JP2005316187A - Focusing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focusing apparatus capable of accurately compensating temperature, and capable of highly accurately focusing. <P>SOLUTION: Regarding the focusing apparatus, an object image transmitted through a photographing lens is divided into two images, and a distance between the two images is measured, and the deviation from the distance between the two images at focusing is obtained, and then, the defocusing quantity of the photographing lens is obtained, and the focusing apparatus is provided with a focus detecting element 1 having a plurality of photoelectric conversion elements, a temperature detecting means 2 arranged on the same IC chip on which the focusing detecting element 1 is arranged, a correcting means 3 for correcting the defocusing quantity detected by the focus detecting means 5, a time counting means 4 for counting an elapsed time after the power is supplied to the focus detecting element 1, and the focus detecting means 5 for detecting the focus based on the output of the focus detecting element 1, and detecting the defocusing quantity, and the defocusing quantity is corrected by the correcting means 3 based on the output of the temperature detecting means 2 obtained when the output of the time counting means 4 is lower than a prescribed value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a focus adjusting apparatus that obtains a defocus amount of the photographing lens from a shift amount of two images at the time of focusing.

  The focus adjustment apparatus disclosed in Patent Document 1 is a known TTL phase difference detection method, that is, a subject image that has passed through a photographing lens is divided into two images, and the interval between the two images is measured. The present invention relates to a focus adjustment apparatus that employs a method of calculating a defocus amount of the photographic lens by obtaining an interval shift amount.

  In this focus adjustment apparatus, the following method is used to prevent a decrease in AF accuracy due to temperature characteristics of an AF (autofocus) optical system for detecting a TTL phase difference. That is, a temperature detection circuit is formed on the same IC chip as the AF sensor, the temperature is detected by this temperature detection circuit and adopted as the environmental temperature, and the temperature characteristic of the TTL phase difference type AF optical system is corrected.

The focus adjustment device disclosed in Patent Document 2 is a focus adjustment device that adopts a TTL phase difference detection method as in Patent Document 1, and includes a temperature detection element separately from the AF sensor. The temperature characteristic of the AF optical system is corrected based on the detected temperature.
Patent Document 1 is Japanese Patent Publication No. 2595634. Patent Document 2 is Japanese Patent Publication No. Heisei 8-33511.

  The focus adjustment device of Patent Document 1 has the following problems. That is, when the AF sensor is operated, power is consumed inside the AF sensor, so that the AF sensor IC chip temperature itself rises, resulting in a temperature detection result deviating from the desired environmental temperature. For this reason, there is a problem that the accuracy of temperature correction is lowered, and eventually AF accuracy is lowered and the focus is shifted. In addition, since temperature detection data is read with the same serial output as a series of analog outputs when reading sensor data, there is a possibility that temperature detection results will vary repeatedly, resulting in reduced temperature correction accuracy and reduced AF accuracy. It was.

  The focus adjustment apparatus of Patent Document 2 can accurately measure the environmental temperature, but there is a problem in that it is necessary to provide a separate temperature detection element, resulting in an increase in cost.

  The present invention has been made to solve the above-described problem, and provides a focus adjustment device that can perform accurate temperature correction and perform high-precision focus adjustment without incurring a cost increase. The purpose is to provide.

  The focus adjusting apparatus according to claim 1 of the present invention divides the subject image that has passed through the taking lens into two images, measures the interval between the two images, and obtains the amount of deviation from the interval between the two images at the time of focusing. In the focus adjustment device for obtaining the defocus amount of the photographing lens, a focus detection element having a plurality of photoelectric conversion elements for forming the two images, and a temperature detection provided on the same IC chip as the focus detection element Means, a correction means for correcting the defocus amount detected according to the output of the temperature detection means, and a time measurement means for measuring the time since the focus detection element is powered on, The correcting means corrects the defocus amount based on the output of the temperature detecting means when the output of the time measuring means is smaller than a predetermined value.

  The focus adjustment apparatus according to claim 2 of the present invention divides the subject image that has passed through the taking lens into two images, measures the interval between the two images, and obtains the amount of deviation from the interval between the two images at the time of focusing. In the focus adjustment device for obtaining the defocus amount of the photographing lens, a focus detection element having a plurality of photoelectric conversion elements for forming the two images, and a temperature detection provided on the same IC chip as the focus detection element Means, correction means for correcting the defocus amount detected according to the output of the temperature detection means, and control means for causing the focus detection element to repeatedly perform a focus detection operation and to repeatedly perform temperature detection. The correction means performs correction after statistically processing the output of the temperature detection means repeatedly detected.

  According to a third aspect of the present invention, the focus adjustment apparatus divides the subject image that has passed through the taking lens into two images, measures the interval between the two images, and obtains the amount of deviation from the interval between the two images at the time of focusing. In the focus adjustment device for obtaining the defocus amount of the photographing lens, a focus detection element having a plurality of photoelectric conversion elements for forming the two images, and a temperature detection provided on the same IC chip as the focus detection element A correction means for correcting a defocus amount detected in accordance with an output of the temperature detection means, a time measurement means for measuring the time since the focus detection element is powered on, and the focus detection element Control means for repeatedly performing the focus detection operation and repeatedly performing temperature detection, and the correction means outputs the temperature detection means when the output of the time measurement means is smaller than a predetermined value. For it, it corrects the defocus amount based on an output of the temperature detecting means repeatedly detects the statistical processing result.

