JP3795723B2 - Automatic focusing device, digital camera, portable information input device and focusing position detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an automatic focusing device, a digital camera, and a portable information input device, and more specifically, an automatic focusing device, a digital camera, a portable information input device that detect an in-focus position with an external AF and a CCD-AF, andIn-focus position detection methodAbout.
[0002]
[Prior art]
  As an AF method for a conventional electronic still camera, a CCD-AF method for finding a focus peak by a luminance signal accumulated in the CCD while driving a CCD or a focus lens in the optical axis direction, or a triangulation type automatic focus adjustment mechanism Was used alone.
[0003]
[Problems to be solved by the invention]
  However, as shown in FIG. 12, the CCD-AF system is a system in which the CCD or focus lens is driven from infinity to the nearest position to find the peak of focus, so it takes time to detect the in-focus position. There is a problem that it takes. In order to solve the above-described problem, in the CCD-AF system, as shown in FIG. 13A, rough sampling is performed from infinity to the nearest position to detect the approximate focus position, and then FIG. As shown in b), a method of detecting the final in-focus position by performing fine sampling near the approximate in-focus position has been proposed. According to such a method, the detection time of the in-focus position can be slightly shortened, but it cannot be said to be sufficient.
[0004]
MaIn addition, the above-described triangulation method has a problem that a parallax shift in distance measurement on the close distance side is likely to occur, and performance on the telephoto side is low. further,The focus position detection means may be blocked due to an error such as the photographer blocking the focus position detection means with a finger, and it may be difficult to detect the focus position with high accuracy.
[0005]
  The present invention has been made in view of the above, and for various subjects.HighAutomatic focusing device, digital camera, portable information input device capable of detecting focus position accuratelyIn-focus position detection methodThe purpose is to provide.
[0006]
[Means for Solving the Problems]
  In order to solve the above-described problem, the invention according to claim 1 is configured to capture a subject image input through the lens system including a lens system including a focus lens system that forms a subject image at a predetermined position. An imaging means for outputting image data, a subject brightness detection means for detecting the brightness of a subject based on the output of the imaging means, and the imaging means are used to sample the contrast of the subject by moving the lens system. The first focus position detecting means for detecting the focus position and the photoelectric conversion means different from the imaging means are used to detect the distance to the subject and detect the focus position of the lens system. 2 in-focus position detecting means, a first in-focus position detection execution instructing member for instructing execution of the first in-focus position detecting means, and a light amount input to a photoelectric conversion means different from the imaging means. Light intensity Whether or not to operate the first focus position detection means based on the subject brightness detected by the subject brightness detection means when the exit means and the first focus position detection execution instruction member are operated. If it is determined that the first focus position detection unit is to be operated, and if it is determined that the light amount is insufficient from the light amount detection unit, the first focus position detection unit is The detected focus position is the final focus position.If it is determined by the light quantity detection means that the light quantity is not insufficient, based on the focus position detected by the second focus position detection means before the operation of the first focus position detection execution instructing member. And determining the movement start position of the lens when the first focus position detecting means moves the lens system.And a control means.
[0009]
  Claims2The invention according to claim1In the automatic focusing device described above, when the control unit determines that the light amount is not insufficient from the light amount detection unit, the control unit detects the focus position detected by the first focus position detection unit and the second focus position detection unit. The final focus position is determined from the focus position detected by the focus position detection means.
[0010]
  Claims3The invention according to claim 1 is directed to claim 1.Or 2In the automatic focusing device described in the above,Second focus positionThe detection means isBy detecting the distance to the subject multiple timesDetects subject movementIn this case, the first in-focus position detecting means is not executed, but the final in-focus position is detected, or the position of the moving subject is predicted and the first in-focus position is detected. Calculate the start position of the position detection meansTo do.
[0011]
  Claims4The invention according to claim 1 to claim 13The automatic focusing device according to any one of the above is applied. According to the invention, claims 1 to claim3The automatic focusing device according to any one of the above is applied to a digital camera.
[0012]
  Claims5The invention according to claim 1 to claim 13The automatic focusing device according to any one of the above is applied. According to the invention, claims 1 to claim3The automatic focusing device according to any one of the above is applied to a portable information input device.
