JP2004023580A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive digital camera having high function without giving a sense of incongruity to a photographer. <P>SOLUTION: A CPU 11 interrupts the updating of image display in an image display part 8 in accordance with the interruption of an operation of a zoom switch ST. Because the updating of the image display is interrupted in the image display part 8 even in such a case when an optical system driving motor moves lens groups 51 and 52 backward just before a zoom operation is ended, for example, for stopping backlash, only a frozen image is displayed without displaying an image in which a change in a viewing angle occurs in a backward direction. Therefore, the photographer has little possibility of feeling the sense of incongruity even if the photographer visually recognizes the image display part 8. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital camera, and more particularly, to a digital camera having a zoom function and an image display function.
[0002]
[Prior art]
With the improvement in electronic technology, digital cameras such as digital still cameras that convert captured images into digital data and store the data have been developed and are already on the market. A user can display an image captured by a digital camera on, for example, a display of his / her personal computer, and can print the image via a printer, so that the application range is wide.
[0003]
[Problems to be solved by the invention]
By the way, there is also a demand for miniaturization and cost reduction in digital cameras. However, an additional function such as a zoom function has an effect of increasing the value as a product, and therefore cannot be easily omitted even if it causes a size increase and a high cost. Therefore, a digital camera with a zoom function has been developed and is already on the market.
[0004]
Incidentally, the zoom operation can be achieved by driving a specific lens group in the optical axis direction in a photographing optical system including a plurality of lens groups. However, when power is transmitted from a motor as a drive source to a lens frame holding a lens group via a drive system including a gear train, it is necessary to consider backlash and the like of the drive system. Specifically, when the motor is driven in one direction (for example, from the wide side to the tele side), the backlash can be ignored, but the motor is driven in the opposite direction (for example, from the tele side to the wide side). In this case, even if the motor reaches the specified stationary position due to the backlash, the lens group may not yet reach the specified stop position. Therefore, in a digital camera with a zoom function according to the related art, when ending the zoom operation, the motor is temporarily stopped at a position advanced in the optical axis direction with respect to the stop position of the lens group, and then the motor is rotated reversely. Thus, after the backlash is removed, the lens group is stopped at the specified stop position. Japanese Patent Application Laid-Open No. 5-252474 discloses a silver halide camera regarding such backlash removal.
[0005]
However, in a general digital camera, when the power is turned on regardless of the operation of the release switch in order for the photographer to check the subject, the image is acquired at predetermined timings via an image sensor such as a CCD. There is an electronic finder function that can display a subject image on a monitor based on image data. According to such an electronic finder function, the subject image displayed on the monitor changes in angle of view in response to the zoom drive, so that the photographer has the advantage of being able to confirm through the monitor whether the desired angle of view has been obtained, When the motor is rotated in the reverse direction to eliminate the backlash as described above, a display is displayed in which the subject image that has been enlarged in response to the zoom operation is suddenly reduced just before the end of the zoom operation. Such a display may cause the photographer to feel uncomfortable.
[0006]
To solve such problems, it is possible to eliminate the backlash of the drive system to eliminate the sense of incongruity of the photographer.However, in order to eliminate the backlash of the drive system, it is necessary to improve the precision of parts. This leads to a significant increase in cost.
[0007]
The present invention has been made in view of the problems of the related art, and provides a digital camera having a high-performance yet inexpensive configuration that does not give a photographer an uncomfortable feeling based on a completely different idea from the conventional art. The purpose is to:
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a digital camera according to a first aspect of the present invention includes a photographing optical system having a plurality of lens groups, an optical image formed through the photographing optical system, and an image signal. An image sensor to output, based on an image signal output from the image sensor, a display unit that displays an image while updating at a predetermined timing, and moving a lens group of the imaging optical system in an optical axis direction, Driving means for performing driving for zoom operation; a zoom switch for causing the driving means to perform driving for zoom operation; and image display on the display unit in response to interruption of operation of the zoom switch. Control means for interrupting the updating of the display unit, even if the driving means moves the lens group in the reverse direction immediately before the end of the zoom operation, for example, to eliminate backlash, Since the update of the image display is interrupted, the image in which the angle of view change has occurred in the opposite direction is not displayed, and only the frozen image is displayed. There is little fear of feeling strange.
[0009]
Further, when the driving unit drives the lens unit in the reverse direction at least once and then stops in response to the interruption of the operation of the zoom switch, the effects of the present invention can be exhibited.
[0010]
Further, if the stop position of the lens group is determined in advance, the configuration of the digital camera can be further simplified.
[0011]
Further, it is preferable that the control means restarts updating the image display on the display unit after the lens group is stopped, so that the photographer can check the composition of the subject before photographing.
[0012]
In addition, the control unit is responsive to the operation of the zoom switch being interrupted only when the driving unit performs driving for a zoom operation in a specific direction (for example, from the tele side to the wide side). The update of the image display on the display unit may be interrupted. This is because when driving for a zoom operation is performed in a direction opposite to the specific direction, backlash may not be considered in some cases. Therefore, in this specification, the driving direction for the zoom operation taking the backlash into account is referred to as a specific direction.