  According to the present invention, it is possible to provide a focus adjustment device capable of performing accurate temperature correction and performing high-precision focus adjustment without causing an increase in cost.

Prior to the description of the embodiment of the present invention, the concept of the present invention will be described.
FIG. 1 is a block diagram showing one concept of the focus adjusting apparatus of the present invention.
The focus adjustment device 7A divides the subject image that has passed through the photographing lens into two images, measures the distance between the two images, obtains the amount of deviation from the distance between the two images at the time of focusing, and defocuses the photographing lens. A focus adjustment device for determining the amount. The apparatus 7A includes a focus detection element 1 having a plurality of photoelectric conversion elements for forming two images, and a temperature detection unit that is provided on the same IC chip as the focus detection element 1 and generates an output related to temperature. 2, a correction unit 3 that corrects the defocus amount detected by the focus detection unit 5 according to the output of the temperature detection unit 2, and a time measurement unit 4 that measures the time after the focus detection element 1 is powered on. And a focus detection means 5 for detecting the focus based on the output of the focus detection element 1 and detecting the defocus amount. When the output of the time measurement means 4 is smaller than a predetermined value by the correction means 3 The defocus amount is corrected based on the output of the temperature detecting means 2.

FIG. 2 is a block diagram showing another concept of the focus adjustment apparatus of the present invention.
The focus adjusting device 7B also divides the subject image that has passed through the taking lens into two images, measures the interval between the two images, finds the amount of deviation from the interval between the two images at the time of focusing, and determines the defocus amount of the taking lens. It is the focus adjustment device for which The apparatus 7B includes a focus detection element 1 having a plurality of photoelectric conversion elements for forming two images, and a temperature detection unit that is provided on the same IC chip as the focus detection element 1 and generates an output related to temperature. 2, a correction unit 3 that corrects the defocus amount detected by the focus detection unit 5 according to the output of the temperature detection unit 2, and a focus that detects the defocus amount by performing focus detection based on the output of the focus detection element 1. The correction unit 3 includes a detection unit 5 and a control unit 6 that causes the focus detection element 1 to repeatedly perform a focus detection operation and cause the temperature detection unit 2 to repeatedly perform temperature detection. The control means 6 is controlled so as to execute the correction after statistically processing the output of the temperature detection means 2 that has been performed.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a cross-sectional view showing the main configuration of the interchangeable lens camera equipped with the focus adjustment apparatus of the first embodiment of the present invention. FIG. 4 is a diagram showing a detailed configuration of a focus detection optical system for guiding subject light to the photoelectric conversion element array in the focus adjustment apparatus and its optical path. FIG. 5 is a diagram showing a focus detection area (area) in the shooting screen of the camera. FIG. 6 is a block diagram of the camera body side electric control circuit of the camera. FIG. 7 is a block diagram of the interchangeable lens side electric control circuit of the camera. FIG. 8 is a block diagram of an AF sensor in the camera body side electric control circuit. FIG. 9 is a circuit diagram of a temperature detection unit in the AF sensor. FIG. 10 is a diagram illustrating an example of output characteristics in the temperature detection unit.

  The camera 100 of the present embodiment is an interchangeable lens camera (single-lens reflex camera), and includes an interchangeable lens 11 and a camera body 10 as shown in FIG.

  The camera body 10 mainly includes a main mirror 14 having a sub mirror 17, a finder 16 having a pentaprism 15, a shutter 28, an image sensor 29, and a focus detection disposed at the lower part of the camera body. The apparatus 12 includes the camera body side electric control circuit shown in FIG.

  The interchangeable lens 11 is detachable from the camera body 10, and includes an imaging lens 13, which includes a focus lens 13A and a zoom lens 13B, an aperture 18, a zoom ring 26, and an interchangeable lens side electric control circuit shown in FIG. Etc.

  Note that the focus adjustment apparatus of the present embodiment divides the subject image that has passed through the taking lens into two images, measures the interval between the two images, and obtains the deviation amount from the interval between the two images at the time of focusing. An apparatus for obtaining a defocus amount of a lens, which includes the focus detection device 12 having an AF sensor, the camera body side electric control circuit incorporating the controller, the interchangeable lens side electric control circuit, and the like.

  In the camera body 10 to which the interchangeable lens 11 is attached, in the finder observation state, a part of the light beam from the subject that has passed through the photographing lens 13 is reflected by the main mirror 14 and the other part is transmitted. The light beam reflected by the main mirror 14 is guided to the eyepiece of the finder 16 through the pentaprism 15. On the other hand, the light beam transmitted through the main mirror 14 is reflected by the sub mirror 17 and guided to the focus detection device 12. At the time of photographing, the main mirror 14 and the sub mirror 17 are retracted from the optical path of the optical axis O (photographing lens) by operating a release switch (not shown) (in the direction of the arrow in FIG. 3), and the shutter 28 is opened, thereby The photographing light beam is guided to perform exposure.

  The focus detection device 12 is focus detection means that adopts a TTL phase difference detection method, and as shown in FIG. 3, a field mask 19 that narrows the light beam that has passed through the photographing lens 13 and an infrared cut filter that cuts infrared light. 20, a condenser lens 21 for collecting the light beam, a total reflection mirror 22 that totally reflects the light beam, a separator diaphragm 23 that restricts the light beam, a separator lens 24 that re-images the light beam, a photoelectric conversion element array described later, and It is composed of an AF sensor 25 or the like comprising the processing circuit.

