JP4262034B2 - Optical device and camera - Google Patents

Description

The present invention relates to an optical device equipped with a storage type sensor that performs focus adjustment and photometry operation or distance measurement and photometry operation, and a camera equipped with the optical device.

  Recent advances in automatic exposure and focus adjustment in cameras, etc. are striking in recent years. Exposure adjustment is properly controlled in most shooting situations, and the focus adjustment detection area is the central part of the shooting screen or multiple areas. The product is at a stage where it can be fully used.

  Needless to say, this greatly depends on the development of the microcomputer as the brain for control and the advancement of the sensor for information input.

  The metering sensor for exposure control divides the shooting screen into multiple parts to accurately detect the light distribution, and the optimum control in various situations is judged by organically linking each detection result, etc. Is selected.

  On the other hand, the focus detection sensor for focus adjustment can be detected not only at the center of the shooting screen but also at a plurality of points such as 3 points and 5 points, which is much easier to use than in the early days. It has become a thing.

  However, a focus adjustment device that can focus anywhere as a surface (area) instead of a plurality of points on the shooting screen is desired as an ultimate form.

  In this case, it is easily imagined that the importance of exposure control corresponding to the focus detection point will increase from the present level, and it is very effective to use the sensor for focus detection and photometry as an implementation method.

  That is, various photometry is possible with the point corresponding to the focus detection area as the center, and the optimum correspondence in every scene can be realized.

  However, since the focus detection sensor generally uses an accumulation type photoelectric conversion element, the accumulation time cannot be ignored depending on the situation, and a long accumulation operation for focus detection and photometry misses a photo opportunity. You can fully anticipate the situation that will affect the shooting.

(Object of invention)
An object of the present invention is to provide an optical device and a camera that can shorten the time of a series of accumulation operations required for focus detection and photometry.

In order to achieve the above object, the present invention obtains a parallax of an object passing through the photographing lens from a sensor at a position optically equivalent to the photographing surface with respect to the photographing lens, and an output of the sensor. Focus detection means for detecting the defocus amount of the photographing lens, lens drive control means for controlling the driving of the focus adjustment optical system of the photographing lens based on the defocus amount, and photometric information from the output of the sensor A focus detection calculation operation for detecting the defocus amount based on the output obtained by performing the accumulation operation with the sensor and confirming whether the photographing lens has reached the in-focus area. In parallel with this, the sensor is an optical device that performs an accumulation operation for photometry by the photometry means, and the camera is equipped with the optical device .

  According to the present invention, it is possible to provide an optical device and a camera that can shorten the time of a series of accumulation operations required for focus detection and photometry.

  As shown in Example 1 and Example 2 below.

  FIG. 1 is a diagram according to the first embodiment of the present invention, and is an optical layout diagram of each component for obtaining a photometric value for focus detection and exposure calculation in a photographing screen.

  In FIG. 1, 1 is a photographing lens, 8 is a field lens, 9 is a secondary imaging lens, and 10 is an area sensor.

  On the two imaging screens 10 a and 10 b of the area sensor 10, light beams from different pupil positions of the photographing lens 1 are respectively guided and recombined at an imaging magnification determined by the field lens 8 and the secondary imaging lens 9. Imaged. The area sensor 10 is optically equivalent to the photographing film surface with respect to the photographing lens 1, and the imaging screens 10a and 10b each have a field of view equal to the photographing screen.

  FIG. 2 shows a layout when the detection optical system shown in FIG. 1 is applied to a camera.

  In FIG. 2, 6 is a quick return mirror, 18 is a pentaprism, 19 is a splitting prism, 20 is a reflection mirror, and others are the same as in FIG.

  FIG. 3 is a view of the layout of FIG. 2 as viewed from above the camera.

  With the configuration as described above, the focus state (defocus information) and the photometric value for each area of the shooting screen can be obtained from the imaging screens 10a and 10b having a predetermined parallax. Since this method is disclosed in detail in Japanese Patent Application No. 5-278433, etc., detailed description is omitted here.

  FIG. 4 is a block diagram showing an example of a specific circuit configuration of a camera including the above-described components. First, the configuration of each unit will be described.

