JP3794588B2 - camera - Google Patents

Description

  The present invention relates to a camera, and more particularly to a video camera having a zoom lens and an autofocus device.

  An autofocus device for a video camera extracts a high-frequency component of an image signal obtained via a photographing optical system and an image sensor such as a CCD, and evaluates to evaluate an in-focus state by integrating and averaging the extracted high-frequency components. A value is obtained, and the focus lens is driven and controlled to adjust the focus so that the evaluation value takes the maximum value.

  This method has many merits such that the image signal of the photographing screen can be used and the configuration of the lens and the like is simplified.

  However, if the shooting scene changes and the subject distance changes drastically, the focus direction (front focus or rear focus) will not be known, so it will not be possible to handle sudden changes in the subject distance, and the focus will be out of focus. It may take some time before

  The present invention has been made in view of such circumstances, and provides a camera capable of appropriately using these modes by providing a mode in which the focus is not easily blurred in addition to a mode for performing normal focus adjustment by an autofocus device. For the purpose.

In order to achieve the object, a camera according to claim 1 includes a zoom lens, an image sensor on which a subject image is formed via the zoom lens, and an image signal obtained via the zoom lens and the image sensor. Auto focus means for adjusting the focus by moving the focus lens in the zoom lens so that the integral average value of the high frequency component is maximized, and the change range of the focal length of the zoom lens to be equal to or less than a predetermined zoom magnification. Zoom limiting means for limiting the focus lens, and when the focal length change range of the zoom lens is limited by the zoom limiting means, the focus limiting means for limiting the driving range of the focus lens by the autofocus means , From the focus lens drive range over the entire shooting distance range from close to infinity at the zoom position And a focus limiting means for limiting to a narrow range, the autofocus unit, the driving range of the focus lens is limited by the focus limiting means, as characterized by switching the driving speed of the focus lens at low speed Yes.

According to a second aspect of the present invention, there is provided a zoom lens, an imaging element on which a subject image is formed via the zoom lens, and an integral average value of high frequency components of an image signal obtained via the zoom lens and the imaging element. An autofocus unit that adjusts the focus by moving the focus lens in the zoom lens so as to be maximized, and a zoom limiting unit that limits a change range of the focal length of the zoom lens to be equal to or less than a predetermined zoom magnification. When the range of change of the focal length of the zoom lens is limited by the zoom limiting unit, the focus limiting unit limits the driving range of the focus lens by the autofocus unit , and is close to infinity at each zoom position. Focus is limited to a range narrower than the focus lens drive range over the entire shooting distance It includes a scum limiting means, wherein the automatic focusing means, characterized for each of the range of change in focal length of the zoom lens is limited or restricted is released by the zoom limiting means, to perform a restart of the focus adjustment It is said.

  According to a third aspect of the present invention, in the camera according to the first or second aspect, the zoom lens performs the correction of the image formation position and the focus adjustment by the magnification change of the subject image by the variator lens, and the focus limiting unit. Is characterized in that it is limited within a certain movement range from the position of the focus lens set in advance at each zoom position when the subject distance is infinity.

  According to a fourth aspect of the present invention, in the camera according to the first or second aspect, the zoom lens performs image position correction and focus adjustment by changing a subject image by a variator lens, and the focus lens. Includes a pulse motor for driving the focus lens, and the focus limiting means is configured to keep the number of pulses applied to the pulse motor from a preset focus lens position at each zoom position when the subject distance is infinity. It is characterized by limiting to within the value.

  According to the present invention, the zoom limit means limits the change range of the focal length of the zoom lens to a predetermined zoom magnification or less, and the focus limit means limits the drive range of the focus lens by the autofocus means. . In other words, if the change range of the focal length of the zoom lens is limited, the focus is less likely to be out of focus, and if the drive range of the focus lens is limited so as to cover a predetermined shooting distance range, autofocus is stabilized. Therefore, when the subject to be photographed is limited to a certain extent and a subject within a predetermined photographing distance range is photographed, the above restriction makes it possible for the focus to hardly be blurred even if there is a sudden change in the subject distance. Or, even if the focus is slightly blurred, the focus can be immediately adjusted by the autofocus means.

  When the focus lens drive range is limited, the focus lens drive speed is switched to a low speed, thereby further stabilizing the autofocus.