  The details of the focus detection optical system in the focus detection device 12 will be described with reference to FIG. 4 showing the configuration of the optical system. As the focus detection optical system, the photographing lens 13 and the field mask 19 from the subject side (left side in FIG. 4). The separator diaphragm 23 having openings 23a and 23b arranged substantially symmetrically with respect to the optical axis of the condenser lens 21 and the photographing lens 13, and the separator diaphragm 23 is arranged behind the corresponding openings 23a and 23b. Separator lenses 24a and 24b are arranged. In FIG. 4, the above-described total reflection mirror 22 and infrared cut filter 20 are omitted for the sake of simplicity of explanation.

In the focus detection optical system, the light flux from the subject incident through the region 13a or the region 13b of the photographing lens 13 is a field mask 19, a condenser lens 21, and an opening 23a and a separator of the separator diaphragm 23. First and second photoelectric conversion elements arranged on the photoelectric conversion element array 27 that is a focus detection element in the AF sensor 25 through the lens 24a or the opening 23b of the separator diaphragm 23 and the separator lens 24b. Re-imaging is performed on the arrays 27a and 27b.
The first and second photoelectric conversion element arrays 27a and 27b are disposed corresponding to the separator lenses 24a and 24b.

  When the photographic lens 13 is in a focus position and a subject image I is formed on the imaging plane G, the subject image I is perpendicular to the optical axis O by the condenser lens 21 and the separator lenses 24a and 24b. The image is re-imaged on the photoelectric conversion element array 27 on the secondary image forming surface to become the first image I1 and the second image I2.

  When the photographic lens 13 is at the front pin position and a subject image F is formed in front of the imaging plane G, the subject images F are perpendicular to the optical axis O in such a manner that they are close to the optical axis O by each other. To form a first image F1 and a second image F2.

  Further, when the photographic lens 13 is at the rear pin position and the subject image R is formed behind the imaging plane G, the subject images R are separated from the optical axis O by the mutual, and are aligned with the optical axis O. On the other hand, it is re-imaged perpendicularly to form a first image R1 and a second image R2.

  By detecting the interval between the first image and the second image described above, the in-focus state of the photographic lens 13 can be detected including the front pin and the rear pin. Specifically, the focused state is detected by obtaining the light intensity distribution of the first image and the second image from the output signal of the photoelectric conversion element array 27 and measuring the distance between the two images.

  The separator lenses 24a and 24b are integrally formed of an optical plastic material such as acrylic or polycarbonate, and contraction and expansion occur due to environmental temperature. For this reason, the distance between the first image and the second image in the in-focus state varies depending on the temperature, which becomes a focus detection error. FIG. 5 shows a focus detection area 31 in the photographing screen 30 in the focus detection optical system described above.

Here, the camera body side electric control circuit built in the camera body 10 will be described with reference to the block diagram of the electric control circuit of FIG.
The camera body side electric control circuit includes a controller (system controller) 35 which is a camera control device. The controller 35 includes, for example, a CPU (central processing unit) 36, a ROM 37, a RAM 38, an EEPROM 39, and the like. An A / D converter 40 is included. In addition to the control units for controlling the camera, the controller 35 executes a correction unit that corrects the defocus amount, a time measurement unit that measures the time after the focus detection unit is turned on, and a repeated focus detection operation. In addition, control means for repeatedly performing temperature detection is incorporated.

  The CPU 36 in the controller 35 performs a series of camera operation control in accordance with the camera sequence program stored in the ROM 37. Further, the EEPROM 39 can store correction data relating to AF control, photometry, etc. for each camera body 10.

  The controller 35 includes a plurality of body mount contact portions 59 that are connected to the lens mount contact portion 79 (FIG. 7) on the interchangeable lens side when the interchangeable lens 11 is attached to the camera body 10, the AF sensor 25, and the photometry portion 53. A flash unit 54, a mirror drive unit 55, a shutter drive unit 56, an image sensor drive unit 57, a display unit 58, a first release switch (hereinafter referred to as 1RSW) 41, and a second release switch ( (Hereinafter referred to as 2RSW) 42 is connected.

  The controller 35 communicates with the lens controller 61 (FIG. 7) in the interchangeable lens 11 via the mount contact portion 59, and exchanges various corrections and correction data in the camera body 10 and the interchangeable lens 11. A control signal for focus and aperture drive in the lens 11 is exchanged to perform each control.

  The AF sensor 25 includes a photoelectric conversion unit 80 including a photoelectric conversion element array (sensor array) 27, a processing circuit 81, and the like. An image signal corresponding to the subject image formed on the photodiode array 91 (FIG. 8) of the photoelectric conversion unit 80 is generated by the control signal from the controller 35, and the generated image signal is output to the controller 35. Is done.

  The photometry unit 53 generates an output corresponding to the luminance of the subject. The controller 35 A / D converts the photometric output by the A / D converter 40 and stores it in the RAM 38 as a photometric value.

  The flash unit 54 is used for photographing at low luminance, and the controller 35 controls charging, light emission timing, and light emission amount. The strobe unit 54 is also used as auxiliary light during AF operation, and intermittently emits light with a predetermined light emission amount in synchronization with the accumulation timing of the AF sensor 25.

  The mirror driving unit 55, the shutter driving unit 56, and the image sensor driving unit 57 are controlled by the controller 35, and respectively perform the driving of the shutter 28, the driving of the imaging device 29, and the driving operation of the main mirror 14 and the sub mirror 17 described above. Do.

  Further, the display unit 58 incorporates an LCD, an LED, and the like, and displays a camera shooting mode, a shutter speed, an aperture value, and the like.