[0013]
  Claims6According to the invention, in a focus position detection method for detecting a focus position with respect to a subject of a lens system including a focus lens system, a subject brightness detection step of detecting the brightness of the subject based on an output of the image pickup means, and the image pickup means A first focus position detecting step of detecting the focus position by moving the lens system by sampling the contrast of the subject using a photoelectric conversion means different from the imaging means, A second in-focus position detecting step for detecting the in-focus position of the lens system by detecting a distance to the lens system, a light amount detecting step for detecting a light amount input to a photoelectric conversion means different from the imaging means, When the first focus position detection execution instructing member for instructing execution of the first focus position detection step is operated, the first focus is based on the subject brightness detected by the subject brightness detection step. Determines whether to operate the 置検 out step, in a case where it is determined that operating the first focus position detection step, the light quantity detectionProcessIf it is determined that the amount of light is further insufficient, the in-focus position detected by the first in-focus position detection step is set as the final in-focus position.If it is determined by the light amount detection step that the light amount is not insufficient, based on the focus position detected by the second focus position detection step before the operation of the first focus position detection execution instruction member. And determining the movement start position of the lens when the first focus position detection step moves the lens system.And a control process.
[0015]
  Claims7The invention according to claim6Described inIn-focus position detection methodIn the control step, the light quantity detectionIn the processIf it is determined that the amount of light is not insufficient, the final focus is determined from the focus position detected by the first focus position detection step and the focus position detected by the second focus position detection step. Determine the focal position.
[0016]
  Claims8The invention according to claim6 or 7Described inIn-focus position detection methodIn the aboveSecond focus positionThe detection process isBy detecting the distance to the subject multiple timesDetects subject movementIn this case, the first in-focus position detection step is not executed, but the final in-focus position is detected, or the position of the moving subject is predicted to predict the first in-focus position. Calculate the start position of the position detection processTo do.
[0017]
  FIG. 1 is a block diagram of a digital camera to which an automatic focusing device according to the present invention is applied. In the figure, reference numeral 100 denotes a digital camera. The digital camera 100 includes a lens system 101, a mechanical mechanism 102 including an aperture / filter unit, a CCD 103, a CDS circuit 104, a variable gain amplifier (AGC amplifier) 105, an A / A D converter 106, IPP 107, DCT 108, coder 109, MCC 110, DRAM 111, PC card interface 112, CPU 121, display unit 122, operation unit 123, SG (control signal generation) unit 126, strobe device 127, battery 128, DC-DC A converter 129, an EEPROM 130, a focus driver 131, a pulse motor 132, a zoom driver 133, a pulse motor 134, a motor driver 135, and an external AF sensor 136 are provided. A detachable PC card 150 is connected via the PC card interface 112.
[0018]
  The lens unit includes a mechanical mechanism 102 including a lens system 101, an aperture / filter unit, and the like. A mechanical shutter of the mechanical mechanism 102 performs simultaneous exposure of two fields. The lens system 101 is composed of, for example, a varifocal lens, and includes a focus lens system 101a and a zoom lens system 101b.
[0019]
  The focus driver 131 drives the pulse motor 132 according to the control signal supplied from the CPU 121 to move the focus lens system 101a in the optical axis direction. The zoom driver 133 drives the pulse motor 134 according to the control signal supplied from the CPU 121 to move the zoom lens system 101b in the optical axis direction. Further, the motor driver 135 drives the mechanical mechanism 102 in accordance with a control signal supplied from the CPU 121, and sets, for example, an aperture value of the aperture.
[0020]
  A CCD (charge coupled device) 103 converts an image input via the lens unit into an electrical signal (analog image data). A CDS (correlated double sampling) circuit 104 is a circuit for reducing noise in the CCD type image pickup device.
[0021]
  In addition, the AGC amplifier 105 corrects the level of the signal that has been correlated and sampled by the CDS circuit 104. The gain of the AGC amplifier 105 is set by the CPU 121 when setting data (control voltage) is set in the AGC amplifier 105 via a D / A converter built in the CPU 121. Further, the A / D converter 106 converts analog image data from the CCD 103 input via the AGC amplifier 105 into digital image data. That is, the output signal of the CCD 103 is converted into a digital signal through the CDS circuit 104 and the AGC amplifier 105 and by the A / D converter 106 at an optimum sampling frequency (for example, an integer multiple of the subcarrier frequency of the NTSC signal). Is done.
[0022]
  Further, an IPP (Image Pre-Processor) 107, a DCT (Discrete Cosine Transform) 108, and a coder (Huffman Encoder / Decoder) 109, which are digital signal processing units, are provided for digital image data input from the A / D converter 106. Various processing, correction, and data processing for image compression / decompression are performed separately for color differences (Cb, Cr) and luminance (Y). The DCT 108 and the coder 109 perform, for example, orthogonal transformation / inverse orthogonal transformation, which is a JPEG-compliant image compression / decompression process, and Huffman coding / decoding, which is a JPEG-compliant image compression / decompression process.
