuring means 103 due to strong external light, and the distance to the subject cannot be detected correctly. Therefore, the result of the distance calculation means 107 is determined as the hyperfocal distance of the taking lens regardless of the detection result of the distance measurement means 103 and stored in the memory 106.
[0068]
[# 312]
In step 312, the warning display means 110 informs a photographer (not shown) that the distance measuring operation by the distance measuring means 103 is impossible.
[# 313]
In step 313, it is determined whether SW2 is ON. When it is determined that SW2 is not ON, the process returns to step 313, and when it is determined that SW2 is ON, the process proceeds to step 314.
[0069]
[# 314]
In step 321, the lens driving unit 112 controls driving of the photographing lens in accordance with the distance measurement result (step 310 and step 311) stored in the memory.
[0070]
[# 315]
In step 315, shutter drive control is performed by the shutter control means 111 in accordance with the photometric result (step 302) stored in the memory.
[0071]
[# 316]
In step 316, the film supply unit 113 controls film supply to the next photographing frame. This completes a series of camera sequences.
[0072]
As described above, it is possible to prevent erroneous distance measurement by determining the leakage of electric charge by the distance measuring means 103 from the difference in subject luminance obtained by the light measuring means 102 and the distance measuring means 103.
[0073]
(Second Embodiment)
A second embodiment according to the present invention will be described with reference to FIG.
[0074]
FIG. 7 is a block diagram showing the configuration of the camera in the present embodiment. Since the components having the same symbols as those in FIG. 1 have already been described, the description thereof is omitted here.
[0075]
In FIG.
Reference numeral 104 denotes auxiliary light illuminating means for projecting illumination light onto the subject when the accumulation amount of the signal from the subject is equal to or less than a predetermined level in the distance measuring means 103.
[0076]
Next, the operation flow of the camera in this embodiment will be described with reference to the flowchart of FIG.
[0077]
[# 501]
First, in step 501, the CPU 101 detects whether or not SW1 (114), which is the first stroke of the release SW, is turned on, and waits until SW1 is turned on. When SW1 ON is detected, the process proceeds to the next step 502.
[0078]
[# 502]
In step 502, the photometric unit 102 performs photometry on the subject, and stores the photometric result (subject luminance) in the memory 106.
[0079]
[# 503]
Next, in step 503, signal accumulation of all the pixels of the first and second sensor arrays 203 and 204 in the photometry means 103 is permitted by the RES pulse and ST pulse, and accumulation operation is started.
[0080]
[# 504]
In step 504, the PKMON signal level output from the peak detection unit 207 in the distance measuring means 103 is A / D converted by the A / D conversion unit 105 built in the CPU 101, and the level is checked for accumulation. It is determined whether the amount is at a predetermined level. In this embodiment, as the accumulation amount increases, the PKMON level increases. Therefore, if the PKMON level is equal to or lower than the predetermined level, it is determined that the accumulation amount has reached the predetermined level, and the process proceeds to the next step 506. Stops the accumulation operation.
[0081]
On the other hand, if the PKMON level is equal to or higher than the predetermined level, if the accumulated level has not reached the predetermined level, it is determined that the accumulated level has not reached the predetermined level, and the process proceeds to Step 305.
[0082]
[# 505]
In step 505, it is determined whether or not the time since the start of accumulation (hereinafter, accumulation time) has reached a preset maximum time. If the accumulation time has not reached the maximum time, the process proceeds to step 504 and the accumulation is continued. On the other hand, if the accumulation time has reached the maximum time, the process proceeds to step 506 and the accumulation operation is stopped.
[0083]
[# 506]
In step 506, the accumulation operation in the first signal accumulation unit 205 and the second signal accumulation unit 206 in the distance measuring means 103 is terminated by the ST pulse, and simultaneously the accumulated signal level of each pixel is held.
[0084]
[# 507]
In step 507, a signal read operation is started.
[0085]
First, the signals of the first sensor array 203 and the second sensor array 204 in the distance measuring means 103 are sequentially output to OUT by the read clocks CLK1 and CLK2 pulses.
[0086]
At this time, the CPU 101 performs A / D conversion by the A / D converter 105 in synchronization with the CLK1 pulse and the CLK2 pulse, and sequentially stores them at predetermined addresses in the memory 106.