  Note that when using an optical viewfinder, it is not possible to check out-of-focus, so auto focus is stable and there is no blur. However, by applying the above restrictions, the optical viewfinder Will be able to use.

  According to the present invention, in addition to the mode in which the normal focus adjustment is performed by the autofocus device, the mode in which the focus is difficult to blur is provided. Therefore, the optical finder can be used according to the mode. In other words, when using an optical viewfinder, it is not possible to check out-of-focus, so it is necessary that the autofocus is stable and there is no blur. Will be able to use.

  A preferred embodiment of a camera according to the present invention will be described in detail below with reference to the accompanying drawings.

  1 and 2 are perspective views of the camera according to the present invention as seen from the front side and the back side, respectively. FIG. 3 is a plan view of the camera, and shows a state in which the liquid crystal monitor is opened.

  This camera is a camera-integrated VTR and has a substantially rectangular parallelepiped external shape that is thin in the front-rear direction of the camera (the direction of arrow AB in FIG. 1). As shown in FIG. 1, the zoom lens 10, the optical finder 12, and the stereo microphone 14 are provided at the top of the camera body. A liquid crystal monitor 16 is disposed at the top of the camera body so as to be freely opened and closed. Reference numeral 18 denotes a VTR deck portion to which an 8 mm cassette is attached and detached, 20 denotes a side grip portion, and 22 denotes a photographing button.

  The zoom lens 10 is, for example, a 10 × zoom zoom lens having a focal length of 3.3 mm to 33 mm, and the focal length is continuously varied electrically by operating the zoom button 24 (see FIG. 2).

  The optical finder 12 is, for example, a zoom finder for 3 × zoom, and at least in the range in which the focal length can be adjusted, the focal point of the optical finder 12 changes according to the change in the focal length of the zoom lens 10 so that the photographing range and the visual field range coincide. The distance is adjusted. The details of the zoom lens 10 and the optical viewfinder 12 will be described later.

  The VTR deck unit 18 includes a rotating head drum, a tape loading mechanism, a tape feeding mechanism, and the like (not shown), and a video signal indicating a subject photographed by the zoom lens 10 and an audio signal detected by the stereo microphone 14 are stored in an 8 mm cassette. Magnetic recording and playback on videotape. Reference numeral 26 denotes a cassette lid that is opened and closed when the cassette is inserted and removed.

The side grip portion 20 is formed in a shape that can be gripped with the right hand, a finger hook portion 30 is formed on the front surface of the camera, and a concave portion 32 in which the thumb and the base portion of the thumb are located as shown in FIG. Is formed.
The shooting button 22 is disposed on the front side of the camera and is operated by the index finger of the right hand that holds the side grip portion 20. The zoom button 24 is arranged at a position where it can be operated with the thumb of the right hand.

  On the other hand, as shown in FIG. 2, a liquid crystal display unit 34 is disposed on the rear surface of the camera adjacent to the lower side of the eye cup of the optical viewfinder 12, and a battery 36 is mounted below the liquid crystal display unit 34. . Further, a monitor open / close button 38, a power switch 40, a remote control light receiving unit 42, and the like are provided. Further, a diopter adjustment knob 44, a battery eject button 46, and a cassette eject button 48 are provided on the side of the camera body.

  By the way, the liquid crystal monitor 16 functions as a monitor at the time of image reproduction and also functions as a finder at the time of photographing. The liquid crystal monitor 16 is disposed so as to be openable and closable and electrically connected to the camera body via a hinge portion 16A. It is formed so as to be flush with each surface of the camera body when closed.

  When the liquid crystal monitor 16 is opened, the operation panel 50 provided at the top of the camera body is exposed as shown in FIG. 3, and various buttons can be operated. Note that 52 is a shooting button (double / single) switch, 54 is a negative film (off / on) switch, 56 is a sport mode (off / on) switch, 58 is a monitor (off / on) switch, and 60 is brightness. An adjustment knob, 62 is a volume control knob, 64 is a speaker, 66 is a mode switching button for switching between camera mode and VTR mode, and 68 is a group of buttons for commanding playback, stop, fast forward, rewind, etc. in the VTR mode. is there. Reference numeral 70 denotes a lock hole into which the lock claw 16B on the liquid crystal monitor side is inserted.

