JP2006276464A - Vari-focal lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact vari-focal lens which can be focused at high speed. <P>SOLUTION: A zoom lens 70 is moved in an optical axis direction through a pin 74A by turning a cam ring 68. At such a time, a pin 74B fit in a focus cam 78 provided in the cam ring 68 moves a focus frame 60 in the optical axis direction simultaneously. The movement of the focus frame 60 in a rotating direction is regulated by a shaft 80B, and the focus frame 60 and a focus motor 62 fixed in the focus frame 60 are moved in the optical axis direction by turning the cam ring 68. Thus, the home position of a focus lens 72 is also moved in the optical axis direction, whereby the extending amount of the focus lens 72 required for focusing is made small and time required for focusing is made short. Besides, since a lead screw 66 for moving the focus lens 72 is made short, the entire length of the vari-focal lens 21 is shortened. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable focus lens, and more particularly to a variable focus lens that drives a built-in focus lens with a motor to focus.

  In recent years, so-called AF (autofocus), in which focusing is automatically performed in a digital video camera or digital camera more than a normal silver salt camera, has become a very important and naturally necessary function. A zoom lens that can change the focal length of the photographing lens and change the image magnification is also an extremely important function.

  However, in a zoom lens with a high magnification, the amount of movement of the focus lens from the shortest shooting distance to infinity becomes long, which means that AF takes time, so it is impossible to shoot quickly and miss a photo opportunity There is.

  In addition, if the amount of movement of the focus lens is increased, the lead screw of the focus lens must be lengthened accordingly, which increases the length of the lens and hinders the overall thinning of the camera.

  That is, as shown in FIG. 8, since the focus motor 62 of the lens 121 is fixed to the mount 64 side, even if the photographer moves the zoom lens 70 in the optical axis direction (left-right direction in the figure) and performs zooming, Since the focus frame 60 always starts driving from the same home position, depending on the zoom position, it is necessary to extend a long distance when driving the focus lens 72 to perform focusing. For this reason, the time required for the focusing operation is increased, and as a result, the time required for photographing is increased.

  Further, if it is necessary to extend a long distance when performing focusing, the lead screw 66 for moving the focus frame 60 also needs to be lengthened. Therefore, the total length of the lens 121 is also lengthened, and the entire camera is reduced in size and thickness. Will be hindered.

  In order to shorten the AF time in an interchangeable lens camera such as a single-lens reflex camera, a configuration that includes a plurality of focus detection means such as phase difference detection and contrast detection and performs optimum focus detection according to the situation has been proposed (for example, Patent Document 1).

However, although the focus detection speed is improved in the above configuration, the time required for the focusing operation, that is, the operation of the focus lens is not shortened. The problem has not been resolved.
JP 2003-029135 A

  In consideration of the above-described facts, the present invention has an object to provide a variable focus lens that is compact and can be focused at high speed.

  The variable focal length lens according to claim 1 is a variable focal length lens capable of changing a focal length by moving a part of the optical element in the optical axis direction by rotating a cam ring, and moves in the optical axis direction. And a focus lens for performing a focusing operation, and the home position of the focus lens moves in conjunction with the rotation of the cam ring.

  In the invention having the above-described configuration, the home position of the focus lens can be moved in conjunction with the change in the focal length of the lens, so that the focus lens movement amount during the focusing operation can be reduced, and the variable focus lens capable of focusing at high speed. It can be.

  3. The variable focus lens according to claim 2, wherein the focus lens is extended with a macro area that is one of or both of a tele end of the cam ring and a telephoto side of the cam ring or a wide side of the wide end. The home position of the focus lens moves in conjunction with rotation of the lens.

  In the invention with the above configuration, in a macro region where a large amount of focus lens needs to be extended, the focus lens is extended in conjunction with the rotation of the cam ring, thereby reducing the amount of focus lens movement during macro photography and focusing at high speed. Possible variable focus lens.

  The variable focus lens according to claim 3 is characterized in that the home position of the focus lens moves toward the subject in conjunction with the rotation of the cam ring.