[0013]
Further, the driving unit moves the lens group of the imaging optical system in the optical axis direction by power from a single driving source, and performs driving for a focusing operation and driving for a zoom operation. A so-called step zoom type camera can exhibit the effects of the present invention.
[0014]
A digital camera according to a second aspect of the present invention includes an imaging optical system including a plurality of lens groups, an imaging element that receives an optical image formed through the imaging optical system, and outputs an image signal, A display unit that displays an image while updating at a predetermined timing based on an image signal output from the element, and driving for a zoom operation by moving a lens group of the imaging optical system in an optical axis direction. A driving unit that performs the driving, a zoom switch that causes the driving unit to perform driving for a zoom operation, and an image displayed when the operation of the zoom switch is continued in response to the interruption of the operation of the zoom switch. Control means for displaying an image different from that on the display unit, so that the driving means moves the lens group in the opposite direction immediately before the end of the zoom operation, for example, to eliminate backlash. Even if, when the display unit displays the background color in place of the subject image, is small possibility that the photographer feels uncomfortable even if viewing the display unit. Note that “an image different from the image displayed when the operation of the zoom switch is continued” is an image (a background color, a wallpaper, a maker's logo, an anime character, In addition to a character image such as "Zooming", an image obtained by performing processing different from normal processing on an image signal obtained from the image sensor may be used. The different processing is performed on the image signal obtained through the image sensor, such as a monotone or sepia color change processing, a mosaic processing, a defocus processing, and a character such as "zooming". Processing for synthesizing images may be used. Alternatively, a process for obtaining an image or the like based on a low resolution (low pixel) obtained by image processing in a control circuit or the like may be performed. Any image may be used as long as the image is not recognized as the image.
[0015]
Further, when the driving unit drives the lens unit in the reverse direction at least once and then stops in response to the interruption of the operation of the zoom switch, the effects of the present invention can be exhibited.
[0016]
Further, if the stop positions of the lens groups are determined in advance, the configuration of the digital camera can be further simplified.
[0017]
Further, it is preferable that the control means restarts updating the image display on the display unit after the lens group is stopped, so that the photographer can check the composition of the subject before photographing.
[0018]
In addition, the control unit is responsive to the operation of the zoom switch being interrupted only when the driving unit performs driving for a zoom operation in a specific direction (for example, from the tele side to the wide side). The update of the image display on the display unit may be interrupted. This is because when driving for a zoom operation is performed in a direction opposite to the specific direction, backlash may not be considered in some cases.
[0019]
Further, the driving unit moves the lens group of the imaging optical system in the optical axis direction by power from a single driving source, and performs driving for a focusing operation and driving for a zoom operation. A so-called step zoom type camera can exhibit the effects of the present invention.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a camera according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external view showing an embodiment of a digital still camera 100 as an example of a digital camera to which the present invention is applied. FIG. 1A is a front perspective view of a digital still camera 100, and FIG. () Is a rear perspective view.
[0021]
In FIG. 1, an imaging unit 24 for capturing an image of a subject, an auxiliary light emitting unit 30 that emits auxiliary light to the subject, and an optical type that allows a photographer to check a composition including the subject by looking into the front of the digital still camera 100 are shown. An image display unit 8 for displaying a photographed image and the like, an information display unit (so-called status LCD) 26 for displaying a photographing setting status and the like, and an operation switch for setting and switching various functions are provided on the back of the viewfinder 25. (Switch) 21 and a release switch 21a for performing shutter release on the upper surface of the digital still camera 100. The detailed description of each component will be described together with the description of the functional configuration described later. In the present embodiment, the optical finder 25 has an optical system different from that of the lens unit 1.
[0022]
FIG. 2 is a block diagram showing a functional configuration of the digital still camera 100. In FIG. 2, a digital still camera 100 is a lens unit 1 (shown as a single unit in the figure), which is a photographing optical system including at least a front group lens (first lens group) and a rear group lens (second lens group). , Aperture 2, imaging unit 24 including CCD 3, imaging circuit 4, A / D conversion circuit 5, memory 6, D / A conversion circuit 7, image display unit 8, recording memory 9, compression / decompression circuit 10, CPU 11, TG 12 AE / AF processing circuit 13, CCD driver 14, aperture drive motor 15, aperture drive motor drive circuit 16, optical system drive motor 17, optical system drive motor drive circuit 18, battery 19, EEPROM 20, zoom switch ST as a zoom switch , An auxiliary light emitting unit 30 (also used as an auxiliary light emitting unit for AF and a red-eye reduction lamp). Kill), and a switching circuit 23. Although the lens unit 1 of the present embodiment has a first lens group and a second lens group, it goes without saying that more lens groups may be provided.