  Next, the zoom lens 10 and the optical viewfinder 12 will be described in detail. As shown in FIG. 4, the zoom lens 10 mainly includes a front lens (fixed lens) 100, a variator lens 102, fixed lenses 104 and 108, and a focus lens 106. The variator lens 102 and the focus lens 106 are respectively guides. The rod 110 is guided so as to be movable in the optical axis direction.

  The variator lens 102 is driven in the optical axis direction by the driving force transmitted from the zoom motor 112 via the gears 114 and 116 and the zoom cam 118, and the focus lens 106 is transmitted from the focus motor 120 via the lead screw 122 and the nut 124. It is driven in the optical axis direction by the applied driving force.

  The zoom motor 112 is driven forward or backward in accordance with the operation of the zoom button 24. That is, as shown in FIG. 6, when a signal indicating the tele direction or the wide direction is input from the zoom button 24 to the camera control microcomputer 130, the camera control microcomputer 130 sends the zoom signal to the zoom motor via the zoom driver 132. The zoom motor 112 is driven forward or reversely. By driving the zoom motor 112, the variator lens 102 moves forward or backward in the optical axis direction. The position (zoom position) of the variator lens 102 is detected by the zoom encoder 134, and the zoom position (focal length of 3.3 mm to 33 mm) is applied to the camera control microcomputer 130 as an 8-bit signal of 0 to 255. (See FIG. 7).

  On the other hand, the focus motor 120 is driven according to the position (zoom position) of the variator lens 102 and the subject distance. In other words, the focus lens 106 is driven so that the subject image scaled by the variator lens 102 is formed on an imaging element 140 (hereinafter referred to as CCD) 140 such as a CCD, and a lens that forms the best image by the contrast method. Driven to position.

  Here, the control of the focus lens 106 will be described in detail.

  First, the position of the focus lens 106 can be detected by the output of the home position sensor 136 that detects the home position of the focus lens 106 and the number of pulses to the focus motor (pulse motor) 120. In other words, the home position sensor 136 is necessary for the focus lens 106 to form a subject image on the CCD 140 when the subject distance is infinite and the variator lens 102 is at the wide end. When the focus lens 106 is reached, a detection signal is output to the camera control microcomputer 130. The camera control microcomputer 130 counts the number of pulse signals output to the focus motor 120 via the focus driver 134 with reference to the position where the detection signal is input from the home position sensor 136, and the focus lens 106 based on the count value. The position of is detected. As shown in FIG. 7, the count value of pulses given to the focus motor 120 is from the home position (number of pulses = 0) to 340 pulses.

Further, as shown in FIG. 7 , the camera control microcomputer 130 determines the position (number of pulses) of the focus lens 106 with respect to each zoom position (position represented by 0 to 255) for each subject distance of infinity, 1 m, and 10 mm. The focus lens 106 is controlled so as to be a required position corresponding to the position (zoom position) of the variator lens 102 using this look-up table.

That is, when the focus lens 106 is stopped at the solid line (curve indicating infinity) in FIG. 7 by autofocus, which will be described later, and then zooming is performed, the focus lens 106 is controlled to move on the solid line. Is done. Similarly, when zooming is performed in a state where it is stopped at the alternate long and short dash line (curve indicating 1 m), the focus lens 106 is controlled to move on the alternate long and short dash line, and is stopped at the dotted line (curve indicating 10 mm). When zooming is performed in a state in which the focus lens 106 is in position, the focus lens 106 is controlled to move on the dotted line. When the focus lens 106 is at a position other than the curve, the focus lens 106 is controlled so as to trace on a curve where the ratio between the position and each curve is constant.
The control of the focus lens 106 during zooming has been described above. Next, the control of the focus lens 106 when performing focus adjustment will be described.

  The subject light imaged on the light receiving surface of the CCD 140 via the zoom lens 10 is accumulated for a predetermined time by each sensor and converted into a signal charge of an amount corresponding to the intensity of the light. The signal charges accumulated in this way are read out to the shift register by a read gate pulse of a predetermined period applied from a CCD driving circuit (not shown), and sequentially read out as an image signal by a register transfer pulse.