  In the invention with the above configuration, the focus lens home position is extended toward the subject in conjunction with the rotation of the cam ring, thereby reducing the amount of movement of the focus lens during the focusing operation, and a variable focus lens capable of focusing at high speed. be able to.

  Since the present invention has the above-described configuration, it has been possible to obtain a variable focus lens that is small and can be focused at high speed.

<Appearance>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an external configuration of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  FIG. 1 shows a camera according to a first embodiment of the present invention.

  In front of the digital camera 10, a variable focus variable focus lens 21 for forming a subject image on an image sensor, a strobe 44 that emits light to irradiate the subject as necessary during photographing, and a composition of the subject to be photographed And a finder 20 used for determining. Further, on the upper surface of the digital camera 10, a release button (so-called shutter) 56A that is pressed when performing shooting and a power switch 56B are provided.

  Note that the release button 56A of the digital camera 10 according to the present embodiment is pressed down to an intermediate position (hereinafter referred to as “half-pressed state”) and to a final pressed position beyond the intermediate position. A two-stage pressing operation of a state (hereinafter referred to as a “fully pressed state”) can be detected.

  In the digital camera 10, the release button 56A is pressed halfway to activate the AE (Automatic Exposure) function to set the exposure state (shutter speed, aperture state), and then AF (Auto Focus). , Automatic focusing) function is performed to control focusing, and then exposure (photographing) is performed when the button is fully pressed.

  On the other hand, on the back of the digital camera 10, an eyepiece of the above-described finder 20, a liquid crystal display (hereinafter referred to as “LCD”) 38 for displaying a photographed subject image, a menu screen, and the like are photographed. There is provided a mode changeover switch 56C that is slid and operated when setting a shooting mode that is a mode to be performed and a reproduction mode that is a mode for reproducing a subject image on the LCD 38.

  Further, on the back of the digital camera 10, a cross cursor button 56D, a forced light emission switch 56E that is pressed to set a forced light emission mode, which is a mode for forcibly causing the flash 44 to emit light at the time of shooting, and a variable focus lens. A zoom button 56F for zooming 21 to a telephoto / wide angle position is further provided.

  The cross-cursor button 56D has a total of five arrow keys indicating four upward, downward, left, and right directions of movement in the display area of the LCD 38 and a determination key positioned at the center of the four arrow keys. Consists of two keys.

The zoom button 56F can change the focal length of the varifocal lens 21 by pressing one of T (telephoto) / W (wide angle) in a seesaw manner, and can continuously change the magnification of the captured image.
<Electric system>
Next, the configuration of the electrical system of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  The digital camera 10 includes an optical unit 22 configured to include the variable focus lens 21 described above, a charge coupled device (hereinafter referred to as “CCD”) 24 disposed behind the optical axis of the variable focus lens 21, and And an analog signal processing unit 26 that performs various analog signal processing on the input analog signal.

  The digital camera 10 also performs an analog / digital converter (hereinafter referred to as “ADC”) 28 that converts an input analog signal into digital data, and performs various digital signal processing on the input digital data. And a digital signal processing unit 30.

  The digital signal processing unit 30 has a built-in line buffer having a predetermined capacity, and also performs control to directly store the input digital data in a predetermined area of the memory 48 described later.

  The output terminal of the CCD 24 is connected to the input terminal of the analog signal processing unit 26, the output terminal of the analog signal processing unit 26 is connected to the input terminal of the ADC 28, and the output terminal of the ADC 28 is connected to the input terminal of the digital signal processing unit 30. . Accordingly, the analog signal indicating the subject image output from the CCD 24 is subjected to predetermined analog signal processing by the analog signal processing unit 26, converted into digital image data by the ADC 28, and then input to the digital signal processing unit 30.

  On the other hand, the digital camera 10 generates a signal for displaying a subject image, a menu screen or the like on the LCD 38 and supplies the signal to the LCD 38, and a CPU (Central Processing Unit) 40 that controls the operation of the entire digital camera 10. A memory 48 for storing digital image data obtained by photographing, and a memory interface 46 for controlling access to the memory 48 are included.