[0023]
  Further, an MCC (Memory Card Controller) 110 temporarily stores the compressed image and records it on the PC card 150 or reads it from the PC card 150 via the PC card interface 112.
[0024]
  The CPU 121 uses the RAM as a work area according to a program stored in the ROM, and controls all operations inside the digital camera according to an operation from the operation unit 123 or an external operation operation such as a remote controller (not shown). Specifically, the CPU 121 controls an imaging operation, an automatic exposure (AE) operation, an automatic white balance (AWB) adjustment operation, an AF operation, and the like.
[0025]
  Camera power is input from a battery 128, such as NiCd, nickel metal hydride, or a lithium battery, to the DC-DC converter 129 and supplied into the digital camera.
[0026]
  The display unit 122 is implemented by an LCD, LED, EL, or the like, and displays captured digital image data, decompressed recorded image data, a setting screen, and the like. The operation unit 123 includes a release key for instructing shooting, buttons for function selection, and other various settings from the outside. The CPU 121 executes an AF operation or the like when the release key is pressed halfway and RL-1 is turned on, and performs a shooting operation when the release key is fully pressed and RL-2 is turned on. In the EEPROM 130, adjustment data and the like used when the CPU 121 controls the operation of the digital camera are written.
[0027]
  The above-described digital camera 100 (CPU 121) includes a recording mode in which image data obtained by imaging a subject is recorded on the PC card 150, a display mode in which image data recorded on the PC card 150 is displayed, and captured image data. Is provided directly on the display unit 122.
[0028]
  FIG. 2 is a diagram illustrating an example of a specific configuration of the IPP 107. As shown in FIG. 2, the IPP 107 includes a color separation unit 1071 that separates digital image data input from the A / D converter 106 into R, G, and B color components, and separated R, G, and B images. A signal interpolation unit 1072 that interpolates data, a pedestal adjustment unit 1073 that adjusts the black level of each of the R, G, and B image data, and a white balance adjustment unit 1074 that adjusts the white level of each of the R and B image data , A digital gain adjustment unit 1075 that corrects R, G, and B image data with a gain set by the CPU 121, a gamma conversion unit 1076 that performs γ conversion of the R, G, and B image data, and an RGB image A matrix unit 1077 for separating data into color difference signals (Cb, Cr) and luminance signals (Y), and a video signal based on the color difference signals (Cb, Cr) and luminance signals (Y). A video signal processing unit 1078 to be output to the display unit 122, and a.
[0029]
  Further, the IPP 107 passes through only a Y calculating unit 1079 that detects luminance data (Y) of image data after pedestal adjustment by the pedestal adjusting unit 1073, and a predetermined frequency component of the luminance data (Y) detected by the Y calculating unit 1079. The BPF 1080 to be output, the AF evaluation value circuit 1081 that outputs the integrated value of the luminance data (Y) that has passed through the BPF 1080 to the CPU 121 as an AF evaluation value, and the digital count value corresponding to the luminance data (Y) detected by the Y calculation unit 1079 AE evaluation value circuit 1082 that outputs to the CPU 121 as an AE evaluation value, a Y calculation unit 1083 that detects luminance data (Y) of each of the R, G, and B image data after adjustment by the white balance adjustment unit 1074, and Y The luminance data (Y) of each color detected by the calculation unit 1083 is counted, and the AWB of each color is counted. And AWB evaluation value circuit 1084 outputs the CPU 121 as a value, and a CPUI / F1085 is an interface with the CPU 121, and the DCTI / F1086 such an interface with the DCT108.
[0030]
  The external AF sensor 136 in FIG. 1 is composed of a passive distance measuring sensor, and is used to measure the distance of the subject. FIG. 3 is a diagram showing a schematic configuration of the external AF sensor. The external AF sensor 136 includes a lens 151, photosensor arrays 152a (left side) and 152b (right side), and an arithmetic circuit (not shown). The principle of distance measurement of the external AF sensor 136 will be described with reference to FIGS. In FIG. 3, the distance to the subject is d, the distance between the lens 151 and the photo sensor arrays 152a (left side) and 152b (right side) is f, and the width of light input to the photo sensor arrays 152a (left side) and 152b (right side). , X1 and X2, and the distance between the photosensor arrays 152a and 152b on which light is incident is B, the distance d from the front surface of the external AF sensor 136 to the subject is obtained by triangulation by d = B · f / It can be calculated by (X1 + X2). FIG. 4 shows the subject images of the left and right photosensor arrays, and the arithmetic circuit integrates the light amounts of the subject images of the respective photosensor arrays and calculates the deviation of the left and right sensor data, thereby calculating the subject distance d. Calculate and output to the CPU 121.