[0023]
The imaging unit 24 includes a lens unit 1 that captures an optical image of a subject, which will be described later, an aperture 2 that adjusts the amount of light transmitted through the lens unit 1 and adjusts exposure, and a subject that is formed on the optical path of the lens unit 1. The CCD 3 is configured by a CCD (Charge Coupled Device) 3 for photoelectrically converting the optical image of the above, and outputs a photoelectrically converted image signal (analog signal) to the imaging circuit 4. That is, the imaging unit 24 has a function as an imaging unit.
[0024]
The imaging circuit 4 performs various image processing such as sensitivity correction of the image signal input from the CCD 3 to generate a predetermined image signal in synchronization with the timing signal input from the TG 12, and outputs the predetermined image signal to the A / D conversion circuit 5. Output. The A / D conversion circuit 5 converts the input image signal from an analog signal to a digital signal, and outputs image data to the memory 6 or the AE / AF processing circuit 13 according to an instruction from the CPU 11.
[0025]
The memory 6 includes a buffer memory and the like, and temporarily stores the input image signal. When receiving an image display instruction from the CPU 11, the memory 6 outputs the image data instructed to display the image to the D / A conversion circuit 7, and the D / A conversion circuit 7 performs analog conversion on the input image data. At the same time, processing is performed so as to adapt to the output display, and the output is displayed on the image display unit 8. On the other hand, when receiving the image recording instruction from the CPU 11, the memory 6 outputs the image data instructed to record the image to the compression / expansion circuit 10, and the compression / expansion circuit 10 converts the input image data into, for example, a JPEG format. Output to the recording memory 9.
[0026]
The image display unit (also referred to as a display unit) 8 includes a TFT (Thin Film Transistor) or the like, and outputs and displays an image signal input from the D / A conversion circuit 7. The display is not limited to an image, and may be, for example, a text screen such as a menu screen for selecting a function.
[0027]
The recording memory 9 serving as a recording unit is a recording memory including a semiconductor memory and the like, and is a recording medium having an image data recording area for recording image data input from the compression / expansion circuit 10. The recording memory 9 may be, for example, a built-in memory such as a flash memory, a removable memory card or a memory stick, or a magnetic recording medium such as a hard disk or a floppy disk. You may. That is, the recording memory 9 has a function as a recording unit.
[0028]
When receiving an image read instruction from the CPU 11, the recording memory 9 outputs the read image data to the compression / expansion circuit 10, and the compression / expansion circuit 10 performs expansion processing of the input image data, and 6 is output.
[0029]
The compression / expansion circuit 10 compresses the image data input from the memory 6 by a predetermined encoding method, and converts the image data input from the recording memory 9 to display the read-instructed image data on the screen. And a decompression circuit for decoding and decompressing. That is, the compression / expansion circuit 10 has a function as compression / expansion means.
[0030]
A CPU (Central Processing Unit) 11 reads various application programs related to photography stored in the EEPROM 20 into a work area (not shown), executes various processes such as a photography process according to the programs, and displays a processing result on an image display unit. 8, or displayed on the information display unit 26.
[0031]
The CPU 11 controls the drive of the AE / AF processing circuit 13 in response to the half-press of the release switch 21a (FIG. 1), determines the exposure condition from the obtained photometric value, and detects the lens unit 1 by the AF process. Is driven to the in-focus position, performs an exposure process in response to the full depression of the release switch 21a, performs image processing and digital conversion on the generated image signal, temporarily stores it in the memory 6, and then stores the image signal in the compression / expansion circuit 10. The image data is compressed and output to the recording memory 9.
[0032]
A TG (Timing Generator) 12 generates a predetermined timing signal and outputs it to the imaging circuit 4, the CPU 11, and the CCD driver 14.
[0033]
An AE (Auto Exposure: automatic exposure control) / AF (Auto Focus: automatic focus control) processing circuit 13 includes an AE processing circuit for executing an AE process for detecting an appropriate exposure condition and an AF process for detecting a focus position. And an AF processing circuit to be executed. Each process is performed on image data input from the A / D conversion circuit 5 in accordance with an instruction from the CPU 11.
[0034]
In the AE processing, the AE processing circuit performs arithmetic processing such as cumulative addition on the input luminance value of one screen or a predetermined area in the screen, and determines an appropriate exposure condition at the time of actual exposure from the processing result. The calculated value is output to the CPU 11. On the other hand, in the AF processing, the AF processing circuit calculates an AF evaluation value for one input screen or a predetermined area in the screen, and outputs the calculation result to the CPU 11.
[0035]
This AF evaluation value has such a characteristic that it becomes larger as the focal point is in focus. When a graph is created with each lens position on the horizontal axis and the AF evaluation value on the vertical axis, a peak with the focal point at the top is formed. Is done. That is, by comparing the AF evaluation values obtained while moving the lens unit 1 with each other, the peak of the mountain, that is, the focal point can be obtained. The operation of obtaining the AF evaluation value in this manner is called a search operation. The AF evaluation value is calculated by analyzing the frequency of the image data for one input screen or a predetermined area in the screen. In the frequency analysis, a band-pass filter is configured as software, an integrated value of the intensity of an image signal that has passed through the band-pass filter is calculated, and the calculation result is used as an AF evaluation value. That is, the AF evaluation value is contrast (difference between light and dark) information, and is calculated by performing an operation for obtaining the intensity of a specific frequency included in the image.