  Further, the digital camera 10 includes an external memory interface 50 for enabling the portable memory card 52 to be accessed by the digital camera 10, and a compression / decompression processing circuit 54 for performing compression processing and decompression processing on the digital image data. It is configured to include.

  In the digital camera 10 of the present embodiment, a VRAM (Video RAM) is used as the memory 48 and a smart media (Smart Media (registered trademark)) is used as the memory card 52.

  The digital signal processing unit 30, the LCD interface 36, the CPU 40, the memory interface 46, the external memory interface 50, and the compression / decompression processing circuit 54 are connected to each other via a system bus BUS. Therefore, the CPU 40 controls the operation of the digital signal processing unit 30 and the compression / decompression processing circuit 54, displays various information via the LCD interface 36 to the LCD 38, the memory interface 46 to the memory 48 and the memory card 52, and the external memory interface. 50 can be accessed each.

  On the other hand, the digital camera 10 includes a timing generator 32 that mainly generates a timing signal for driving the CCD 24 and supplies the timing signal to the CCD 24, and the driving of the CCD 24 is controlled by the CPU 40 via the timing generator 32.

  Further, the digital camera 10 is provided with a motor drive unit 34, and driving of a focus motor 62, a zoom motor, and an aperture drive motor (not shown) provided in the optical unit 22 is also controlled by the CPU 40 via the motor drive unit 34. The

  Further, the release button 56A, the power switch 56B, the mode changeover switch 56C, the cross cursor button 56D, and the forced light emission switch 56E are connected to the CPU 40, and the CPU 40 can always grasp the operation state of these operation units 56. .

In addition, the digital camera 10 is provided with a charging unit 42 that is interposed between the strobe 44 and the CPU 40 and charges power for causing the strobe 44 to emit light under the control of the CPU 40. Further, the strobe 44 is also connected to the CPU 40, and the light emission of the strobe 44 is controlled by the CPU 40.
<Operation>
Next, the overall operation of the digital camera 10 according to the present embodiment during shooting will be briefly described.

  First, the CCD 24 performs imaging through the optical unit 22 and sequentially outputs analog signals for R (red), G (green), and B (blue) indicating the subject image to the analog signal processing unit 26. The analog signal processing unit 26 performs analog signal processing such as correlated double sampling processing on the analog signal input from the CCD 24 and sequentially outputs the analog signal to the ADC 28.

  The ADC 28 converts the R, G, and B analog signals input from the analog signal processing unit 26 into 12-bit R, G, and B signals (digital image data) and sequentially outputs them to the digital signal processing unit 30. To do. The digital signal processing unit 30 accumulates digital image data sequentially input from the ADC 28 in a built-in line buffer and temporarily stores the digital image data directly in a predetermined area of the memory 48.

  Digital image data stored in a predetermined area of the memory 48 is read out by the digital signal processing unit 30 under the control of the CPU 40, and a white balance is adjusted by applying a digital gain according to a predetermined physical quantity. Processing and sharpness processing are performed to generate 8-bit digital image data.

  The digital signal processing unit 30 performs YC signal processing on the generated 8-bit digital image data to generate a luminance signal Y and chroma signals Cr and Cb (hereinafter referred to as “YC signal”), and the YC signal. Are stored in an area different from the predetermined area of the memory 48.

  The LCD 38 is configured to display a moving image (through image) obtained by continuous imaging by the CCD 24 and can be used as a finder. When the LCD 38 is used as a finder, the LCD 38 is generated. The YC signals thus output are sequentially output to the LCD 38 via the LCD interface 36. As a result, a through image is displayed on the LCD 38.

Here, when the release button 56A is pressed halfway by the user, after the AE function is activated and the exposure state is set as described above, the AF function is activated and focus control is performed, and then the fully pressed state is continued. In this case, the YC signal stored in the memory 48 at this time is compressed in a predetermined compression format (in this embodiment, JPEG format) by the compression / decompression processing circuit 54 and then passed through the external memory interface 50. To the memory card 52.
<Variable focus>
3 and 4 show the variable focus lens 21 according to the first embodiment of the present invention.