[0031]
  In this specification, the operation of detecting the in-focus position using the external AF sensor 136 is referred to as external AF, and the case of detecting the in-focus position using the CCD 103 is referred to as CCD-AF (internal AF). In the CCD-AF, the focus lens 101a is moved, the AF evaluation value indicating the contrast of the subject corresponding to the image signal output from the CCD 103 is sampled, and the hill-climbing servo system using the peak position of the AF evaluation value as the in-focus position. Is used. Performing AF using external AF and CCD-AF is called hybrid AF.
[0032]
  Next, operations related to AF of the digital camera having the above-described configuration will be described with reference to FIGS. 5 to 8 are flowcharts for explaining operations related to AF of the digital camera executed under the control of the CPU 121.
[0033]
  In FIG. 5, first, when the power is turned on (step S1), the CPU 121 determines whether or not it is the execution timing of the external AF (step S2). In step S4, if the external AF execution timing is reached, the external AF distance measurement processing is executed (step S3), and the external AF sensor 136 measures the distance to the subject. The process proceeds to S4.
[0034]
  In step S4, the CPU 121 determines whether or not the release key is pressed halfway and the RL-1 key is turned on. If RL-1 is not ON, the process returns to step S2, and ranging processing of external AF is performed at the execution timing of external AF until RL-1 is turned ON. On the other hand, if RL-1 is turned on in step S4, the CPU 121 acquires an AE evaluation value indicating the brightness of the subject via the IPP 107, and the brightness at which CCD-AF is possible based on the AE evaluation value. Is determined (step S5). Specifically, when the AE evaluation value is larger than a predetermined value (first reference value), it is determined that the brightness is possible for the CCD-AF, and the AE evaluation value is a predetermined value (first reference value). Value) or less, it is determined that CCD-AF is not bright enough. If it is determined that the CCD-AF has sufficient brightness, the process proceeds to step S6.
[0035]
  On the other hand, if it is determined in step S5 that the CCD-AF is not bright enough, the process proceeds to step S31 in FIG. 6, and the CPU 121 does not execute the CCD-AF, but only the external AF is in focus. The final in-focus position is determined based on (Steps S31 to S33). Specifically, in step S31, external AF distance measurement processing is executed. In this external AF distance measurement process, the external AF sensor 136 measures the distance to the subject and detects the in-focus position. Then, the CPU 121 determines whether or not the external AF has ended (step S32). If the external AF has ended, the CPU 121 proceeds to step S33 to determine whether or not an appropriate external AF measurement result has been obtained. . Specifically, when the CPU 121 determines that the subject is darker than a predetermined value (second reference value) or has a low contrast based on the amount of light input to the external AF sensor 136, the external AF Is determined to be inappropriate. If it is determined that an appropriate measurement result has been obtained, the process proceeds to step S19 in FIG. 8, and the focus position detected by the external AF is determined as the final focus position. On the other hand, if it is determined in step S33 that an appropriate external AF measurement result has not been obtained, the process proceeds to step S21 in FIG. 8 to determine the normal focus position as the final focus position.
[0036]
  In step S6, the CPU 121 determines whether or not the result of the external AF is appropriate. Specifically, when the CPU 121 determines that the subject is darker than a predetermined value (second reference value) or has a low contrast based on the amount of light input to the external AF sensor 136, the external AF Is determined to be inappropriate. If it is determined that the result of the external AF is appropriate, the process proceeds to step S7.
[0037]
  On the other hand, if it is determined in step S6 that the result of the external AF is not appropriate, the process proceeds to step S41 in FIG. 7, and the CPU 121 determines the final focus position based on the focus result of only the CCD-AF. Is determined (steps S41 to S44). Specifically, in step S41, in order to sample the AF evaluation value in the entire movable area of the focus lens 101a, the CPU 121 performs CCD-AF when sampling the AF evaluation value in the entire area of the focus lens 101a. The position is moved to the start position (reference position), and CCD-AF is started for all areas (step S42). In the CCD-AF, the focus lens system 101a is moved from the start position, AF evaluation values are acquired in all areas, and the focus position is detected. Then, the CPU 121 determines whether or not the CCD-AF has ended (step S43). If the CCD-AF has ended, the CPU 121 proceeds to step S44, and whether an appropriate CCD-AF detection result has been obtained. Judge whether or not. Here, an appropriate detection result means a case where the AF evaluation value has a peak or the like, and an inappropriate detection result means a case where the AF evaluation value has no peak and the subject has no contrast. If it is determined that an appropriate detection result has been obtained, the process proceeds to step S20 in FIG. 8, and the focus position detected by the CCD-AF is determined as the final focus position. On the other hand, if it is determined in step S44 that a proper external AF detection result has not been obtained, the process proceeds to step S21 in FIG. 8 to determine the normal focus position as the final focus position.