  The image signal read out from the CCD 140 in this way is converted into a 10-bit digital image signal via the AGC circuit 142 and the A / D converter 144, and then the liquid crystal monitor 16 via a signal processing circuit (not shown). Are output to the VTR deck unit 18 and are also output to the high pass filter unit 148 and the photometry unit 150 via the bit compression unit 146 that performs nonlinear compression to 8 bits.

  The high pass filter unit 148 extracts a high frequency component of the input digital image signal and outputs the high frequency component to the evaluation value calculation unit 152. The evaluation value calculation unit 152 integrates and averages the input signal to obtain an evaluation value for evaluating the in-focus state. The calculated value is output to the camera control microcomputer 130. Then, the camera control microcomputer 130 controls the focus lens 106 so that the input evaluation value is maximized. When the evaluation value becomes maximum in this way, the focus adjustment by the focus lens 106 is finished. When the evaluation value changes more than a certain value, the above-described autofocus is restarted because the scene has changed.

  The photometry unit 150 detects the brightness of the screen from the input digital image signal, and outputs a signal indicating the brightness of the screen to the camera control microcomputer 130. The camera control microcomputer 130 controls the iris 105 via the iris driver 136 and the iris meter 138 so that the brightness of the screen becomes a predetermined brightness. The opening degree of the iris 105 is detected by an iris sensor 139, and a signal indicating the opening degree is applied to the camera control microcomputer 130. If the brightness of the screen cannot be controlled by the iris 105, the camera control microcomputer 130 outputs a control signal to the AGC circuit 142 to control the gain of the image signal.

  Next, the optical finder 12 will be described.

  As shown in FIG. 5, the optical viewfinder 12 mainly includes an objective lens 160 facing the subject, a front zoom lens 162 and a rear zoom lens 164 that change the focal length, an appropriate fixed lens 166, and an eyepiece lens 168. These lenses are arranged inside a substantially L-shaped finder tube 170.

  The objective lens 160 is fixed to the tip of the finder cylinder 170. The front zoom lens 162 is held by the mount portion 172A of the front lens frame 172 behind the objective lens 160, and the rear zoom lens 164 is held by the mount portion 174A of the rear lens frame 174 behind the objective lens 160.

  A guide bar 176 is provided on the side of the front zoom lens 162 and the rear zoom lens 164 substantially in parallel with the direction of the optical axis S. The guide bar 176 is supported by the side wall of the finder cylinder 170. . The lens frames 172 and 174 are constructed by integrally connecting slide cylinders 172B and 174B to the side portions of the mount parts 172A and 174A. Yes. Further, guide protrusions 172C and 174C are formed on the side portions of the mount portions 172A and 174A, and are engaged with guide holes 170A formed in the side wall of the finder cylinder. Note that engagement protrusions 172D and 174D are provided as protrusions on the sliding cylinders 172B and 174B. Further, the sliding cylinders 172B and 174B are connected to each other and a tension spring 178 is stretched, and the lens frames 172 and 174 are urged toward each other.

  On the other hand, a cam shaft 180 that is substantially parallel to the guide rod 176 is provided adjacent to the guide rod 176, and the cam shaft 180 is rotatably supported on the side wall of the finder cylinder 170. The cam shaft 180 is fitted with a substantially cylindrical zoom cam 182, and cam surfaces 182 </ b> A are formed at both ends of the zoom cam 182. Engaging protrusions 172D and 174D of the lens frames 172 and 174 are in contact with the cam surface 182A, and the engaging protrusions 172D and 174D are guided along the cam surface 182A. Here, when the zoom cam 182 further rotates beyond the maximum magnification so that the focal length is changed while maintaining the predetermined optical relationship between the front zoom lens 162 and the rear zoom lens 164, the maximum The cam surface 172A is formed so as to maintain the magnification (see FIG. 4).

  One end of the cam shaft 180 protrudes to the outside of the finder cylinder 170, and a gear 184 is fitted therein. The gear 184 is linked to the rotation shaft of the zoom motor 112 via gears 114 and 116 as shown in FIG. For this reason, as will be described later, the change in the focal length of the optical viewfinder 12 and the change in the focal length of the zoom lens 10 are substantially matched up to 3 × zoom.

  On the other hand, a field frame plate 186 is disposed behind the rear zoom lens 164, and a reflecting mirror 188 that bends the optical axis S is provided at a corner of the finder tube 170. The fixed lens 166 is disposed on the side of the reflecting mirror 188, and a finder shutter 190 is disposed at an appropriate position.