  1RSW 41 and 2RSW 42 are switches that are linked to a release button operation (not shown). The 1RSW 41 is turned on when the release button is pushed down in the first stage, and the 2RSW 42 is turned on when the release button is pushed down. The controller 35 performs photometry and AF when the 1RSW 41 is turned on, and performs an exposure operation and an image reading operation from the image sensor 29 when the 2RSW 42 is turned on.

Next, the interchangeable lens side electrical control circuit built in the interchangeable lens 11 will be described with reference to the block diagram of the electrical control circuit in FIG.
The interchangeable lens side electric control circuit has a lens controller 61 which is a control device for the interchangeable lens 11. The lens controller 61 includes, for example, a CPU (central processing unit) 62, a ROM 63, a RAM 64, an EEPROM 65, and the like. An A / D converter 66 is included.

  The CPU 62 in the lens controller 61 performs a series of operation control of the interchangeable lens according to the interchangeable lens sequence program stored in the ROM 63. The EEPROM 65 can store correction data and adjustment data related to AF control, photometry, etc. for each interchangeable lens.

  Further, the lens controller 61 includes a plurality of lens mount contact portions 79 connected to the body mount contact portion 59 on the camera body 10 side when the interchangeable lens 11 is attached to the camera body 10, a lens drive portion 67, and a focus encoder. 69, the zoom encoder 74, and the aperture driving unit 71 are connected.

  The lens controller 61 communicates with the controller 35 in the camera body 10 via the lens mount contact portion 79 to exchange various adjustments and correction data in the camera body 10 and the interchangeable lens 11, and in the interchangeable lens 11. Control values for focus and aperture drive are exchanged.

  The lens driving unit 67 is controlled by the lens controller 61 and drives a lens motor (ML) 68 to drive the focus lens 13A in the photographing lens 13 to advance and retreat. The focus encoder 69 detects the movement position of the focus lens 13 </ b> A and outputs the detection result to the lens controller 61. The lens controller 61 controls the position of the focus lens 13A based on this movement position information.

  The zoom ring 26 provided in the interchangeable lens 11 is an operation member operated by a photographer, and the zoom system lens 13B in the photographing optical system is driven to advance and retreat to a zoom position that gives a desired focal length f according to the amount of rotation. Is done. The zoom encoder 74 detects a movement amount signal corresponding to the focal length f of the zoom lens 13 </ b> B and outputs it to the lens controller 61.

  The aperture driving unit 71 is controlled by the lens controller 61 and drives the aperture 18 in the photographing lens by an aperture motor (MA) 72 which is a stepping motor.

  Next, details of the AF sensor 25 will be described with reference to FIGS.

  As described above, the AF sensor 25 incorporated in the camera body side electric control circuit includes the photoelectric conversion unit 80 including the photoelectric conversion element array (sensor array) 27, the processing circuit 81, and the like. It is formed as a one-chip IC in which each component including the photoelectric conversion element array 27 and the temperature detection unit 85 is provided on one substrate.

  The photoelectric conversion unit 80 includes a photodiode array 91 that generates a photoelectric charge according to the amount of irradiated light, a shift gate 92, a shift register 93 that transfers the charge, an output buffer 94 of the shift register 93, Each element includes a monitoring photodiode 95 and the like arranged in the vicinity of the photodiode array. An image signal corresponding to the subject image formed on the photodiode array 91 of the photoelectric conversion unit 80 is generated by the control signal from the controller 35, and this image signal is output to the controller 35.

  As shown in FIG. 8, the processing circuit 81 controls the charge transfer from the photodiode array 91 to the shift register 93, controls the charge transfer in the shift register 93, and controls the signal processing timing of the analog processing section described later. The data output control unit 82 for performing the above, the integration control unit 84 for controlling the integration time and the like of the photoelectric conversion unit 80, the analog signal processing unit 83 for processing the analog signal from the photoelectric conversion unit 80, and sensitive to temperature changes. The temperature detection unit 85 is a temperature detection unit for supplying temperature information to the controller 35, the I / O control unit 86 to which an external terminal is connected, and the like.

  The data output control unit 82 generates a transfer clock for driving the shift register 93 based on a signal supplied from the controller 35 through the I / O control unit 86. In addition, a timing signal for switching a signal output from the AF sensor 25 to the outside is given to the analog signal processing unit 83.

  The integration control unit 84 causes the photoelectric conversion unit 80 to start integration, monitors the output of the monitoring photodiode (MPD) 95 during the integration operation, and reaches an appropriate integration amount based on the monitoring result. Is detected, and a shift gate pulse to the shift gate 92 is generated to complete the integration operation and control the integration time. Then, communication is performed with the controller 35 via the I / O control unit 86, and an integration completion signal is output to the controller 35. Further, the integration control unit 84 forcibly ends the integration by the forced integration end signal T3 from the controller 35 when the integration amount in the photoelectric conversion unit 80 does not reach a predetermined amount within a predetermined time. Let

  The analog signal processing unit 83 performs various analog processing such as dark output signal compensation and automatic gain control on the pixel signal from the shift register 93 via the output buffer 94 and an A / D conversion unit of the controller 35. After performing processing such as reference voltage clamping to match the dynamic range of the pixel signal, a pixel signal (sensor data) is output as an analog output signal T5 to the A / D converter 40 of the controller 35 via the analog output terminal 96a of the switch SW96. Output.