[0038]
  If it is determined in step S5 in FIG. 5 that the CCD-AF is bright enough, and if it is determined in step S6 in FIG. 5 that the result of external AF is appropriate, the CPU 121 The in-focus position is detected by executing CCD-AF and external AF substantially simultaneously. Specifically, first, in step S7 in FIG. 5, the CPU 121 calculates the start position (reference position) of the CCD-AF based on the distance measurement result of the external AF in step S3, and calculates the calculated CCD-AF. The focus lens system 101a is moved to the start position (reference position). Subsequently, after moving the focus lens system 101a to the reference position, the CPU 121 starts the external AF and the CCD-AF substantially simultaneously (step S8). In the external AF, the external AF sensor 136 measures the distance to the subject and detects the focus position. In the CCD-AF, the focus lens system 101a is moved in the vicinity of the reference position, the AF evaluation value is acquired, and the focus position is detected.
[0039]
  Thereafter, the CPU 121 determines whether or not the external AF has ended (step S9). If the external AF has ended, the CPU 121 determines whether or not the result of the external AF is appropriate (step S10). Specifically, when the CPU 121 determines that the subject is darker than a predetermined value (second reference value) or has a low contrast based on the amount of light input to the external AF sensor 136, the external AF Is determined to be inappropriate. If it is determined that the result of the external AF is appropriate, the process proceeds to step S11. On the other hand, if it is determined that the result of the external AF is not appropriate, the process proceeds to step S41 in FIG. 7, and the CPU 121 executes CCD-AF over the entire area and based on the focus result of only the CCD-AF. Determine the final in-focus position.
[0040]
  In step S11, the CPU 121 determines whether there is a change in the distance measurement result of the external AF. Specifically, it is determined whether there is a change between the subject distance detected in step S3 and the subject distance detected in step S8. Here, a change indicates that the subject is moving. If it is determined that there is no change in the distance measurement result of the external AF, the process proceeds to step S14. On the other hand, when the CPU 121 determines that there is a change in the distance measurement result of the external AF, the CPU 121 interrupts the CCD-AF and based on the subject distance detected in step S3 and the subject distance detected in step S8. The position of the moving subject is predicted, a new start position (reference position) of the CCD-AF is calculated, and the focus lens system 101a is moved to the calculated start position (step S12). Then, the CCD-AF is re-executed near the new start position (step S13).
[0041]
  In step S14, the CPU 121 determines whether or not the CCD-AF has ended. If the CCD-AF has ended, the CPU 121 proceeds to step S15 in FIG. 8, and an appropriate CCD-AF detection result is obtained. It is determined whether or not. Here, an appropriate detection result means a case where the AF evaluation value has a peak or the like, and an inappropriate detection result means a case where the AF evaluation value has no peak and the subject has no contrast. If it is determined that an appropriate CCD-AF result has not been obtained, the process proceeds to step S19, and the focus position detected by the external AF is determined as the final focus position. On the other hand, if it is determined in step S15 that a proper CCD-AF detection result has been obtained, the process proceeds to step S16, where the CPU 121 determines the subject distance corresponding to the in-focus position detected by the CCD-AF and the external distance. It is determined whether or not the difference in subject distance detected by AF is within a predetermined range. As a result of the determination, if the difference between the subject distance corresponding to the in-focus position detected by the CCD-AF and the subject distance detected by the external AF is not within the predetermined range, the process proceeds to step S21 and the normal focus is performed. The position is determined as the final focus position.
[0042]
  On the other hand, if it is determined in step S16 that the difference between the subject distance corresponding to the in-focus position detected by the CCD-AF and the subject distance detected by the external AF is within a predetermined range, the process proceeds to step S17. The CPU 121 determines whether or not there is a high-luminance subject based on the sampling result of the AF evaluation value of the CCD-AF (the state of the contrast of the subject). When the CPU 121 determines that there is a high-luminance subject (step S18), the CPU 121 proceeds to step S19 and determines the focus position detected by the external AF as the final focus position. If it is determined in step S18 that there is no high-luminance subject, the focus position detected by the CCD-AF is determined as the final focus position (step S20).
[0043]
  Thereafter, the CPU 121 moves the focus lens system 101a to the determined focus position. When the release key is fully pressed and RL-2 is turned on, a shooting operation is performed, and the image data of the subject is captured and recorded in the PC card 150.