[0087]
[# 508]
In step 508, the level of the PKMON signal after stopping accumulation is checked by the same operation as in step 504 to determine whether or not the accumulation amount in the distance measuring means 103 is equal to or higher than a predetermined level. If the PKMON level is greater than or equal to the predetermined amount, the accumulated amount has reached the predetermined level, so that the process proceeds to step 518 to calculate the distance to the subject.
[0088]
On the other hand, if the PKMON level is less than or equal to the predetermined amount, the accumulated amount has not reached the predetermined level, so it is determined that a distance measuring operation using the auxiliary light illumination means 104 is necessary, and the routine proceeds to step 509.
[0089]
[# 509]
In step 509, as in step 308 of the first embodiment, the luminance calculation means 108 determines the luminance of the subject from the image signal of the distance measuring means 103 stored in the memory 106 and the time required for accumulation. Is calculated.
[0090]
[# 510]
In step 510, the brightness comparison unit 109 determines whether or not the difference between the subject brightness by the photometry unit 102 (step 502) and the subject brightness by the distance measurement unit 103 calculated in step 509 is equal to or less than a predetermined level. .
[0091]
If the luminance difference is less than or equal to the predetermined level, the distance measuring means 103 determines that no leakage of charges due to external light has occurred, and proceeds to step 511.
[0092]
On the other hand, if the luminance difference is greater than or equal to the predetermined level, it is determined that charge leakage has occurred in the dark pixels of the distance measuring means 103 due to strong external light, and the process proceeds to step 519.
[0093]
[# 511]
In step 511, the auxiliary light illumination unit 104 is turned on, and the distance measuring unit 103 illuminates the subject so that a signal from the subject can be obtained more.
[0094]
[# 512]
In step 512, the accumulation operation by the distance measuring means 103 is started by the same operation as in step 503.
[0095]
[# 513]
In step 513, as in step 504, the PKMON level is compared with a predetermined level to determine whether or not the accumulated amount has reached an appropriate level. If the PKMON level is equal to or lower than the predetermined level, the process proceeds to step 515 to stop the accumulation operation. On the other hand, if the PKMON level is equal to or higher than the predetermined level, the process proceeds to step 514.
[0096]
[# 514]
In step 514, as in step 505, it is determined whether or not the accumulation time has reached a preset maximum time. If the accumulation time has not reached the maximum time, the process proceeds to step 513 to continue accumulation. On the other hand, if the accumulation time has reached the maximum time, the process proceeds to step 515 to stop the accumulation operation.
[0097]
Here, the maximum time of the accumulation operation by the auxiliary light irradiation is set longer than the maximum time of the accumulation operation without using the auxiliary light (step 505) so that more signals from the subject can be obtained.
[0098]
[# 515]
In step 515, the accumulation operation in the first signal accumulation unit 205 and the second signal accumulation unit 206 in the distance measuring unit 103 is stopped by the same operation as in step 506.
[0099]
[# 516]
In step 516, the auxiliary light illuminating means 104 is turned off, and the process proceeds to step 517.
[0100]
[# 517]
In step 517, the signals of the first sensor array 203 and the second sensor array 204 in the distance measuring means 103 are sequentially output to OUT by the same operation as in step 507, and the A / D converter 105 performs A / D conversion. The data are converted and sequentially stored at predetermined addresses in the memory 106.
[0101]
[# 518]
In step 518, the distance calculation means 107 calculates the distance to the subject from the phase difference between the image signals of the subjects obtained by the sensor arrays 203 and 204 of the distance measurement means 103 stored in the memory 106.
[0102]
[# 519]
In step 519, it is determined that the difference between the subject brightness (step 102) by the photometry unit 102 and the subject brightness by the distance measurement unit 103 calculated in step 307 is equal to or higher than a predetermined level. (Step 510) In this case, leakage of electric charges has occurred in the dark pixels of the distance measuring means 103 due to strong external light, and the distance to the subject cannot be detected correctly. Therefore, the result of the distance calculation means 107 is determined as the hyperfocal distance of the taking lens regardless of the detection result of the distance measurement means 103 and stored in the memory 106.
[0103]
[# 520]
In step 520, the warning display means 110 notifies the photographer (not shown) that the distance measuring operation by the distance measuring means 103 is impossible.