  As shown in FIG. 3, the variable focus lens 21 according to the first embodiment of the present invention includes a plurality of lenses and is configured as a zoom lens capable of changing (magnifying) the focal length.

  The variable focus lens 21 is fixed to the camera 10 by a mount 64, and the focal length can be changed by moving the zoom lens 70 in the optical axis direction (left and right direction in the figure), thereby changing the photographing magnification.

  That is, when a zoom motor (not shown) rotates the cam ring 68, the zoom lens 70 moves in the optical axis direction by the pin 74A fitted to the zoom cam 76 provided on the cam ring 68 as shown in FIG. Since the movement of the zoom lens 70 in the rotation direction is restricted by the shaft 80A, the zoom lens 70 linearly moves in the optical axis direction in accordance with the rotation of the cam ring 68, and changes the focal length of the variable focus lens 21.

  At this time, in the conventional lens, since the initial position of the focus lens 72 is fixed regardless of the position of the zoom lens 70 as shown in FIG. 8, the focusing operation is always started from the fixed initial position at the time of focusing. For this reason, the amount of extension of the focus lens 72 increases depending on the zoom position, and it takes time to focus.

  In the present embodiment, the focus frame 60 including the focus motor 62 is moved in the optical axis direction by the pin 74B fitted to the focus cam 78 provided in the cam ring 68, and the initial position of the focus lens 72 is moved, thereby focusing. The amount of feeding required for the focusing operation can be reduced, and the time required for the focusing operation can be shortened.

  As shown in FIG. 4, a zoom motor (not shown) rotates the cam ring 68, so that a pin 74A fitted to a zoom cam 76 provided on the cam ring 68 moves the zoom lens 70 in the optical axis direction. At the same time, the pin 74B fitted to the focus cam 78 provided on the cam ring 68 also moves the focus frame 60 in the optical axis direction. Since the movement of the focus frame 60 in the rotation direction is restricted by the shaft 80B, the focus frame 60 moves linearly in the optical axis direction in accordance with the rotation of the cam ring 68, and moves the focus frame 60 in the optical axis direction.

  As a result, the focus motor 62 fixed to the focus frame 60 also moves in the optical axis direction at the same time. Therefore, the home position of the focus lens 72 also moves in the optical axis direction, and the amount of extension of the focus lens 72 necessary for focusing is reduced. can do. For this reason, the time for moving the focus lens 72 is reduced, and the time required for focusing can be reduced. Further, since the lead screw 66 for moving the focus lens 72 can be shortened, the total length of the variable focus lens 21 can be shortened.

  FIG. 5 shows the relationship between the zoom position of the variable focus lens according to the first embodiment of the present invention and the number of drive pulses of the focus motor.

  As shown in FIG. 5, when the variable focus lens 21 is zoomed, the number of drive pulses of the focus motor 62 necessary for focusing varies during zooming from W (wide angle) to T (telephoto). When the initial position is fixed, the maximum is about 800 pulses (focus position 0.8 m).

  On the other hand, in the present embodiment, the number of drive pulses of the focus motor 62 necessary for focusing is set as described above by extending the focus frame position to the subject side in accordance with the zoom position as indicated by XX in the figure. The position of about 800 pulses can be reduced to about 270 pulses, and the number of drive pulses of the focus motor 62 can be reduced, so that the focusing operation can be performed at high speed.

  In the present embodiment, macro imaging areas are provided at the tele end and the wide end, respectively, and the initial position of the focus lens 72 is shifted to the payout side by the focus cam 78. As a result, the number of drive pulses of the focus motor 62 up to the position of the focus lens 72 (◯ in the figure) at the time of focusing in macro shooting can be reduced, so that the focusing operation at the time of macro shooting can be speeded up. Yes.