[0044]
  9 and 10 are timing charts for explaining the execution timing of the external AF and the CCD-AF. As shown in FIG. 9, the distance measurement process using external AF is executed prior to turning on RL-1, and when RL-1 is turned on, external AF and CCD-AF are executed substantially simultaneously.
[0045]
  FIG. 10 is a timing chart for explaining a case where execution of CCD-AF is interrupted and re-executed. If there is a change in the distance measurement result of the external AF (step S11 above), the currently executed CCD-AF (1) is interrupted, and the start position (reference position) of the CCD-AF is recalculated. Then, the focus lens system 101a is moved to the calculated start position (step S12), and CCD-AF (2) is re-executed from the recalculated start position (step S13).
[0046]
  FIG. 11 is an explanatory diagram for explaining a basic operation regarding the hybrid AF. In the figure, the vertical axis represents the contrast (AF evaluation value), and the horizontal axis represents the lens position (nearest to infinite). First, an in-focus position is detected by external AF, and then a fine sampling is performed by CCD-AF in the vicinity of the detected in-focus position to detect the in-focus position. Then, the final focusing position is determined based on both focusing positions.
[0047]
  As described above, in the present embodiment, when it is determined that the brightness of the subject is not at a level where CCD-AF can be performed, external AF is preferentially performed without performing CCD-AF. To determine the in-focus position.HighAn accurate in-focus position can be detected.
[0048]
  Further, in the present embodiment, when the brightness of the subject is at a level at which CCD-AF can be performed, if it is determined that the detection result of the external AF is not appropriate, the CCD-AF is preferentially applied to the entire area. Therefore, even when something is blocking the external AF sensor 136, it is possible to accurately detect the focus position. In other words, even if the photographer makes a mistake such as closing the external AF sensor 136 with a finger, the focus position can be detected with high accuracy.
[0049]
  In addition, since CCD-AF takes time, a moving subject is relatively weak. Therefore, the movement of the subject is detected based on the distance measurement results of the external AF ranging process performed at predetermined time intervals in step S3, and if there is a movement of the subject, the CCD-AF is executed. Instead, the focus position may be determined by preferentially executing external AF. Thereby, it is possible to detect the in-focus position with high accuracy even for a moving subject.
[0050]
  In the present embodiment, when the power is turned on, the distance measurement process is performed with the external AF at a predetermined interval even before the release key is pressed, that is, even when the release key is not pressed. When the release key is pressed, the reference position for the CCD-AF is calculated based on the distance measurement result of the external AF, and the CCD-AF is performed in the vicinity of the reference position. The AF time can be shortened as compared with the case where external AF is executed after the key is pressed and then CCD-AF is executed based on the result of the external AF.
[0051]
  In the present embodiment, since a passive distance measuring sensor is used as the external AF sensor, it is possible to reduce the size, reduce the cost, and simplify the processing.
[0052]
  Note that the present invention is not limited to the above-described embodiment, and can be appropriately modified and executed without changing the gist of the invention. For example, in the present embodiment, an example in which the automatic focusing device according to the present invention is applied to a digital camera has been described. However, the present invention is not limited to this, and the present invention is also applied to a portable information input device such as a PDA. Applicable. In short, the present invention can be applied to all apparatuses that perform AF when inputting an image.
[0053]
【The invention's effect】
  According to the automatic focusing device of the first aspect, the lens system forms a subject image at a predetermined position, and the imaging unit images the subject image input through the lens system and outputs image data. The luminance detection means detects the luminance of the subject based on the output of the imaging means, and the first focus position detection means uses the imaging means to move the lens system and sample the contrast of the subject to focus the focus position. The second focus position detection means uses a photoelectric conversion means different from the imaging means to detect the distance to the subject to detect the focus position of the lens system, and the control means When the focus position detection execution instructing member is operated, based on the subject brightness detected by the subject brightness detection means, it is determined whether to operate the first focus position detection means, and the first focus position detection means is determined. It is determined that the in-focus position detection means is operated. A case, if it is determined that the light quantity is insufficient from the light quantity detecting means, and the final in-focus position focus position where the first focus position detecting means detectsIf the light amount detection means determines that the light amount is not insufficient, the second focus position detection means detects the first focus position detection execution instruction member before operating the first focus position detection execution member. Determines the lens movement start position when the in-focus position detection means moves the lens system.Therefore, it is possible to detect the in-focus position with high accuracy for various subjects. Even when something is blocking the second focus position detection means, it is possible to accurately detect the focus position. In other words, even if the photographer makes a mistake such as blocking the second focus position detection means with a finger, the focus position can be detected with high accuracy.Furthermore, since the first focus position detection means is performed based on the focus position detected by the second focus position detection means prior to the operation of the first focus position detection execution instruction member, After the operation of the first focus position detection execution instructing member, the second focus position detection means is executed, and thereafter the first focus position detection means is executed based on the result of the second focus position detection means. Compared to the case, the time can be shortened.