  In FIG. 4, a PRS is, for example, a CPU (central processing unit), ROM, RAM, and a one-chip microcomputer having an A / D conversion function. The microcomputer PRS is a sequence of cameras stored in the ROM. -A series of camera operations such as automatic exposure control function, automatic focus adjustment function, film winding and rewinding are performed according to the program. For this purpose, the microcomputer PRS communicates with the peripheral circuit in the camera body and the in-lens control device using the communication signals SO, SI, SCLK, and the communication selection signals CLCM, CDDR, CICC, and the respective circuits and lenses. To control the operation.

  SO is a data signal output from the microcomputer PRS, SI is a data signal input to the microcomputer PRS, and SCLK is a synchronous clock of the signals SO and SI.

  The LCM is a lens communication buffer circuit that supplies power to the lens power supply terminal VL when the camera is in operation, and the selection signal CLCM from the microcomputer PRS is a high potential level (hereinafter abbreviated as “H”, low When the potential level is abbreviated as “L”), it becomes a communication buffer between the camera and the lens.

  When the microcomputer PRS sets the selection signal CLCM to “H” and sends predetermined data from the SO in synchronization with SCLK, the buffer circuit LCM receives the buffer signals of SCLK and SO via the camera-lens communication contact. LCK and DCL are output to the lens. At the same time, the buffer signal of the signal DLC from the lens is output to SI, and the microcomputer PRS inputs lens data from SI in synchronization with SCLK.

  DDR is a circuit for detecting and displaying various switches SWS, and is selected when the signal CDDR is “H”, and is controlled from the microcomputer PRS using SO, SI, and SCLK. That is, the display of the display member DSP of the camera is switched based on data sent from the microcomputer PRS, and the microcomputer PRS is notified of the on / off states of various operation members of the camera by communication. OLC is an external liquid crystal display device located above the camera, and ILC is a finder internal liquid crystal display device.

  SW1 and SW2 are interlocked with a release button (not shown), and the switch SW1 is turned on when the release button is pressed in the first stage, and then the switch SW2 is turned on when the second stage is pressed. The microcomputer PRS performs photometry and automatic focus adjustment when the switch SW1 is turned on, and performs exposure control and subsequent film winding using the switch SW2 as a trigger.

  Note that the switch SW2 is connected to the “interrupt input terminal” of the microcomputer PRS. Even when the program is executed when the switch SW1 is turned on, an interrupt is generated by turning on the switch SW2, and control can be immediately transferred to a predetermined interrupt program.

  MTR1 is a film feeding motor, MTR2 is a mirror up / down motor and a shutter spring charging motor, and forward drive and reverse drive are controlled by respective drive circuits MDR1 and MDR2. Signals M1F, M1R, M2F, and M2R inputted from the microcomputer PRS to the drive circuits MDR1 and MDR2 are motor control signals.

  MG1 and MG2 are shutter front curtain and rear curtain travel start magnets, which are energized by signals SMG1 and SMG2 and amplification transistors TR1 and TR2, respectively, and shutter control is performed by the microcomputer PRS.

  Note that film feeding and shutter control by the motor drive circuits MDR1 and MDR2 are not directly related to the present invention, and detailed description thereof will be omitted.

  A signal DCL input in synchronization with LCK to the microcomputer LPRS, which is an in-lens control device, is command data from the camera to the lens LNS, and the lens operation in response to the command is determined in advance. The microcomputer LPRS analyzes the command in accordance with a predetermined procedure, and operates the focus adjustment and aperture control, the operation status of each part of the lens (the drive status of the focus adjustment optical system, the drive status of the aperture, etc.) and various parameters from the output DLC. (Open F number, focal length, defocus amount vs. moving amount coefficient of the focus adjusting optical system, various focus correction amounts, etc.) are output.