  The finder shutter 190 is composed of a substantially flat shutter plate 192, and a rotating shaft 192A is formed at the upper end side of the shutter plate 192. The rotation shaft 192A is rotatably supported by a notch 170B on the side wall of the finder tube 170, and one end of the rotation shaft 192A protrudes outside the finder tube 170 to form a lever portion 192B. Yes. That is, the shutter plate 192 is substantially perpendicular to the optical axis S and blocks the optical path to close the shutter, and the shutter plate 192 jumps up substantially parallel to the optical axis S to release the blocking of the optical path. It can be freely rotated in the open state. The rotating shaft 192A is provided with a return spring 194 that is a winding spring, and biases the shutter plate 192 in the closing direction.

  The lower end portion 196A of the lever 196 is engaged with the lever portion 192B, and the upper end portion 196B of the lever 196 is pressed in the direction indicated by the arrow A by the lock claw 16B of the liquid crystal monitor 16. . Therefore, when the liquid crystal monitor 16 is closed, the lever 196 rotates counterclockwise around the support shaft 196C in FIG. 5 to jump up and open the shutter plate 192 against the spring biasing force. On the other hand, when the liquid crystal monitor 16 is opened, the shutter plate 192 is closed by the urging force of the return spring 194.

  Further, a mode changeover switch 198 is provided opposite to the upper end 196B of the lever 196, and is turned on / off in accordance with the opening / closing of the liquid crystal monitor 16 as described above. The mode changeover switch 198 is a switch for selecting one of a normal mode using the liquid crystal monitor 16 and an optical finder mode using the optical finder 12, and when the liquid crystal monitor 16 is opened. When the liquid crystal monitor 16 is closed, the optical finder mode is set.

In accordance with these modes, the electrical circuit connected to the control device of the camera body is intermittently connected. That is, the liquid crystal monitor is turned on in the normal mode, and the liquid crystal monitor is turned off in the optical viewfinder mode. Therefore, the optical viewfinder mode is a power saving mode, and is also a pan focus mode in which it is difficult to blur as will be described later.
In this embodiment, the viewfinder shutter 190 is mechanically opened and closed in accordance with the opening and closing operation of the liquid crystal monitor 16, but the motor or the like is operated by the mode changeover switch 198 or other switch appropriately operated by the photographer. The finder shutter may be opened and closed by driving the finder shutter.

  A prism 199 that bends the optical axis S substantially at a right angle is accommodated in the base end portion of the finder tube 170. The eyepiece lens 168 is disposed so as to face the exit surface of the prism 199. Furthermore, a dead space is formed by the L-shaped finder cylinder 170. Since the dead space is provided with the stereo microphone 14, the switch board (not shown) of the operation panel unit 50, etc., the space. Is being used effectively.

  Next, the limitation on the change range of the focal length of the zoom lens 10 and the limitation on the driving range of the focus lens 106 according to the switching between the normal mode and the optical finder mode will be described.

  The variable focus lens device of the zoom lens 10 is a 10 × zoom, and the liquid crystal monitor 16 can confirm images of all focal lengths in the change range, whereas the variable focus of the optical finder 12 can be confirmed. Since the lens apparatus has a 3 × zoom, it is impossible to capture images of all focal lengths of the zoom lens 10 with substantially the same angle of view.

  Therefore, the change range of the focal length of the zoom lens 10 can be varied from 0 to 255 as shown in FIG. 7, but when the mode is switched to the optical finder mode, the focal length is reduced to 24-162 and the optical finder 12 is changed. Set to the focal length change range. That is, when the camera control microcomputer 130 is switched to the optical finder mode by the mode changeover switch 198, the lens moving mechanism of the zoom lens 10 is limited as described above.

  In the normal mode, when the zoom lens 10 is driven beyond 3 × zoom, the engaging protrusions 172D and 174D of the lens frames 172 and 174 of the optical viewfinder 12 are formed on the cam surface 182A of the zoom cam 182. Thus, even when the zoom cam 182 rotates, the front zoom lens 162 and the rear zoom lens 164 are stationary in the 3x zoom state. Then, when the zoom lens 10 is in a state exceeding 3 × zoom when the normal mode is switched to the optical finder mode, the zoom lens 10 is immediately returned to 3 × zoom, and the optical finder is displayed. It is matched with 12 magnifications.