[0054]
  Claims3According to the automatic focusing device according to claim 1,Or 2In the automatic focusing device according toSecond focus positionThe detection means isBy detecting the distance to the subject multiple timesDetects subject movementIn such a case, the first focus position detection means is not executed, but the final focus position is detected, or the position of the moving subject is predicted and the first focus position detection is performed. Calculate the starting position of the meansTherefore, in addition to the effect of the automatic focusing device according to the first aspect, it is possible to detect the in-focus position with high accuracy even for a moving subject.
[0055]
  Claims4According to the digital camera according to claim 1, claims 1 to3Since the automatic focusing device according to any one of the above is applied, it is possible to provide a digital camera capable of detecting a focusing position with high accuracy for various subjects. Play.
[0056]
  Claims5According to the portable information input device according to claim 1, claims 1 to3Since the automatic focusing device according to any one of the above is applied, it is possible to provide a portable information input device capable of detecting a focusing position with high accuracy for various subjects. There is an effect.
[0057]
  Claims6TakeIn-focus position detection methodThe lens system forms a subject image at a predetermined position, the imaging unit images the subject image input via the lens system and outputs image data, and the subject luminance detection step is performed by the output of the imaging unit. Based on this, the brightness of the subject is detected, and the first focus position detection step uses the imaging means to move the lens system, sample the contrast of the subject, detect the focus position, and detect the second focus. The position detection step uses a photoelectric conversion means different from the imaging means to detect the distance to the subject and detect the focus position of the lens system, and the control step is operated by the first focus position detection execution instructing member. If it is determined, based on the subject brightness detected by the subject brightness detection step, it is determined whether or not to operate the first focus position detection step, and the first focus position detection step is operated. If it is determined, the light amount detection If it is determined that the amount of the step is insufficient, and the final in-focus position focus position where the first focus position detection step has detectedIf it is determined by the light amount detection step that the light amount is not insufficient, based on the focus position detected by the second focus position detection step before the operation of the first focus position detection execution instruction member. And determining the movement start position of the lens when the first focus position detection step moves the lens system.Therefore, it is possible to detect the in-focus position with high accuracy for various subjects. Even when something is blocking the second focus position detection means, it is possible to accurately detect the focus position. In other words, even if the photographer makes a mistake such as blocking the second focus position detection means with a finger, the focus position can be detected with high accuracy.Further, since the first focus position detection step is performed based on the focus position detected by the second focus position detection step prior to the operation of the first focus position detection execution instructing member, After the operation of the in-focus position detection execution instructing member, the second focus position detection process is executed, and then the first focus position detection process is executed based on the result of the second focus position detection process. Compared to the case, the time can be shortened.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a digital camera according to an embodiment.
FIG. 2 is a diagram illustrating an example of a specific configuration of the IPP in FIG.
3 is a diagram showing a schematic configuration of the external AF sensor of FIG. 1. FIG.
FIG. 4 is an explanatory diagram for explaining a distance measuring principle of an external AF sensor.
FIG. 5 is a flowchart for explaining an operation related to AF (part 1);
FIG. 6 is a flowchart for explaining an operation related to AF (part 2);
FIG. 7 is a flowchart for explaining an operation related to AF (part 3);
FIG. 8 is a flowchart for explaining an operation related to AF (part 4);
FIG. 9 is a timing chart for explaining the execution timing of external AF and CCD-AF (part 1);
FIG. 10 is a timing chart for explaining the execution timing of external AF and CCD-AF (part 2);
FIG. 11 is an explanatory diagram for explaining a basic operation of the hybrid AF.
FIG. 12 is an explanatory diagram for explaining a conventional CCD-AF system.
FIG. 13 is an explanatory diagram for explaining a conventional CCD-AF system.