In the first embodiment, an example of a zoom lens is shown. When a focus adjustment command is sent from the camera, the focus adjustment motor LTMR is sent by signals LMF and LMR according to the drive amount and direction sent simultaneously. When driven, the optical system is moved in the optical axis direction to adjust the focus. The amount of movement of the optical system is monitored by a pulse signal SENCF of the encoder circuit ENCF that outputs a number of pulses corresponding to the amount of movement by detecting the pattern of a pulse plate that rotates in conjunction with the optical system with a photocoupler. Counting is performed by a counter in the computer LPRS. When a predetermined movement is completed, the microcomputer LPRS itself sets the signals LMF and LMR to “L” to brake the motor LMTR.

  For this reason, once the focus adjustment command is sent from the camera, the microcomputer PRS, which is the camera control device, does not need to be involved in lens driving at all until the lens driving is completed. Further, when requested by the camera, the contents of the counter can be sent to the camera.

  When an aperture control command is sent from the camera, a known stepping motor DMTR for driving the aperture is driven according to the number of aperture stages sent simultaneously. Since the stepping motor can be controlled open, an encoder for monitoring the operation is not required.

  ENCZ is an encoder circuit associated with the zoom optical system, and the microcomputer LPRS receives the signal SENCZ from ENCZ and detects the zoom position. The lens parameter at each zoom position is stored in the microcomputer LPRS, and when there is a request from the microcomputer PRS on the camera side, a parameter corresponding to the current zoom position is sent to the camera.

  ICC is a focus detection and photometry area sensor (corresponding to the area sensor 10 in FIG. 1) and its drive circuit composed of a CCD or the like, and is selected when the signal CICC is “H”, and SO, SI, It is controlled by the microcomputer PRS using SCLK.

  φV, φH, and φR are area sensor output reading and reset signals, and a sensor control signal is generated by a driving circuit in the ICC based on the signal from the microcomputer PRS. The sensor output is amplified after being read out from the sensor unit, and input to the analog input terminal of the microcomputer PRS as an output signal IMAGE. The microcomputer PRS performs A / D conversion on the signal, and then converts the digital value to a predetermined value on the RAM. Store sequentially to the address. Focus detection and photometric calculation are performed using these digitally converted signals.

  In FIG. 4, the camera and the lens are represented as separate bodies (lens exchangeable). However, the present invention is not limited to these, even if the camera and the lens are integrated. Absent.

  Next, automatic focus adjustment and exposure calculation of the camera having the above configuration will be described according to the following flowchart.

  FIG. 5 is a flowchart of the overall rough camera sequence, which will be described below.

  When power supply to the circuit shown in FIG. 4 is started, the microcomputer PRS starts execution from step (001) in FIG.

  In step (001), the state of the switch SW1 that is turned on by pressing the release button in the first stage is detected. If it is off, the process proceeds to step (002), and all flags and variables are initialized. Then, it is detected in step (001) that the switch SW1 is turned on again.

  On the other hand, if the switch SW1 is turned on in step (001), the process proceeds to step (003) to start the camera operation. In step (003), the “AF control” subroutine is executed. Here, accumulation and readout of image signals for focus detection, focus detection calculation, focus detection area selection, lens drive start, and the like are performed.

  When the subroutine "AF control" is completed, the process proceeds to step (004). Here, the "AE control" subroutine for storing and reading image signals for photometry, detecting the state of various switches, displaying, and the like is executed. .

  When the subroutine “AE control” is completed, the process returns to step (001) again, and steps (003) and (004) are repeatedly executed until the switch SW1 is turned off.

  FIG. 6 is a flowchart of the “AF control” subroutine executed in step (003) of FIG.

  When this subroutine is called, first, in step (031), the "sensor driving" subroutine is executed. Here, accumulation and readout (A / D conversion) of image signals are performed after resetting the sensor for the focus detection operation. In the following step (032), a “focus detection” subroutine for performing actual focus detection calculation is performed. In the next step (033), an “area selection” subroutine for determining a target area for focus adjustment is performed. Basically, automatic selection based on near point priority within the area sensor is performed.

  In the next step (034), the “lens drive” subroutine is executed, that is, the lens is driven based on the defocus amount of the area determined in step (032). The “AF control” subroutine is terminated.

  FIG. 7 is a flowchart of the “sensor drive” subroutine executed in step (031) of FIG.