  Incidentally, the drive range for focus adjustment of the focus lens 106 becomes smaller as the zoom lens 10 becomes lower in magnification as shown in FIG. Therefore, if the change range of the focal length of the zoom lens 10 is limited as described above, the driving range for focus adjustment of the focus lens 106 can be reduced, and the photographing distance is in a range of 1 m to infinity, for example. In some cases, the drive range for focus adjustment of the focus lens 106 is further reduced, and the drive range of the focus lens 106 is about 10 pulses as the number of drive pulses to the focus motor 120 even in the case of 3 × zoom. .

  Therefore, when the mode is switched to the optical finder mode and the change range of the focal length of the zoom lens 10 is limited, the drive range of the focus lens 106 is also limited to a certain range as shown by the hatched lines in FIG. This range is a range in which the number of pulses applied to the focus motor 120 from the position of the focus lens 106 at infinity is within 10 pulses.

  By limiting the drive range of the focus lens 106 in this way, an optical viewfinder is used in which the focus is less likely to be blurred when the shooting distance is in the range of 1 m to infinity, and in particular, the focus cannot be confirmed. It is suitable when doing.

  Further, by limiting the drive range of the focus lens 106, autofocus is also stabilized. In other words, since it is difficult to focus, a good focus evaluation value can be obtained during autofocus, and the direction of focus (front focus or rear focus) is not lost, and as a result, focusing is performed quickly. .

  Furthermore, in this embodiment, when the mode is switched to the optical finder mode, the driving speed of the focus lens 106 is also switched to a low speed so that the autofocus is more stable.

  Furthermore, when the normal mode is switched to the optical finder mode, or when the optical finder mode is switched to the normal mode, the autofocus is restarted.

  When photographing a negative film, a negative film photographing device including a close-up lens, a film carrier, a backlight and the like is attached in front of the zoom lens 10, and the negative film switch 54 is turned on. Also in this case, as shown in FIG. 7, the change range of the focal length of the zoom lens 10 is limited.

  The operation of the embodiment of the camera according to the present invention configured as described above will be described below.

  When the photographer turns on the power switch 40 of the camera, the camera is on standby in a state where photographing is possible. The subject image passes through the zoom lens 10 and is captured by the CCD 140. When the mode selector switch 198 is set to the normal mode, that is, when the liquid crystal monitor 16 is in the open position 1 as shown by the solid line as shown in FIG. The photographer can take a picture while checking the image on the liquid crystal monitor 16.

  In this normal mode, the shutter plate 192 is substantially perpendicular to the optical axis S by the urging force of the return spring 194 as described with reference to FIG. Therefore, the optical path of the optical finder 12 is blocked and the finder shutter 190 is closed, and the subject image cannot be confirmed even when the photographer looks into the optical finder 12.

  By the way, when the mode changeover switch 198 is switched to the optical viewfinder mode when the battery capacity is low, the liquid crystal monitor 16 is set to the closed position 2 as shown by the broken line as shown in FIG. The lever 196 is rotated in conjunction with the closing operation of the liquid crystal monitor 16, and the mode switch 198 is switched to the optical finder mode by the lever 196, and the shutter plate 192 is provided with a shutter plate via the lever portion 192B. 192 is flipped up against the urging force of the return spring 46, and the shutter plate 192 is in a state substantially parallel to the optical axis S, so that the optical path is unblocked. Then, the subject image is transmitted through the objective lens 160, the front zoom lens 162, the rear zoom lens 164, the fixed lens 166, the eyepiece lens 168, etc., and is captured by the photographer.

Further, when the mode changeover switch 198 is switched to the optical finder mode, the electric circuit is interrupted and the liquid crystal monitor 16 is turned off. Therefore, the photographer views the subject image only with the optical viewfinder 12.
Here, when the photographer operates the zoom button 24, the zoom motor 112 is driven, and the zoom cam 118 on the zoom lens 10 side and the zoom cam 182 on the optical viewfinder 12 side rotate simultaneously as shown in FIG.