[Explanation of symbols]
  100 digital camera
  101 Lens system
  101a Focus lens system
  101b Zoom lens system
  102 Mechanical mechanism including autofocus
  103 CCD (Charge Coupled Device)
  104 CDS (correlated double sampling) circuit
  105 Variable Gain Amplifier (AGC Amplifier)
  106 A / D converter
  107 IPP (Image Pre-Processor)
  108 DCT (Discrete Cosine Transform)
  109 Coder (Huffman Encoder / Decoder)
  110 MCC (Memory Card Controller)
  111 RAM (internal memory)
  112 PC card interface
  121 CPU
  122 Display section
  123 Operation unit
  125 motor driver
  126 SG Department
  127 Strobe
  128 battery
  129 DC-DC converter
  130 EEPROM
  131 Focus driver
  132 Pulse motor
  133 Zoom driver
  134 Pulse motor
  135 Motor driver
  136 External AF sensor
  150 PC card
  151 lens
  152 Photosensor Array
  153 arithmetic circuit
  1071 Color separation unit
  1072 Signal interpolation unit
  1073 Pedestal adjustment unit
  1074 White balance adjustment section
  1075 Digital gain adjustment unit
  1076 γ converter
  1077 Matrix part
  1078 Video signal processor
  1079 Y operation part
  1080 BPF
  1081 AF evaluation value circuit
  1082 AE evaluation value circuit
  1083 Y operation part
  1084 AWB evaluation value circuit
  1085 CPU I / F
  1086 DCTI / F
  1075r, 1075g, 1075b multiplier

Claims (8)

A lens system including a focus lens system that forms a subject image at a predetermined position;
Imaging means for imaging a subject image input via the lens system and outputting image data;
Subject brightness detection means for detecting the brightness of the subject based on the output of the imaging means;
A first in-focus position detecting unit that detects the in-focus position by sampling the contrast of the subject by moving the lens system using the imaging unit;
Second focus position detection means for detecting a focus position of the lens system by detecting a distance to a subject using a photoelectric conversion means different from the imaging means;
A first focus position detection execution instructing member for instructing execution of the first focus position detection means;
A light amount detection means for detecting a light amount input to a photoelectric conversion means different from the imaging means;
When the first focus position detection execution instructing member is operated, based on the subject brightness detected by the subject brightness detection means, it is determined whether or not to operate the first focus position detection means;
Even if it is determined that operating the first focus position detecting means, if a more amount of light on the light quantity detecting means is determined to be insufficient, the first focus position detecting means detects Let the focus position be the final focus position ,
When it is determined by the light quantity detection means that the light quantity is not insufficient, based on the focus position detected by the second focus position detection means before the operation of the first focus position detection execution instruction member, Control means for determining a movement start position of the lens when the first focus position detection means moves the lens system ;
An automatic focusing device characterized by comprising: When it is determined that the light amount is not insufficient from the light amount detection unit, the control unit detects the focus position detected by the first focus position detection unit and the second focus position detection unit. from the in-focus position, an automatic focusing device according to claim 1, characterized in that to determine the final focus position. The second in-focus position detecting means does not execute the first in-focus position detecting means when the movement of the object is detected by detecting the distance to the object a plurality of times , and finally The automatic position according to claim 1 or 2 , wherein a focus position is detected or a start position of the first focus position detection means is calculated by predicting a position of a moving subject. Focusing device. A digital camera to which the automatic focusing device according to any one of claims 1 to 3 is applied. A portable information input device to which the automatic focusing device according to any one of claims 1 to 3 is applied. In a focus position detection method for detecting a focus position with respect to a subject of a lens system including a focus lens system,
A subject brightness detection step for detecting the brightness of the subject based on the output of the imaging means;
A first in-focus position detecting step of detecting the in-focus position by sampling the contrast of the subject by moving the lens system using the imaging means;
A second focus position detecting step of detecting a focus position of the lens system by detecting a distance to a subject using a photoelectric conversion means different from the imaging means;
A light amount detection step of detecting a light amount input to a photoelectric conversion means different from the imaging means;
When the first focus position detection execution instructing member for instructing execution of the first focus position detection step is operated, the first focus position is based on the subject brightness detected by the subject brightness detection step. Determine whether to activate the detection process,
Even if it is determined that operating the first focus position detection step, if a more amount of light on the light quantity detecting step is determined to be insufficient, the first focus position detection step has detected Let the focus position be the final focus position ,
Wherein if it is determined that the light amount is not insufficient by the amount of light detecting step, based on the second focus position detection process focus detected position before operation of the first focus position detection execution instruction member A control step of determining a movement start position of the lens when the first focus position detection step moves the lens system ;
In-focus position detection method characterized by including. Wherein the control step, if a more amount of light on the light quantity detecting step is determined not to be missing, the first focus position detection process and the focus position detecting the second focus position detection step detects The in- focus position detection method according to claim 6 , wherein a final in-focus position is determined from the in- focus position . In the second focus position detection step, when the movement of the subject is detected by detecting the distance to the subject a plurality of times , the final focus position detection step is not performed and the final focus position detection step is performed. a detecting a focus position, or, according to claim 6 or 7, characterized in that to predict the location of an object that is moving for calculating a start position of the first focus position detection step In-focus position detection method .

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