  When this subroutine is called, first, in step (311), the sensor is reset. Specifically, the reset operation is performed inside the ICC by simultaneously setting the control signals φV, φH, and φR to “H” for a predetermined time by the microcomputer PRS.

  In the following step (312), an accumulation start command is sent from the microcomputer PRS to start accumulation, and in the next step (313), the process waits until the accumulation is completed. When the accumulation is completed, in the next step (314), the control signals φV and φH are driven to sequentially read the sensor outputs, A / D conversion is performed by the microcomputer PRS, and the result is stored in the RAM. In step 315), the “sensor driving” subroutine is terminated.

  FIG. 8 is a flowchart of the “focus detection” subroutine executed in step (032) of FIG.

  When this subroutine is called, first, in step (321), it is determined whether or not the lens is currently stopped. If it is not stopped, it is not necessary to prepare for the photometric operation, so that the process directly proceeds to step (322). Then, a “focus detection calculation” subroutine for performing focus detection calculation using the image signal obtained in step (031) of FIG. 6 is executed. Here, the operation is to obtain the defocus amount DEF while driving the lens.

  When the defocus amount DFF is obtained, the process proceeds from step (323) to the “lens drive” subroutine of step (034) in FIG. 6 as it is.

  On the other hand, if the lens is stopped in step (321), in other words, if the lens is driven to the target position (focus position), the process proceeds to step (324), where Starts the accumulation operation. If this is in focus, it is a preparatory operation for the photometric operation. In other words, as will be described later, when it is determined that the in-focus state is obtained in the next step (326), the flow of the accumulation end detection in the “AE control” subroutine through step (327) [step (043) in FIG. 10]. This is to immediately move to.

  In the next step (325), a “focus detection calculation” subroutine for performing focus detection calculation using the image signal obtained in step (031) of FIG. 6 is executed in the same manner as in step (322). This focus detection calculation is performed to increase the focus probability because the lens does not always reach the in-focus position even when the lens is currently stopped, such as when the previous lens drive amount is large. As described in the next step (326) and subsequent steps, the focus detection result is shifted to the photometry operation using the area sensor used at the time of focus detection, or the operation of performing the focusing operation again. Used to determine whether to move to

  In the next step (326), it is determined whether or not the focus detection calculation result is in focus. If in focus, the "AE control" in step (004) in FIG. The process proceeds to a subroutine (more specifically, the process proceeds to step (043) in FIG. 10 described later).

  If the in-focus state is not achieved in the step (326), the "focus detection" subroutine is terminated through the step (328) as it is, and in this case, the next lens drive [step (034) in FIG. 6]. ], The lens is driven based on the focus detection result obtained in step (325). Even after such a flow, the accumulation operation (for the photometry operation) is started because it passes through the step (324), but the following “AF control” subroutine [FIG. Since this accumulation operation is reset in step (311)], there is no problem.

  FIG. 9 is a flowchart of the “lens drive” subroutine executed in step (034) of FIG.

  When this subroutine is called, first, in step (341), communication is made with the lens, and two data "S" and "PTH" are input.

  The lens coefficient “S” is “the coefficient of the moving amount of the focusing optical system versus the moving amount of the image plane” of the photographing lens. That is, it represents the amount of image plane movement of the photographing lens when the focusing optical system of the photographing lens is moved by a unit length in the optical axis direction. For example, in the case of a single lens of the entire extension type, since the entire photographing lens corresponds to the focus adjustment optical system, the movement of the focus adjustment optical system is directly the image plane movement of the photographing lens, and “S = 1”. In the case of a zoom lens, “S” varies depending on the position of the zoom optical system.

  On the other hand, “PTH” is a movement amount of the optical system per one output pulse of the encoder ENCF in conjunction with the movement of the focus adjustment optical system LNS in the optical axis direction. In the subsequent step (342), a value obtained by converting the detected defocus amount DEF in the selected focus detection region, and the amount of movement of the photographing optical system to be focused by S and PTH, into the number of output pulses of the encoder, so-called lens. The driving amount FP is obtained by the following equation.