The I / O control unit 86 has a function of an interface between each block and the controller 35. External terminals 86a to 86d of the AF sensor 25, which are input / output of the I / O control unit 86, are input / output terminals for the following signals. That is,
The external terminal 86a is an input terminal for the integration start signal T1.
The external terminal 86b is an output terminal for the integration completion signal T2.
The external terminal 86c is an input terminal for an integration forced end signal T3 for forcibly terminating the integration.
The external terminal 86d is an input terminal for a read clock signal (A / D conversion synchronization clock signal) T4 from the controller 35 at the time of reading a pixel signal.

  The temperature detection unit 85 is a detection unit that performs temperature detection for electrically performing temperature compensation in order to eliminate a ranging error caused by a temperature change due to the focus detection optical system shown in FIG. It is. FIG. 9 shows a circuit of the temperature detection unit 85. In this circuit, resistors R1 and R2 having different temperature characteristics are connected in series between a predetermined reference voltage and GND, and the output at the connection point is detected by temperature. The signal is VTEMP. For example, if the resistor R1 is an ion-implanted resistor having a temperature coefficient βRl = 5000 ppm and the resistor R2 is a polysilicon resistor having a temperature coefficient βR2 = 500 ppm, a temperature-dependent voltage is generated at both ends of the resistor R1 due to a difference in temperature characteristics. To do. This voltage is output from the temperature detector 85. FIG. 10 shows an example of the temperature characteristic of the output of the temperature detector 85 (the voltage across the resistor R1).

  Of the pixel output signals output from the analog signal processing unit 83 in accordance with the read clock signal, the signals from the top to the predetermined output are dummy pixel signals (light-shielded pixels and the like) that are unnecessary for the distance measurement calculation. Therefore, the temperature detection signal VTEMP is output to the controller 35 as the analog output signal T5 through the same analog signal output terminal 96a in place of the pixel output signal unnecessary until the predetermined number.

  A switch SW96 is provided at a connection portion between the analog signal processing unit 83 and the temperature detection unit 85, and a switch control signal is supplied from the data output control unit 82 to the switch SW96 to switch between the pixel signal and the temperature detection signal. Is done.

  The photographing sequence processing operation in the camera 100 of the present embodiment having the above-described configuration will be described with reference to the flowchart of the main routine of FIG. 11, the flowcharts of the subroutines of FIGS. 12 to 15, the time chart of FIG.

  The main routine and subroutine of the photographing sequence process are routines according to the operation control procedure of the controller 35 shown in FIG.

  First, when the operation of the controller 35 is started by turning on the power of the camera or returning from the sleep state, the main routine of FIG. 11 is executed under the control of the controller 35. In step S1, the "initialization process" of the subroutine shown in FIG. 12 is called and executed.

  In the initialization process, various correction data for AF, photometry, etc. stored in advance in the EEPROM 39 in step S20 are read and developed in the RAM 38, and the lens data in the interchangeable lens is transferred to the controller 35 in the body. Initialization of each block such as acquisition through communication with the lens controller 61 and development on the RAM 64 and RAM 38 is executed.

  Subsequently, in step S21, the AF sensor 25 is turned on. In step S22, the time measuring timer for measuring the time from the power-on of the AF sensor 25 is started, and the process returns from this subroutine to the main routine.

  Returning to the main routine, it is determined in step S2 whether or not the 1RSW 41 is turned on. If 1RSW 41 is not turned on, the process proceeds to step S10, and a subroutine "always ranging" shown in FIG. 14 is executed (described later). If 1RSW 41 is on, the process proceeds to step S3, and the subroutine “AF” shown in FIG. 13 is executed.

  The subroutine “AF” will be described in detail later, but in this AF process, the focus state (subject distance state) of the subject is detected, and the focus detection result is transmitted to the lens controller 61 in the interchangeable lens 11. Is done. The lens controller 61 drives the focus lens 13A to the in-focus position based on the focus detection result, and performs AF for focusing on the subject.

  Thereafter, the process returns to the main routine, and in step S4, it is determined whether or not the result of the AF operation is in focus. If it is not focused in step S4, the process proceeds to step S9 described later. On the other hand, if it is in focus, the process further proceeds to step S5.

  In step S5, photometry is performed in which the photometry unit 53 is operated to measure the subject brightness in order to determine the exposure amount.

  Subsequently, in step S6, it is determined whether or not the 2RSW 42 is turned on. If the 2RSW 42 is not turned on, the process proceeds to step S9 described later, and if it is turned on, the process proceeds to step S7.

  In step S7, exposure is performed. That is, the aperture value determined based on the photometric value obtained in step S5 is transmitted to the lens controller 61. The lens controller 61 controls the aperture driving unit 71 to narrow down the aperture 18 of the photographing lens to a certain aperture value. Subsequently, the shutter 28 is controlled by the shutter driving unit 56, and the shutter 28 is opened for a predetermined time determined based on the photometric value obtained in the above step S5 and the exposure operation is performed. At the time of exposure, it is determined whether or not strobe light emission is necessary based on the photometric value. If necessary, a light emission signal is output to the strobe unit 54 with the shutter fully open to emit light. When the shutter operation is completed, the process proceeds to step S8, the aperture 18 is returned to the open state, the image data is read from the image sensor 29 by the image sensor driving unit 57, and the series of image capturing operations is completed.

  Subsequently, the process proceeds to step S9, where whether or not a predetermined sleep time has elapsed is measured by a sleep time measurement timer and checked. When the sleep time elapses, the CPU shifts to a CPU sleep state (power saving mode) in which the camera is turned off.