[0104]
[# 521]
In step 521, it is determined whether or not SW2 is ON. When it is determined that SW2 is not ON, the process returns to step 521, and when it is determined that SW2 is ON, the process proceeds to step 522.
[0105]
[# 522]
In step 522, the lens driving unit 111 is controlled to drive the photographing lens according to the distance measurement result (step 518 or step 519) stored in the memory 106.
[0106]
[# 523]
In step 523, shutter drive control by the shutter control means 110 is performed in accordance with the photometric result (step 502) stored in the memory 106.
[0107]
[# 524]
In step 524, film supply control to the next photographing frame is performed by the film supply means 112. This completes a series of camera sequences.
[0108]
When an image signal cannot be obtained due to charge leakage as shown in FIG. 9 (FIG. 9), a distance measuring operation using auxiliary light is normally performed. However, as described above, when charge leakage in the distance measuring means 103 is detected from the difference in subject brightness obtained by the light measuring means 102 and the distance measuring means 103, the distance measuring operation using the auxiliary light is prohibited. . That is, it is possible to shorten the time required for the distance measuring operation by the auxiliary light at the time of high luminance which is not necessary.
[0109]
In each of the embodiments described above, unnecessary charge accumulation judgment due to external light is a method using photometric luminance and sensor luminance. Other methods include pixel signals read out from the sensor in steps 307 and 507. It is determined whether the signal of the dark pixel is at a predetermined level (changed from the level when the outside light does not enter and is at a predetermined level), and the level of the dark pixel is at the predetermined level. Sometimes, it may be determined that unnecessary charges are accumulated, and the process may move to Steps 311 and 519.
[0110]
Although the distance measuring device is shown in the embodiment, the present invention may be applied to a focus detection device that obtains a defocus amount using a signal from a sensor.
[0111]
【The invention's effect】
As described above, in each invention, the leakage of electric charge can be determined and detected, so that processing using an inappropriate signal accumulation result (for example, distance measuring operation) can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a distance measuring device using a photoelectric conversion device.
FIG. 3 is a flowchart for explaining a distance measuring operation in the distance measuring apparatus according to the first embodiment of the present invention.
4 is a timing chart and an output waveform when an output signal is captured in the photoelectric conversion device of FIG. 2;
FIG. 5 is a flowchart for explaining a distance measuring operation in the distance measuring apparatus according to the second embodiment of the present invention;
6 is a diagram showing a luminance distribution on a sensor array in the photoelectric conversion device of FIG. 2. FIG.
FIG. 7 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.
8 is a timing chart and an output waveform at the time of capturing when charge leakage occurs in the photoelectric conversion device of FIG. 2;
9 is a timing chart and an output waveform at the time of capturing when charge leakage further occurs in the photoelectric conversion device of FIG. 2;
[Explanation of symbols]
101 Camera control unit (CPU)
102 Photometric means
103 Ranging means
105 A / D converter
106 memory
107 Distance calculation means
108 Luminance calculation means
109 Luminance comparison means

Claims (2)

The light from the subject received by the charge storage type sensor unit composed of a plurality of pixels is accumulated without being projected by the light projecting means , and the subject distance or defocus is based on the accumulated signal. determine the amount, and performs focusing, based on the accumulated signal at without projecting light when the object distance or the defocus amount that is inappropriate for obtaining in-projecting optical means, were projected in the light projecting means In a focusing apparatus that performs signal accumulation on the light from the subject in the state, obtains the subject distance or defocus amount based on the accumulated signal, and performs focusing
Photometric means provided separately from the sensor unit;
Together determine the brightness information based on the accumulated signal accumulated in the sensor portion in a state that is not projected light by the light emitting means, the difference between the luminance information from the light means measuring said the luminance information is equal to or higher than a predetermined value Control means for controlling to prohibit the light projection by the light projecting means when storing the signal in the charge storage type sensor unit when being separated
Focusing apparatus characterized by having a. It further has a plurality of pixels including pixels that are shielded from light,
Claims, characterized in that it comprises determining means for determining in a state in which the shielding accumulated signal levels with the pixels in the light state exceeds a predetermined level spaced from the first level before the start accumulation Item 2. The focusing device according to Item 1 .

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