[0036]
Here, the AF processing by the CPU 11 and the AF processing circuit will be described. The CPU 11 controls the driving of the optical system driving motor driving circuit 18 as a driving means to gradually generate an image signal by the CCD 3 at each lens position while moving the second lens group of the lens unit 1. The AE / AF processing circuit 13 calculates an AF evaluation value for each image data input from the A / D conversion circuit 5, compares the calculated AF evaluation values, and detects the lens position that is the maximum AF evaluation value as the focal point. Output to
[0037]
Upon receiving an instruction from the CPU 11, the CCD driver 14 drives and controls the CCD 3 in synchronization with a timing signal input from the TG 12. Specifically, control of the charge accumulation time of the CCD 3 according to the exposure adjustment control is executed.
[0038]
The aperture drive motor drive circuit 16 controls the drive of the aperture drive motor 15 according to an instruction from the CPU 11, and the aperture drive motor 15 drives the aperture 2. Further, the optical system drive motor drive circuit 18 controls the drive of the optical system drive motor 17 according to an instruction from the CPU 11, and the lens unit 1 is driven by the drive force of the optical system drive motor 17, whereby the lens unit 1 The first lens group and the second lens group move as described below.
[0039]
The battery 19 is a power source that supplies power to each component of the digital still camera 100. For example, a lithium battery or an alkaline dry battery is applied.
[0040]
An EEPROM (Electrically Erasable Programmable Read-Only Memory) 20 stores various application programs, processing programs, and the like related to imaging of the digital still camera 100.
[0041]
The operation switch (switch) 21 includes various operation switches such as a release switch 21a, a mode switch for switching functions, and a menu switch for selecting settings. When each switch is operated, a signal is generated and output to the CPU 11. The release switch 21a is composed of a two-stage switch composed of a half-press release switch for starting AE and AF processing prior to a shooting operation, and a full-press release switch for starting actual exposure processing.
[0042]
The flash light emitting unit 22 is a light emitting unit that emits a strobe light to a subject when the luminance of the surrounding environment detected at the time of shooting is insufficient, and the light emission timing and light emission amount are controlled by the switching circuit 23. In the present embodiment, the flash light emitting unit 22 includes a so-called pop-up mechanism so that it appears on the external appearance of the digital still camera 100 only when strobe light is emitted, but the present invention is not limited to this.
[0043]
Next, a configuration for achieving a zoom operation and a focusing operation by the step zoom method will be described. FIG. 3 is a schematic configuration diagram showing a lens barrel of the camera according to the present embodiment and a driving configuration thereof.
[0044]
In FIG. 3, reference numeral 17 denotes an optical system drive motor driven and controlled by the CPU 11, 17a denotes a sun gear fixed to the output shaft of the optical system drive motor 17, and 41 denotes a sun gear fixed to the output shaft of the optical system drive motor 17. A pinion gear, 42 is a Focus pulse plate held so as to rotate coaxially with the optical system drive motor 17, and 43 is a photo interrupter that optically detects a slit of the Focus pulse plate 42 and outputs a pulse corresponding to the rotation of the motor. .
[0045]
Reference numeral 44 denotes a gear train for transmitting the power of the pinion gear 2 to the gear 45 at a reduced speed; 46, a reference pulse plate held so as to rotate coaxially with the gear 45; 47, a gear 45 which optically detects a slit of the reference pulse plate 46; Is a photointerrupter that outputs a pulse corresponding to the rotation of.
[0046]
Reference numeral 50 denotes a lens barrel, which includes a fixed barrel 59, a cam barrel 57 rotatable around the optical axis by a driving force from a gear 62 in the fixed barrel 59, and a cam groove formed in the cam barrel 57. A first lens group holder 56 that holds a first lens group 51 (a single lens is shown in the figure, but a plurality of lens bodies may be used), and a second lens group 52 (a single lens is shown in the figure). And a second group holder 58 for holding a plurality of groups. It is needless to say that this embodiment can also be applied to a type having a multistage cam cylinder having a lens group for each of a plurality of cam cylinders having different diameters.
[0047]
The fixed cylinder 59 and the cam cylinder 57 are helicoidally coupled, and the cam cylinder 57 is rotated by receiving power from the optical system drive motor 17 via the sun gear 17a, the planetary gear 62, and the cam cylinder gear 57a. , Moves back and forth with respect to the fixed cylinder 59 in the optical axis direction. The first group holder 56 and the second group holder 58 are engaged with a cam groove (not shown) formed on the peripheral surface of the cam cylinder 57, and the first lens group 51 and the second lens group 51 are rotated by rotation of the cam cylinder 57. The two lens groups 52 are driven in the optical axis direction according to the cam grooves (or may be helicoid grooves). The CPU 11 controls all camera control operations.
[0048]
In the above configuration, since the Focus pulse plate 42 is directly driven by the optical system drive motor 17, the photo interrupter 43 generates a Focus pulse (control pulse signal), which is a fine-pitch signal, and inputs it to the CPU 11.