  If the subroutine “always-ranging” is called in step S10 of the main routine, only the ranging operation is performed, and the regular ranging without lens driving is performed. Thereafter, the process proceeds to step S9. As the camera operation, only the distance measurement operation, that is, the distance measurement operation is repeatedly executed until the operation of 1RSW 41 is performed. The latest distance measurement information is always updated by this constant distance measurement operation. When the 1RSW 41 is turned on and the AF operation is performed, that is, by adopting the latest distance measurement information in steps S2 and S3 of the main routine, the distance measurement operation for one time can be omitted, and the time lag in the AF operation Can be reduced.

Details of the subroutine “always ranging” process will be described with reference to a flowchart of FIG. 14 and a time chart of integration and reading operations in the AF sensor of FIG.
The processing of this subroutine is also executed under the control of the controller 35. As shown in FIG. 14, in step S200, the integration start signal T1 is output from the terminal 86a to the AF sensor 25 (rising from L → H), and the accumulation operation is started. In the following description, accumulation and integration indicate the same operation.

  In step S201, it is determined whether or not the accumulation (integration) time has reached a predetermined limit time with reference to a counter in the controller 35. If not, the process proceeds to step S202. If it has reached, the process proceeds to step S203.

  In step S202, whether or not the accumulation operation of the AF sensor 25 has been completed is checked by taking in the integration end signal T2 which is the output of the AF sensor 25 from the terminal 86b. When the integration end signal is output (rising from L → H), the process proceeds to step S204.

  On the other hand, when the process proceeds to step S203, a forced integration end signal T3 is given from the terminal 86c to the AF sensor 25 (rising from L → H), the accumulation operation is forcibly terminated, and the process proceeds to step S204.

  In step S204, a read clock signal T4 is supplied from the terminal 86d to the AF sensor 25, and the temperature detection signal VTEMP of the temperature detection unit output as the analog output signal T5 from the output terminal 96a is read. This readout period is a period corresponding to a period in which a dummy pixel (light-shielded pixel or the like) signal unnecessary for distance measurement calculation is output from the analog signal processing unit 83. During this period, the control signal of the switch SW96 is a temperature detection signal. Set to signal VTEMP side.

  Subsequently, in step S205, the read clock signal T4 is given, and the control signal of the switch SW96 is set on the pixel signal output side, and the image signal accumulated in the AF sensor 25 is output from the output terminal 96a as the analog output signal T5 as sensor data. (Pixel data) is output and read out.

  As described above, when the read clock is input from the controller 35 to the AF sensor 25, the temperature detection signal VTEMP and the sensor data are output from the AF sensor 25 in a predetermined order in synchronization therewith. The controller 35 sequentially A / D converts this sensor data by the A / D converter 40 and stores it in the RAM 38. When a read clock signal corresponding to the predetermined number of pixels is output, the read operation is terminated.

  Subsequently, distance calculation is performed based on the sensor data stored in the RAM 38 in step S206, and a defocus amount DF described later is obtained. Further, in step S207, a subroutine “temperature correction I” shown in FIG. 16 is called, temperature correction based on the temperature detection signal VTEMP with respect to the result of the distance calculation is executed, and a defocus amount DF ′ after correction described later. Is required. Thereafter, the process returns to the main routine.

  The subroutine “temperature correction I” processing will be described with reference to the flowchart of FIG. The processing of this subroutine is also executed under the control of the controller 35. First, in step S300, an average process is performed on the detection signal VTEMP data of the temperature detection unit 85 captured during the constant distance measurement operation. As described in the main routine of FIG. 11, when the 1RSW 41 is not turned on, the distance measurement is repeatedly performed. The temperature detection signal VTEMP data acquired at this time is stored as a statistical process for the latest predetermined number of times, for example, 20 times, and averaged to generate temperature data with repeated detection errors removed. .

  When the camera power is turned off or when the CPU enters the sleep state, the stored temperature data is cleared, and the newest temperature data is repeatedly taken in by turning on the power or returning from the sleep state. . Further, for example, when only the number of data less than 20 has been acquired, the averaging process is performed with the smaller number of data.

Subsequently, in step S301, a correction calculation is performed based on the average temperature data. In this correction calculation process, the defocus amount DF ′ after temperature correction with respect to the defocus amount DF before temperature correction is obtained by the following temperature correction equation. That is,
DF ′ = DF + KT × (VTEMP−VTEMP0) (1)
Here, KT is a temperature correction coefficient including temperature characteristics of the focus detection optical system (FIG. 4) and other temperature characteristics inside the camera.
As VTEMP, a value obtained by averaging the output values of the detection signal VTEMP of the temperature detection unit described above is adopted.
VTEMP0 is a reference temperature data value, and is an output value of the temperature detection unit output VTEMP when the reference temperature is 25 ° C.

  As described above, in the processing of the subroutine “temperature correction I”, the average value of the repeatedly acquired temperature data is obtained, and the temperature correction is performed based on the average value, whereby more accurate distance measurement information can be obtained. According to this corrected distance measurement information, it is possible to reduce detection errors caused by repetitive variations and disturbance noise that occur randomly.

Next, the subroutine “AF” called in step S3 of the main routine of FIG. 11 will be described with reference to the flowchart of FIG.
The processing of this subroutine “AF” is also executed under the control of the controller 35. First, in step S100, the integration start signal T1 is output to the AF sensor 25 to start the accumulation operation control. In step S101, it is determined whether or not the accumulation time has reached a predetermined limit time with reference to the counter in the controller 35. If not, the process proceeds to step S102. When the limit time is reached, the process proceeds to step S103.