FP = DEF · S / PTH
In the following step (343), the FP obtained in the above step (342) is sent to the lens to instruct the driving of the focus adjusting optical system, and in the next step (344), this “lens driving” subroutine is ended. To do.

  FIG. 10 is a flowchart of the “AE control” subroutine executed in step (004) of FIG.

  When this subroutine is called, it is first determined in step (041) whether the lens is stopped. If stopped, the process proceeds to the next step (042) to start accumulation for the photometric operation, and in the subsequent step (043), the accumulation is awaited.

  Here, if the focus is determined in step (326) in FIG. 8, since accumulation is started in step (324) in FIG. 8 as well, the accumulation end detection is performed in this step (043). It is a direct transition from the “Focus Detection” subroutine.

  If the accumulation is completed, the sensor output is read in step (044). Then, in the next step (045), a “photometric calculation” subroutine for obtaining an exposure control value from the photometric result is performed. As the calculation value, an accumulated charge amount, an accumulation time, a read gain, and the like are used.

  In the following step (046), the state of various switches is detected. In the next step (047), focus detection, photometry, and display according to the state of each switch are performed. In the subsequent step (048), this “AE control” is performed. The subroutine is terminated.

  When the lens is not stopped at step (041) (when it is determined that the lens is out of focus at step (326) in FIG. 8 and the lens is driven to the in-focus position by the next lens driving, etc.) Is moved directly to step (048).

  Next, the “photometric calculation” subroutine executed in step (045) will be described.

  When photometry is performed using a storage type photoelectric conversion element, elements used for calculation are storage time, read gain, and sensor output value. Each value at the reference luminance is also required for conversion to an absolute luminance value.

When the accumulation time, readout gain, and sensor output value at the reference luminance Ev value (E ₀ ) are T ₀ , G ₀ , and V ₀ , respectively, and E is T, G, and V, the following relational expressions hold.

E = E ₀ + log (T ₀ / T × G ₀ / G × V / V ₀ ) / log 2
Here, as a so-called flicker countermeasure, practically sufficient photometry can be performed with almost no problem if T is 10 ms or more.

  The setting readout gain is 20, 40, 80, and 160 times, and the sensor output value is 0 to 255 of 8-bit A / D conversion.

  In step (045) of FIG. 10, the above formula is executed to obtain the subject luminance Ev value E.

  Next, switching of area division of the sensor output will be described.

  FIG. 11 is a diagram illustrating one pixel configuration of two imaging screens of the area sensor 10.

  When used for focus detection, pixel region division and output region division are the same. That is, the output of one pixel is handled as one unit of output, the focus adjustment operation is performed with a high-definition image signal, and the focus is adjusted accurately.

  On the other hand, when used for photometry, for example, as shown in FIG. 12, the outputs are grouped (averaged) every several pixels (10 pixels in the figure) and handled as one unit of output. This is because it is not necessary to handle the subdivided data as it is in focus detection for photometry, but it is influenced by noise and the amount of calculation increases.

  Further, when the area shown in FIG. 13 is selected by area selection in the focus detection operation, divided photometry is also effective in which the area is the central area (0) and its periphery is divided into 6 as shown in FIG. . In this case, the average value of the pixel outputs in each area is used as the photometric output value, and the divided areas are not limited to this shape and can be set freely.

  In the first embodiment described above, the sensor output re-accumulated is used for the photometric calculation. However, in order to shorten the time more actively, the focused sensor output can also be used for the photometric calculation.

  In the following, changes to the first embodiment will be described.

  FIG. 15 is a flowchart of a “focus detection” subroutine corresponding to FIG. 8 of the first embodiment.

  The only change is that there is no accumulation start operation performed in step (324) of FIG. That is, in FIG. 15, the “focus detection calculation” subroutine is immediately performed in step (524), and the focus determination is performed in the next step (525). If in-focus, the process immediately proceeds to the “AE control” subroutine in the same manner as in FIG.

  FIG. 16 is a flowchart of an “AE control” subroutine corresponding to FIG. 10 of the first embodiment.