[0049]
On the other hand, since the reference pulse plate 46 is driven by the rotation of the motor reduced by the gear train 44 and the gear 45, the photo interrupter 47 generates a reference pulse (reference pulse position), which is a signal of a coarse pitch, to the CPU 11. input.
[0050]
Next, the drive control of the lens barrel 10 by the CPU 11 using the above-mentioned Focus pulse, reference pulse and absolute position signal will be described with reference to FIG.
[0051]
In FIG. 4, T1 and T2 indicate the movement trajectories when the first lens group 51 and the second lens group 52 zoom from f = 35 mm to f = 90 mm while maintaining the relationship of the afocal position.
[0052]
Further, T3 is a movement locus of the second lens group 52 in the step zoom system when focusing is performed by extending one group. FIG. 4 shows the trajectory T3 in a simplified manner, but the actual trajectory T3 is set to be different for each zoom position.
[0053]
In the present embodiment, by moving the first lens group 51 along the locus T1 and moving the second lens group 52 along the locus T3, f = 35 mm (WIDE), f = 50 mm (MIDDLE1), Five zoom positions, f = 70 mm (MIDDLE2), f = 80 mm (MIDDLE3), and f = 90 mm (TELE), can be selectively set.
[0054]
For example, in the case of a shooting state of f = 50 mm in the zooming operation, first, the lens groups 51 and 52 are on the WIDE side with respect to the reference pulse switching point (the falling point in the present embodiment, but may be the rising point) P1. At the position P2 as a standby position. Then, at this time, the CPU 11 detects switching of P1, counts a predetermined number of Focus pulses, stops the lens groups 51 and 52 at the standby position P2 without error, and confirms this. Then, the Focus pulse counter is reset in response to this confirmation.
[0055]
Here, such a standby position is similarly provided in each of the zoom positions, and by counting a predetermined number of Focus pulses from the switching of P1, the lens groups 51 and 52 correspond to the selected zoom position. It can be confirmed that the vehicle has stopped without any error at the standby position where it is performed.
[0056]
Note that the lens groups 51 and 52 are moved to the standby position as a method of driving the reference pulse from the detection point until the number of Focus pulses reaches a predetermined number corresponding to the standby position, and a method of detecting the position based on a continuous signal. There is a method of driving by going. When the camera starts operating according to the photographing operation of the photographer, the distance and luminance of the subject are measured, and then the focusing drive is started.
[0057]
At this time, based on the distance data, the number of Focus pulses (focusing target value) to be driven of the first lens group 51 from the detection of the reference pulse switching point P1 to be detected later is called from the memory in the CPU 11. It is.
[0058]
When the lens groups 51 and 52 move from the standby position P2 toward the TELE side and the signal of the reference pulse switching point P1 is detected, the number of Focus pulses is counted from the detection. Then, when the count number reaches the number of Focus pulses called out from the memory first, stop control of the lens groups 51 and 52 is performed.
[0059]
In fact, since the influence of the inertia of the optical system drive motor 17 and the like is present, if it is not necessary to consider the backlash, the brake control of the optical system drive motor 17 is performed a little before The lens groups 51 and 52 are stopped when the number of Focus pulses is reached. Thereafter, the CPU 11 controls the imaging in response to the full-press of the release switch SW21a.
[0060]
When the imaging control ends, the CPU 11 resets the lens groups 51 and 52 to the original standby position P2. Here, the absolute position signal is detected again to confirm whether or not the lens groups 51 and 52 have returned to the standby position P2.
[0061]
Here, a mechanism for changing the angle of view of the optical viewfinder 25 using the optical system drive motor 17 will be described. FIG. 5 is a schematic configuration diagram showing a mechanism for driving the taking lens and the lens group of the optical viewfinder 25 in the camera of the present embodiment.
[0062]
As shown in FIG. 5, a gear 62 meshes with an output pinion gear (sun gear) 17a of the optical system drive motor 17. The gear 62 meshes with a cam cylinder gear 57a formed on the peripheral surface of the cam cylinder 57 and meshes with a gear train 63. The gear train 63 meshes with a cam gear 72a of the finder zoom cam 72, and these It is communicatively connected. Cam grooves 72b and 72c are formed on the peripheral surface of the finder zoom cam 72. A first finder lens group 73 and a second finder lens group 74 are engaged with the cam grooves 72b and 72c, respectively. It is movable in the optical axis direction.
[0063]
The cam gear 72a and the finder zoom cam 72 are connected via an electromagnetic clutch mechanism 72d, and the electromagnetic clutch mechanism 72d transmits power for integrally rotating the cam gear 72a and the finder zoom cam 72 according to a signal from the CPU 11. The state is switched to one of a state and a power non-transmission state in which the finder zoom cam 72 is not rotated even when the cam gear 72a rotates.