  When the zoom cam 118 on the zoom lens 10 side rotates, the variator lens 102 moves forward and backward to change the subject image, and the focus lens 106 is controlled according to the position (zoom position) of the variator lens 102 so that the focus is not lost. To be.

  Further, when the zoom cam 182 on the optical finder 12 side rotates, the front zoom lens 162 and the rear zoom lens 164 are moved while maintaining a predetermined optical relationship, and the focal length of the optical finder 12 is changed. .

  In this way, the change in the focal length of the zoom lens 10 and the change in the focal length of the optical viewfinder 12 are substantially coincident.

  As described above, in the optical finder mode, the focal length change range of the zoom lens 10 and the drive range for focus adjustment of the focus lens 106 are limited. Further, when the zoom lens 10 is in a state exceeding 3 × zoom when the normal mode is switched to the optical finder mode, the zoom lens 10 is immediately returned to 3 × zoom, and the optical finder is displayed. It is matched with 12 magnifications.

FIG. 1 is a perspective view of a camera according to the present invention as viewed from the front side. FIG. 2 is a perspective view of the camera according to the present invention as seen from the back side. FIG. 3 is a plan view of the camera shown in FIGS. 4 is a partial cross-sectional view of the zoom lens and the optical viewfinder of the camera shown in FIG. FIG. 5 is a perspective view showing the structure of the optical viewfinder of the camera shown in FIG. FIG. 6 is a block diagram of the main part of the camera according to the present invention. FIG. 7 is a graph used to explain the change range of the focal length of the zoom lens and the limitation of the drive range of the focus lens.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Zoom lens, 12 ... Optical finder, 14 ... Stereo microphone, 16 ... Liquid crystal monitor, 16B ... Lock claw, 102 ... Variator lens, 106 ... Focus lens, 112 ... Zoom motor, 118, 182 ... Zoom cam, 120 ... Focus Motor 130, microcomputer for camera control, 140 CCD, 162 front zoom lens, 164 rear zoom lens, 170 finder cylinder, 190 finder shutter, 192 shutter plate, 194 return spring, 196 lever, 198 ... Mode switch

Claims (4)

A zoom lens,
An image sensor on which a subject image is formed via the zoom lens;
Autofocus means for adjusting the focus by moving the focus lens in the zoom lens so that the integral average value of the high-frequency component of the image signal obtained through the zoom lens and the image sensor is maximized;
Zoom limiting means for limiting the change range of the focal length of the zoom lens to be equal to or less than a predetermined zoom magnification;
When the range of change of the focal length of the zoom lens is limited by the zoom limiting unit, the focus limiting unit limits the driving range of the focus lens by the autofocus unit , from close to infinity at each zoom position Focus limiting means for limiting to a range narrower than the drive range of the focus lens over the entire shooting distance range ,
The auto focus means switches the focus lens drive speed to a low speed when the focus lens drive range is restricted by the focus restriction means. A zoom lens,
An image sensor on which a subject image is formed via the zoom lens;
Autofocus means for adjusting the focus by moving the focus lens in the zoom lens so that the integral average value of the high-frequency component of the image signal obtained through the zoom lens and the image sensor is maximized;
Zoom limiting means for limiting the change range of the focal length of the zoom lens to be equal to or less than a predetermined zoom magnification;
When the range of change of the focal length of the zoom lens is limited by the zoom limiting unit, the focus limiting unit limits the driving range of the focus lens by the autofocus unit , from close to infinity at each zoom position Focus limiting means for limiting to a range narrower than the drive range of the focus lens over the entire shooting distance range ,
The auto-focusing unit restarts focus adjustment every time the zoom limiting unit limits or cancels the change range of the focal length of the zoom lens.   The zoom lens performs image position correction and focus adjustment by changing the magnification of a subject image using a variator lens, and the focus limiting unit is set in advance at each zoom position when the subject distance is infinite. 3. The camera according to claim 1, wherein the camera is limited within a certain moving range from the position of the focus lens.   The zoom lens performs image position correction and focus adjustment by changing the magnification of a subject image by a variator lens, and the focus lens includes a pulse motor that drives the focus lens. 3. The camera according to claim 1, wherein the number of pulses applied to the pulse motor from a position of a focus lens set in advance at each zoom position when the subject distance is infinite is limited to a predetermined value or less.

Images