  The changes here are that the transition from the step (526) in FIG. 15 to the “AE control” subroutine is immediately before the “photometry calculation” subroutine in step (063), and the step in FIG. The operation from the series of accumulation start in (042) to (044) to the sensor signal readout is the execution of the “sensor drive” subroutine in step (062).

  That is, when it is determined that the focus is in focus in FIG. 15, photometry is also performed with the sensor signal used for the focus determination as it is, so that it is possible to immediately proceed to photometry calculation and go to steps (042) to (044) in FIG. The corresponding series of operations can be performed by executing the “sensor drive” subroutine as it is, and the flow chart is very simple.

  According to the first and second embodiments, it is determined whether or not the current lens position can be regarded as a focus position in order to shorten the photometric operation time when the lens is stopped immediately before the photographing (exposure) operation. If the accumulation operation for photometry is started before the start of the focus detection calculation for the purpose (Example 1), or if the result of the focus detection calculation after the lens is stopped is in focus, Since the sensor output obtained at the time of detection is used as it is for the photometric information calculation (Example 2), the delay in the shooting preparation operation due to the focus detection and the advanced function of the photometry is avoided, and comfortable operability is maintained. It will be drunk.

  On the other hand, the area division of sensor output is most subdivided and used at the time of focus detection, and is grouped and used every several pixels at the time of photometry. As a result, a precise distance measurement operation and appropriate and quick division photometry are possible. In other words, the sensor output can be used effectively, and the aread detection area is fully utilized.

(Modification)
The present invention describes an example in which the present invention is applied to a TTL single-lens reflex camera. However, the present invention can also be applied to a camera that performs external distance measurement. Furthermore, the present invention can be applied to other devices.

  In the first and second embodiments, the sensor output use area used for focus detection partially overlaps the use area used for photometry, but the sensor output actual use area is different in each. May be.

It is a perspective view which shows schematic structure of the detection optical system which concerns on Example 1 of this invention. It is a perspective view which shows the structure at the time of applying the detection optical system of FIG. 1 to a camera. It is a top view which shows a mode that the optical system of FIG. 2 was seen from the camera upper surface. FIG. 3 is a block diagram illustrating a configuration of each unit of the camera in FIG. 2. 5 is a flowchart showing a rough operation of the camera having the configuration of FIG. 4. It is a flowchart which shows the operation | movement performed in step (004) of FIG. It is a flowchart which shows the operation | movement performed in step (031) of FIG. It is a flowchart which shows the operation | movement performed in step (032) of FIG. It is a flowchart which shows the operation | movement performed in step (034) of FIG. It is a flowchart which shows the operation | movement performed in step (004) of FIG. It is a figure explaining one pixel structure of two imaging screens of the area sensor of FIG. It is a figure which shows the division area for photometry when the area | region for focus detection of FIG. 11 is selected. It is a figure which shows the example of the area | region selected at the time of focus detection operation | movement in Example 1 of this invention. It is a figure which shows the division area for photometry when the area | region for focus detection of FIG. 13 is selected. It is a flowchart which shows the operation | movement at the time of the focus detection in Example 2 of this invention. It is a flowchart which shows the operation | movement at the time of AE control in Example 2 of this invention.

Explanation of symbols

Microcomputer provided in the PRS camera ICC Focus detection and photometry sensor and drive circuit LCM Lens communication buffer circuit LNS lens LPRS Microcomputer provided in the lens

Claims (2)

A sensor that is optically equivalent to the photographing surface with respect to the photographing lens, and a focus detection unit that obtains the parallax of the object that has passed through the photographing lens from the output of the sensor and detects the defocus amount of the photographing lens And a lens drive control means for controlling the drive of the focus adjustment optical system of the taking lens based on the defocus amount, and a photometry means for detecting photometry information from the output of the sensor,
In parallel with the focus detection calculation operation for detecting the defocus amount based on the output obtained by performing the accumulation operation with the sensor and confirming whether the photographing lens has reached the in-focus area, An optical apparatus characterized in that a storage operation for photometry by the photometry means is performed by a sensor. A camera comprising the optical device according to claim 1 .

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