[0064]
Here, when the zoom operation is performed under the control of the CPU 11, the power from the gear 62 is transmitted to the cam cylinder 57 and the finder zoom cam 72 by the electromagnetic clutch mechanism 72d being in the power transmission state. That is, the lens groups 51 and 52 are driven via the cam cylinder 57 in accordance with the cam diagram shown in FIG. 4, and the finder lens groups 73 and 74 are driven via the finder zoom cam 72.
[0065]
In such a case, the zoom magnification of the lens unit 1 and the zoom magnification of the optical finder 25 always change while being changed by the rotation of the optical system drive motor 17. That is, the optical finder 25 has a zoom function. The shapes of the cam cylinder 57 and the finder zoom cam 72 and the number of teeth of each gear of the transmission mechanism 60 are set to appropriate values in view of this operation.
[0066]
On the other hand, when the focusing operation is performed, the power from the gear 62 is transmitted only to the cam cylinder 57 and the finder zoom cam 72 does not rotate because the electromagnetic clutch mechanism 72d is in the power non-transmission state. In such a case, the lens groups 51 and 52 can be driven for the focusing operation via the cam barrel 57, but the first finder lens group 73 and the second finder lens group 74 do not move in the optical axis direction, and accordingly. Even if the photographer is looking into the optical viewfinder 25. There is no discomfort. It should be noted that the present invention is not limited to the above-described embodiment, and it is also possible to apply a cam shape as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-80291.
[0067]
FIG. 6 is a flowchart illustrating a photographing process performed by the digital still camera 100 to which the present invention is applied. In the present embodiment, a focusing operation is performed by a so-called image plane AF. First, in step S101 of FIG. 6, if the power switch (not shown) is turned on, the CPU 11 sets the image display mode in step S102 on the assumption that the shooting mode is set. (It can be set by the photographer operating the operation SW 21). If it is determined that the image display mode has been set, then in step S103, regardless of the operation of the release switch 21a, an image signal is captured via the CCD 3 to perform image processing to obtain image data, and based on that, in step S104. The image is displayed on the image display unit 8 (through image display).
[0068]
Further, in step S105, the CPU 11 determines whether or not a pressing signal (S1 signal) of the first-stage release switch 21a has been input. Here, if it is determined that the pressing signal (S1 signal) of the first-stage release switch 21a is not input, the CPU 11 determines in step S106 whether the zoom switch ST is further turned on. If it is determined that the zoom switch ST has not been turned on, the CPU 11 returns the flow to step S103. Therefore, the CPU 11 newly acquires an image signal via the CCD 3 and performs image processing to obtain image data. The image can be displayed on the image display unit 8. The time for executing this loop is about 1/30 second, that is, unless the photographer operates the release switch 21a and the zoom switch ST, the image display is updated at an interval of about 1/30 second as a predetermined timing. It will be.
[0069]
On the other hand, if it is determined in step S106 that the zoom switch ST has been turned on, the CPU 11 performs driving for a zoom operation in step S107 as described above (the first lens which is a lens group of the photographing optical system). The group 51 and the second lens group 52 are relatively moved so that the distance between them in the optical axis direction changes. Even during such a zoom operation, in step S108, a new image signal is taken in via the CCD 3, image processing is performed, and image data is obtained. In step S109, an image whose angle of view changes is displayed on the image display unit 8. It is displayed continuously. Thus, the zoom drive and the through image display are continued until the zoom switch ST is turned off. In step S110, the CPU 11 determines whether the current zoom operation is from the wide side to the tele side based on a signal from the motor drive circuit 18.
[0070]
If it is determined that the current zoom operation is from the wide side to the tele side, the backlash of the drive system (17a, 62 in FIG. 3) can be neglected. Therefore, in step S111, the CPU 11 turns off the zoom switch ST. If it is determined that the image data has been received, the flow immediately returns to step S103. Therefore, a new image signal is fetched via the CCD 3, image processing is performed to obtain image data, and based on the image data, an image is displayed on the image display unit 8 in step S104. It has become. That is, the through image display is performed without interruption. Note that, when the zoom switch ST is turned off, for example, when moving from the wide side to the tele side, the specified stop position of any of MIDDLE1, MIDDLE2, MIDDLE3, and TELE in FIG. Then, the lens groups 51 and 52 stop.
[0071]
On the other hand, if it is determined in step S110 that the current zoom operation is from the wide side to the tele side, the backlash of the drive system (17a, 62 in FIG. 3) cannot be ignored. Therefore, in the subsequent step S112, if the CPU 11 determines that the zoom switch ST has not been turned off, the CPU 11 returns the flow to step S107, and if it determines that the zoom switch ST has been turned off, the CPU 11 performs backlash removal processing in step S113.
[0072]
The backlash removal processing will be described. FIG. 7 is a diagram showing the rotation position of the motor on the vertical axis and time on the horizontal axis. For example, assuming that zoom driving is performed from the tele side to the wide side from time t0, the CPU 11 turns off the zoom switch ST by releasing the finger from the zoom switch ST between times t0 and t1. It is determined that the operation of the zoom switch ST has been interrupted, and it is determined that the optical system drive motor 17 (FIG. 1) is stopped at the closest specified position Mx.