  In step S102, it is checked whether or not the accumulation operation of the AF sensor 25 is completed with reference to the integration end signal T2 which is the output of the AF sensor 25. After confirming the completion of integration, the process proceeds to step S104.

  On the other hand, when the process proceeds to step S103, the forced integration end signal T3 is output to the AF sensor 25 to forcibly terminate the accumulation operation, and the process proceeds to step S104.

  In step S104, the read clock signal T4 is given to the AF sensor 25, and the temperature detection signal VTEMP which is temperature sensor data is read. Note that the processing in this step is the same as that in step S204 of the subroutine “always ranging”.

  Further, in step S105, the readout clock signal T4 is continuously supplied to the AF sensor 25, and the pixel signal accumulated in the AF sensor 25 is read out as sensor data. The process in this step is the same as that in step S205 of the subroutine “always ranging”.

  As described above, the read clock signal T4 is input from the controller 35 to the AF sensor 25, and the temperature detection signal VTEMP and sensor data (pixel data) are output from the output terminal 96a of the AF sensor 25 in synchronization therewith. In the controller 35, the sensor data (pixel data) is sequentially A / D converted by the A / D converter 40 and stored in the RAM 38.

  Thereafter, based on the sensor data (pixel data) stored in the RAM 38 in step S106, the distance calculation is performed and the defocus amount DF in a state where the temperature is not yet corrected is obtained. Note that the processing in this step is also the same processing as that in step S206 of the subroutine “always ranging”.

  Subsequently, the process proceeds to step S107, and the subroutine “temperature correction I” is called and executed. This process is the same as the flowchart of FIG. 16 described above, and a temperature correction is performed on the defocus amount DF as a result of the distance measurement calculation to obtain a corrected defocus amount DF ′.

  In step S108, it is determined whether or not the corrected defocus amount DF ′ after the distance measurement calculation and temperature correction is within the in-focus range. If it is in focus, the AF operation of this subroutine ends, and the process returns to the main routine of FIG.

  On the other hand, in the case of out-of-focus, the process proceeds to step S109 and lens driving based on the defocus amount is executed. That is, the lens drive command is transmitted from the controller 35 to the lens controller 61. Further, the defocus amount is transmitted to the lens controller 61. The lens controller 61 calculates the lens drive amount based on the defocus amount, and the drive control of the focus lens 13A is executed. Thereafter, returning to step S100, the distance measuring operation is performed again, and the loop of the distance measuring operation and the lens driving is repeated until focusing is achieved.

  After the AF process is executed and the process returns to the main routine, the camera 100 is brought into focus by turning on the LED in the finder that is focused on the display unit 58 or generating a PCV (not shown). It will be notified.

  According to the focus adjustment apparatus of the first embodiment described above, the temperature correction of the defocus amount is performed by averaging a plurality of predetermined temperature data detected by the temperature detection unit 85 provided in the IC chip of the AF sensor 25. Accordingly, accurate temperature correction is possible, and high-precision focus adjustment can be performed.

Next, an interchangeable lens camera on which the focus detection apparatus according to the second embodiment of the present invention is mounted will be described with reference to FIGS.
FIG. 17 is a diagram showing changes in temperature data (temperature detection signal VTEMP) with respect to an elapsed time after the power supply of the AF sensor is turned on. FIG. 18 is a flowchart of a subroutine “Temperature Correction II” called by the subroutines “always ranging” and “AF” in the shooting sequence of the camera of the present embodiment.

  In the camera of the present embodiment, the subroutine “Temperature Correction II” is applied instead of the subroutine “Temperature Correction I” in the shooting sequence of the camera 100 of the first embodiment. The AF sensor 25 starts operating when the power is turned on, and current consumption flows through the IC chip, so that the temperature of the IC chip itself rises. Therefore, when the power is turned on, temperature data indicating a temperature substantially equal to the environmental temperature is output, but the temperature of the IC chip rises with the passage of time, and the value of the detected temperature data also changes, and correct temperature correction is performed. There is a possibility not to be broken. Therefore, in the subroutine “temperature correction II” in the present embodiment, temperature data closer to the environmental temperature immediately after the AF sensor 25 is turned on is employed in order to reduce the detection error due to the rise in the IC chip temperature. I am doing so. Specifically, the temperature data acquired at the time of constant distance measurement is limited to adopt the temperature data acquired within a predetermined period after the AF sensor 25 is turned on. Other processing routines and the configuration of the camera are the same as those in the first embodiment. Hereinafter, different processes will be described.

  The temperature correction process called during the subroutines “always ranging” and “AF” in the shooting sequence of the camera of the present embodiment is the subroutine “temperature correction II” shown in FIG. 18, and the control of the controller 35 is also performed in this subroutine. Processed originally. That is, as shown in the flowchart of FIG. 18, it is checked in step S500 whether or not a predetermined time has elapsed since the AF sensor 25 was turned on. The elapsed time from turning on the power is the count value (measurement time) of the timer built in the controller 35 which starts counting from the power-on of the AF sensor 25 in step S22 in the subroutine “initialization process” shown in FIG. ) Is referenced. And when the said measurement time is smaller than predetermined determination time, it transfers to step S501. On the other hand, if larger, the temperature data detected here is not adopted, and the process proceeds to step S502 as it is.