  FIG. 6 shows the shapes of the zoom cam and the focus cam of the variable focus lens according to the first embodiment of the present invention.

  When the entire lens is retracted and stored in the camera 10 when not in use, as shown in FIG. 6, the zoom lens 70 is linearly extended when the lens is moved to the wide angle operation, and zooming is stopped in the wide macro area provided at the wide end. In this state, the focus lens 72 is extended to support close-up photography, and the initial position of the focus lens 72 is shifted to the extension side by the focus cam 78, so that the focusing operation during macro photography can be speeded up. At the time of zooming from the normal wide angle to the telephoto, the zoom lens 70 is moved linearly again.

  At this time, the focus frame 60 also moves in the optical axis direction according to the curve of the focus cam 78 provided on the cam ring 68 in accordance with the zoom operation. As a result, the focusing lens 72 starts focusing from the extended state as described above, so that the time required for the focusing operation is shortened and the lead screw 66 for moving the focusing lens 72 can be shortened, so that the variable focus can be achieved. The total length of the lens 21 can also be shortened.

  When zooming further to the telephoto side than the telephoto end, the telemacro region provided at the telephoto end is entered, the zoom lens 70 stops moving again, and the focus lens 72 moves to the payout side according to the curve of the focus cam 78. At this time as well, as with the wide macro side, the initial position of the focus lens 72 is shifted to the feed-out side by the focus cam 78, and the focusing operation during macro photography where the feed-out amount increases can be speeded up.

  FIG. 7 shows an operation at the time of focusing of the zoom lens and the focus lens of the variable focus lens according to the first embodiment of the present invention.

  As shown in FIG. 7, when the photographer operates the zoom button 56F in step 100 to perform a zooming operation, in step 102, the cam ring 68 rotates and the zoom lens 70 moves in the optical axis direction. Change (step 112). This is the same as the conventional example, but in the present invention, the focus frame 60 is also moved in the optical axis direction in Step 104, and the focus motor 62 fixed thereto is also moved simultaneously, so that the home position of the focus lens 72 is reached. Are also moved (step 106).

  As a result, the home position, which is the starting point of the focusing operation, can be moved in a direction that reduces the amount of movement of the focus lens 72. Therefore, the focus motor 62 is driven in the following step 108, and the lead screw 66 is driven in step 110. , And the focus lens 72 is moved in the optical axis direction to shorten the time required for focusing.

  In the above embodiment, the AF lens is taken as an example, but the present invention can also be applied to a manual focus lens in which a photographer manually focuses.

  Further, the present invention can be applied not only to a digital camera using the CCD 24 but also to a film camera using a silver salt film.

It is a top view which shows the camera containing the variable focus lens which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the camera which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the variable focus lens which concerns on Embodiment 1 of this invention. It is a perspective view which shows the structure of the variable focus lens which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the zoom position of the variable focus lens which concerns on Embodiment 1 of this invention, and a focus moving amount | distance. It is a figure which shows the cam shape of the variable focus lens which concerns on Embodiment 1 of this invention. It is a flowchart which shows the focusing operation | movement of the camera which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the conventional zoom lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Camera 21 Variable focus lens 60 Focus frame 62 Focus motor 66 Lead screw 68 Cam ring 70 Zoom lens 72 Focus lens 74 Pin 76 Zoom cam 78 Focus cam

Claims (3)

A variable focus lens capable of changing a focal length by moving a part of the optical element in the optical axis direction by rotating a cam ring,
It has a focus lens that moves in the direction of the optical axis and performs focusing.
A variable focus lens, wherein a home position of the focus lens moves in conjunction with rotation of the cam ring.
Extending the focus lens as a macro area on one or both of the tele end of the cam ring or the wide side of the wide end than the tele end,
2. The variable focus lens according to claim 1, wherein a home position of the focus lens moves in conjunction with rotation of the cam ring in the macro region.
The variable focus lens according to claim 1, wherein a home position of the focus lens moves toward the subject side in conjunction with rotation of the cam ring.

Images