[0073]
However, since the backlash of the drive system must be eliminated as described above, the CPU 11 drives the optical system drive motor 17 to rotate (overshoot) from the position Mx to the position My on the wide side. Let it. Thereafter, the optical system drive motor 17 is reversed to return to the position of Mx. Thereby, backlash of the drive system can be eliminated.
[0074]
By the way, from the time t2 to the time t3, the optical system drive motor 17 rotates toward the tele-position side, so that the lens groups 51 and 52 also move toward the tele-side, so that a through image is displayed. Thus, the reduced subject image is enlarged immediately before the end of the zoom operation, and the photographer may feel uncomfortable. Therefore, in the present embodiment, it is assumed that the image is not updated while the backlash removal processing is being performed. In other words, the image displayed on the image display unit 8 during the backlash removal is based on the image signal acquired in the latest step S108, and after the zoom switch ST is turned off (operation interrupted), Until the lash removal processing ends, the display is not updated (freezes). Therefore, even if the lens groups 51 and 52 are driven in the reverse direction due to the backlash removal, the image remains frozen during that time, and even if the photographer visually recognizes the image display unit 8, the user does not feel discomfort. Absent.
[0075]
When the backlash elimination processing is completed, the CPU 11 returns the flow to step S103. Therefore, the CPU 11 newly acquires an image signal through the CCD 3, performs image processing to obtain image data, and performs image display based on the image data in step S104. An image is displayed on the unit 8. That is, the update of the through image display is restarted. The timing of freezing the image (the shooting angle of view A obtained at the position of the lens group at the time of freeze) is determined by the timing of restarting the update (the shooting angle of view B obtained at the position of the lens group at the time of restart (the specified position)) (A ≒ B), the sense of discomfort of the photographer is further reduced.
[0076]
When the composition of the subject is determined by performing the zoom drive to a desired position, the photographer can operate the release switch 21a to perform photographing. Accordingly, in step S105, if the CPU 11 determines that the pressing signal (S1 signal) of the first-stage release switch 21a has been input, in step S114, the CPU 11 determines an appropriate exposure condition by performing AE processing. In S115, the control waits for the input of the pressing signal (S2 signal) of the second-stage release switch 21a. If it is determined that the pressing signal (S2 signal) of the second-stage release switch 21a has been input, the CPU 11 performs focusing driving in step S116.
[0077]
The focusing drive at this time is performed by the AE / AF processing circuit 13 while moving the second lens group 52 of the lens unit 1 stepwise while comparing and processing a plurality of image data output from the CCD 3. This is performed by obtaining the focal position. Therefore, at the time of focusing drive, the angle of view of the subject image displayed on the image display unit 8 varies. For example, even in a single-lens reflex camera, the image in the viewfinder can be visually recognized immediately after the release. It may disappear, and the photographer may feel that this is an operation indicating that the release has been performed, and there is an advantage that the photographer does not particularly feel uncomfortable. Note that if the digital still camera 100 includes a so-called active distance measuring device or the like as a distance measuring unit, the focusing drive may be performed based on the output (information on the in-focus position).
[0078]
Thereafter, in step S117, the CPU 11 captures the image signal via the CCD 3 and performs image processing to obtain image data. Based on the image data, the CPU 11 records the image data in the image storage memory 9 in step S118. . Here, the CPU 11 causes the image display unit 8 to display an image as a so-called post image based on the image data (ie, new image data) recorded in the image storage memory 9 in step S119. . Thereafter, the flow returns to step S101.
[0079]
On the other hand, if the image display mode is not set, an image that makes the photographer feel uncomfortable is not displayed on the image display unit 8, and the following processing may be performed. That is, if it is determined in step S102 that the image display mode is not set, the CPU 11 determines in step S120 whether or not the zoom switch ST is turned on. If it is determined that the zoom switch ST has been turned on, the CPU 11 continues the driving for the zoom operation in steps S121 and S122 until the zoom switch ST is turned off in the above-described manner (however, to the wide side). In the case of forward zoom drive, backlash removal shown in FIG. 7 is performed), and if it is determined that the zoom switch ST is not turned on, a step S123 waits for a press signal (S1 signal) of the first-stage release switch 21a. .
[0080]
If it is determined that the depression signal (S1 signal) of the first-stage release switch 21a has been input, an appropriate exposure condition is determined in step S124 by performing AE processing. In step S125, the second-stage release switch 21a is determined. Wait for the pressing signal (S2 signal) to be input. If it is determined that the pressing signal (S2 signal) of the second-stage release switch 21a has been input, the CPU 11 performs focusing driving in step S126, and captures an image signal via the CCD 3 in step S127 to perform image processing. The image data is acquired, and based on the acquired image data, the image data is recorded in the image storage memory 9 in step S128. Thereafter, the flow returns to step S101.
[0081]
FIG. 8 is a flowchart illustrating a photographing process performed by the digital still camera 100 according to the second embodiment. Also in this modification, a focusing operation is performed by a so-called image plane AF, and only different points from the flowchart shown in FIG. 6 will be described.