  In step S501, the latest 20 times of the temperature detection signal VTEMP data, which is the temperature data of the temperature detector 85 repeatedly measured, is averaged to obtain temperature data from which the repeated detection error is removed.

  In step S502, based on the averaged temperature data or the previous average temperature data, temperature correction is performed on the detected defocus amount DF in the same manner as in step S301 in the subroutine “temperature correction I”.

  As described above, in this subroutine, when the determination time has elapsed in step S500, the temperature data that has been averaged last within the determination time is not subjected to the process of newly averaging and updating the temperature detection data. The stored data is used and the subsequent temperature correction is performed.

  According to the camera to which the focus adjustment apparatus of the present embodiment is applied, it is possible to reduce a detection error due to an increase in the temperature data value accompanying the temperature rise with the lapse of time of the IC chip, perform accurate temperature correction, Accurate ranging and AF are possible.

  The focus adjustment device according to the present invention can be used as a focus adjustment device capable of performing accurate temperature correction without causing an increase in cost and capable of performing high-precision focus adjustment.

It is a block block diagram which shows one concept of the focus adjustment apparatus of this invention. It is a block block diagram which shows another one concept of the focus adjustment apparatus of this invention. It is sectional drawing which shows the main structures of the interchangeable lens camera which mounts the focus adjustment apparatus of 1st embodiment of this invention. It is a figure which shows the detailed structure and optical path of the focus detection optical system for guide | inducing object light to the photoelectric conversion element row | line | column in the focus adjustment apparatus of the camera of FIG. It is a figure which shows the focus detection area in the imaging | photography screen in the camera of FIG. It is a block block diagram of the camera body side electric control circuit of the camera of FIG. It is a block block diagram of the interchangeable lens side electric control circuit of the camera of FIG. It is a block block diagram of the AF sensor in the camera body side electric control circuit of FIG. It is a circuit diagram of the temperature detection part in the AF sensor of FIG. It is a figure which shows an example of the output characteristic in the temperature detection part of FIG. 3 is a flowchart of a main routine of shooting sequence processing in the camera 100. 12 is a flowchart of a subroutine “initialization process” called in the main routine of FIG. 11. 12 is a flowchart of a subroutine “AF” called in the main routine of FIG. 11. 12 is a flowchart of a subroutine “always ranging” called in the main routine of FIG. 11. 15 is a flowchart of a subroutine “temperature correction I” called by a subroutine “AF” in FIG. 13 and a subroutine “always ranging” in FIG. 14. FIG. 9 is a time chart of integration and reading operations in the AF sensor of FIG. 8. FIG. It is a diagram which shows the change of the temperature data with respect to the elapsed time after the power supply ON of the AF sensor applied to the interchangeable lens camera which mounts the focus adjustment apparatus of 2nd embodiment of this invention. 18 is a flowchart of a subroutine “temperature correction II” called by subroutines “always ranging” and “AF” in the camera photographing sequence of FIG. 17.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Focus detection element 2 ... Temperature detection means 3 ... Correction means 4 ... Time detection means 27 ... Photoelectric conversion element array (focus detection element)
35 ... Controller (control means, correction means, time measurement means)
80 ... photoelectric conversion part (focus detection element)
85 ... Temperature detector (temperature detector)
Subroutine "Temperature compensation I", "Temperature compensation II"
... Correction means Step S22 ... Time measurement means

Agent Patent Attorney Susumu Ito

Claims (3)

In a focus adjustment device that divides a subject image that has passed through a photographic lens into two images, measures the interval between the two images, finds the amount of deviation from the interval between the two images at the time of focusing, and obtains the defocus amount of the photographic lens ,
A focus detection element having a plurality of photoelectric conversion elements for forming the two images;
Temperature detection means provided on the same IC chip as the focus detection element;
Correction means for correcting the defocus amount detected according to the output of the temperature detection means;
Time measuring means for measuring the time since the focus detection element is powered on;
And the correction means corrects the defocus amount based on the output of the temperature detection means when the output of the time measurement means is smaller than a predetermined value. In a focus adjustment apparatus that divides a subject image that has passed through a photographing lens into two images, measures the distance between the two images, and obtains the amount of deviation from the distance between the two images at the time of focusing to obtain the defocus amount of the photographing lens. ,
A focus detection element having a plurality of photoelectric conversion elements for forming the two images;
Temperature detection means provided on the same IC chip as the focus detection element;
Correction means for correcting the defocus amount detected according to the output of the temperature detection means;
Control means for repeatedly performing a focus detection operation on the focus detection element and repeatedly performing temperature detection;
And the correction means performs a correction after statistically processing the output of the temperature detection means repeatedly detected. In a focus adjustment apparatus that divides a subject image that has passed through a photographing lens into two images, measures the distance between the two images, and obtains the amount of deviation from the distance between the two images at the time of focusing to obtain the defocus amount of the photographing lens. ,
A focus detection element having a plurality of photoelectric conversion elements for forming the two images;
Temperature detection means provided on the same IC chip as the focus detection element;
Correction means for correcting the defocus amount detected according to the output of the temperature detection means;
Time measuring means for measuring the time since the focus detection element is powered on;
Control means for repeatedly performing a focus detection operation on the focus detection element and repeatedly performing temperature detection;
And the correction means calculates a defocus amount based on a result of statistical processing of the output of the temperature detection means repeatedly detected for the output of the temperature detection means when the output of the time measurement means is smaller than a predetermined value. A focus adjusting device characterized by correcting.

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