[0082]
If it is determined in step S110 that the current zoom operation is from the wide side to the telephoto side, then in step S112, the CPU 11 determines whether the zoom switch ST is turned off. If it is determined that the camera has been turned off, in step S113A, the CPU 11 suspends the display of the through image and outputs the image based on the image signal stored in a non-volatile memory (not shown) separate from the memory 8 in advance. An image different from the subject image such as a background color or wallpaper is displayed on the display unit 8. Thereafter, in step S113B, the above-described backlash removal processing is performed.
[0083]
When the backlash removal is completed, the CPU 11 returns the flow to step S103. Therefore, a new image signal is taken in through the CCD 3, image processing is performed, and image data is obtained. 8, an image is displayed. That is, the live view display is restarted.
[0084]
As described above, the present invention has been described with reference to the embodiments. However, the present invention should not be construed as being limited to the above embodiments, and it is needless to say that modifications and improvements can be made as appropriate. For example, the present invention can be applied not only to a digital camera of a step zoom type, but also to a digital camera having a zoom driving motor and a focusing driving motor separately.
[0085]
【The invention's effect】
According to the present invention, it is possible to provide a digital camera having a high function and an inexpensive configuration without giving a photographer an uncomfortable feeling.
[Brief description of the drawings]
FIG. 1 is an external view showing an embodiment of a digital still camera 100 which is an example of a camera to which the present invention is applied. FIG. 1A is a front perspective view of a digital still camera 100, and FIG. Is a rear perspective view.
FIG. 2 is a block diagram showing a functional configuration of the digital still camera 100.
FIG. 3 is a schematic configuration diagram illustrating a lens barrel of the camera according to the present embodiment and a driving configuration thereof.
FIG. 4 is a cam diagram for achieving a zoom operation and a focus operation in the present embodiment.
FIG. 5 is a schematic configuration diagram showing a mechanism for driving a photographing lens and a lens group of an optical finder 25 in the camera of the present embodiment.
FIG. 6 is a flowchart illustrating a photographing process performed by the digital still camera 100 to which the present invention has been applied.
FIG. 7 is a diagram for explaining backlash removal processing.
FIG. 8 is a flowchart illustrating a photographing process performed by the digital still camera 100 according to the second embodiment.
[Explanation of symbols]
8 Image display section
11 CPU
17 Optical system drive motor
100 Digital Still Camera
51 First lens group of lens unit
52 Second lens group of lens unit

Claims (12)

A shooting optical system having a plurality of lens groups;
An image sensor that receives an optical image formed through the imaging optical system and outputs an image signal;
A display unit that displays an image while updating at a predetermined timing based on an image signal output from the image sensor,
Driving means for moving the lens group of the photographing optical system in the optical axis direction and performing driving for a zoom operation,
A zoom switch for causing the driving unit to perform driving for a zoom operation;
Control means for interrupting updating of image display on the display unit in response to interruption of operation of the zoom switch. 2. The digital camera according to claim 1, wherein the driving unit drives the lens group in the reverse direction at least once and then stops the driving in response to the interruption of the operation of the zoom switch. 3. The digital camera according to claim 1, wherein a stop position of the lens group is determined in advance. 4. The digital camera according to claim 1, wherein the control unit restarts updating the image display on the display unit after the lens group stops. 5. The control unit interrupts the updating of the image display on the display unit in response to the interruption of the operation of the zoom switch only when the driving unit performs the driving for the zoom operation in a specific direction. The digital camera according to claim 1, wherein: The driving unit moves a lens group of the imaging optical system in the optical axis direction by power from a single driving source, and performs driving for a focusing operation and driving for a zoom operation. The digital camera according to any one of claims 1 to 5, wherein A shooting optical system having a plurality of lens groups;
An image sensor that receives an optical image formed through the imaging optical system and outputs an image signal;
A display unit that displays an image while updating at a predetermined timing based on an image signal output from the image sensor,
Driving means for moving the lens group of the photographing optical system in the optical axis direction and performing driving for a zoom operation,
A zoom switch for causing the driving unit to perform driving for a zoom operation;
Control means for displaying, on the display unit, an image different from the image displayed when the operation of the zoom switch is continued, in response to the interruption of the operation of the zoom switch. camera. 8. The digital camera according to claim 7, wherein the driving unit drives the lens group in the reverse direction at least once and stops the driving in response to the interruption of the operation of the zoom switch. The digital camera according to claim 7, wherein a stop position of the lens group is determined in advance. The digital camera according to claim 7, wherein the control unit restarts updating the image display on the display unit after the lens group stops. The control unit interrupts the updating of the image display on the display unit in response to the interruption of the operation of the zoom switch only when the driving unit performs the driving for the zoom operation in a specific direction. The digital camera according to claim 7, wherein: The driving unit moves a lens group of the imaging optical system in the optical axis direction by power from a single driving source, and performs driving for a focusing operation and driving for a zoom operation. The digital camera according to any one of claims 7 to 11, wherein

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