JP4837351B2 - Imaging device - Google Patents

Description

The present invention relates to a photographing apparatus for photographing the image of the Utsushitai light.

  In recent years, zoom functions and autofocus functions have been applied not only to normal-sized cameras but also to small-sized imaging devices mounted on mobile phones and the like, and it is common to have multiple lenses in the imaging device It is becoming. Also, the miniaturization of the lens itself and the use of new types of imaging devices such as digital video cameras have led to the multiplexing of lenses provided in the imaging device.

  By the way, when shooting a subject under strong light such as outdoors in fine weather, when sunlight enters the lens from outside the field of view, the lens mirror that holds the lens surface and lens It may be reflected by the trunk or the like and reach the imaging surface, causing a ghost in the captured image. In particular, in an imaging apparatus provided with a plurality of lenses as described above, light is reflected in multiples by a plurality of lenses, so harmful light that causes ghosts also enters the imaging surface from multiple directions in a complex manner. There is a problem that it is difficult to remove ghosts in image processing or the like.

  As a method for preventing ghosts, there is known a method in which a flare prevention plate for blocking harmful light incident from outside the photographing field angle is provided in the photographing apparatus. However, in wide-angle shooting that takes a wide angle of view, all the light incident on the entire lens is used to generate a shot image, whereas in telephoto that takes a narrow angle of view, The light incident on the peripheral portion except the central portion is not necessary for generating the captured image, and the light incident on the peripheral portion becomes harmful light. For this reason, if a flare prevention plate is provided at a position that matches the effective diameter of the lens during wide-angle shooting, light that was not harmful during wide-angle shooting becomes harmful light during telephoto shooting. Will occur. Conversely, if a flare prevention plate is installed at a position that matches the effective lens diameter during wide-angle shooting, the shooting angle of view will be blocked by the flare prevention plate during telephoto shooting, and part of the shot image taken at wide angle will be dark. There is a problem that it ends up.

In this regard, Patent Document 1 discloses a flare-preventing plate and a lens barrel that are composed of a plurality of wings surrounding an optical axis in a photographing apparatus equipped with a zoom function in which a lens barrel protrudes in accordance with a photographing field angle. Are connected by a cam mechanism, and the overlapping degree of a plurality of wings is changed according to the protruding position of the lens barrel, and the size of the opening formed by these wings is adjusted. No. 2 describes a technique in which a hood is provided in front of the lens, and the hood is moved in the front-rear direction by a motor or the like in accordance with the protruding position of the lens to adjust a region where light enters. According to the techniques described in Patent Document 1 and Patent Document 2, since the area that blocks light is adjusted according to the shooting angle of view, the ghost can be reduced with high accuracy regardless of the shooting angle of view.
Japanese Patent Laid-Open No. 4-133011 Japanese Patent Laid-Open No. 9-15476

  However, in recent years, the downsizing of photographing apparatuses has been rapidly progressing, and in such a small photographing apparatus, the size, storage space, power consumption, and the like of components are greatly limited. It is difficult to provide a flare prevention plate using a motor or a cam mechanism.

  In view of the above circumstances, the present invention provides a small optical barrel capable of accurately preventing a ghost regardless of a shooting angle of view, a light controller that transmits light, and a photographing device that captures an image of subject light. The purpose is to provide.

An optical lens barrel of the present invention that achieves the above object includes an optical container that accommodates an optical system that forms an image of subject light, a container provided with an optical path through which the subject light passes, and
A stray light preventing plate is provided that prevents light from being reflected by the container and mixed with the subject light, and that expands and contracts by applying and releasing voltage to change the size of the optical path.

  According to the optical barrel of the present invention, the stray light prevention plate expands and contracts due to the application of voltage and the size of the optical path is adjusted, so that the effective diameter of the optical system is changed by changing the focal length or the like. However, the problem that harmful light is mixed with subject light can be reliably prevented. In addition, since a motor, a cam mechanism, and the like are not required, a photographing apparatus on which an optical barrel is mounted can be downsized, and harmful light can be prevented for power saving.

  In the optical barrel of the present invention, it is preferable that the stray light prevention plate is composed of a polymer actuator.

  The polymer actuator has a property of being deformed in accordance with an applied voltage and further has a large amount of deformation, so that it can be preferably applied as a stray light preventing plate according to the present invention.

  In the optical barrel of the present invention, it is preferable that the stray light preventing plate is provided with an optical opening through which an optical path passes and expands and contracts by applying and releasing a voltage to change the size of the opening.

  By providing an opening in the stray light prevention plate and adjusting the size of the opening by applying and releasing voltage, harmful light in all directions can be prevented with a simple mechanism.

Further, the light controller of the present invention that achieves the above object includes an optical system that accommodates an optical system that forms an image of subject light, and is provided with an optical path through which the subject light passes,
A stray light prevention plate that prevents the light from being reflected by the container and mixed with the subject light, and expands and contracts by applying and releasing a voltage to change the size of the optical path;
And a controller that controls the size of the optical path by controlling the application and release of voltage to the stray light prevention plate.

  According to the light controller of the present invention, the size of the optical path through which the subject light passes can be controlled to save power, and the problem that the light is reflected by the container and mixed with the subject light can be surely avoided.

  The light controller referred to in the present invention is only shown here in its basic form, but the light controller referred to in the present invention includes not only the above basic form but also each of the optical barrels described above. Various forms corresponding to the form are included.

In addition, an imaging apparatus of the present invention that achieves the above object includes an optical container that accommodates an optical system that forms an image of subject light, and a container provided with an optical path through which the subject light passes.
A stray light prevention plate that prevents the light from being reflected by the container and mixed with the subject light, and expands and contracts by applying and releasing a voltage to change the size of the optical path;
A control unit that controls the size of the optical path by controlling the application of voltage to the stray light prevention plate, and
And an imaging unit that captures an image of subject light formed by an optical system.

  According to the photographic device of the present invention, even in a small photographic device having no power or internal space, it is possible to reliably avoid a problem that a ghost is generated in a photographed image and acquire a high-quality photographed image.

In the photographing apparatus of the present invention, “the optical system has a variable focal length,
It has a focal length adjustment unit that adjusts the focal length of the optical system,
It is preferable that the control unit controls the size of the optical path to a size corresponding to the focal length adjusted by the focal length adjusting unit.

Since the shooting angle of view is wide when the focal length is short, a bright shot image can be obtained by increasing the size of the optical path through which the subject light passes. When the focal length is long, the shooting angle of view is narrow and the optical path By reducing the size of
By increasing the size of the optical path of the subject light when the focal length is short (ie, the shooting angle of view is wide), and by decreasing the size of the optical path when the focal length is long (ie, the shooting angle of view is narrow) Regardless of the focal length, it is possible to avoid the occurrence of ghosts with high accuracy.

Further, in the photographing apparatus of the present invention, “comprising a luminance detection unit for detecting the luminance of the subject,
A configuration in which the control unit controls the size of the optical path to a size corresponding to the luminance detected by the luminance detection unit is suitable.

  According to the imaging device of the preferred embodiment of the present invention, the stray light prevention plate serves as a flare prevention plate that prevents harmful light from being mixed into the subject light and a diaphragm that restricts the luminous flux of the subject light according to the luminance. The number of points can be reduced, and the photographing apparatus can be downsized.

Further, in the photographing apparatus of the present invention, "the stray light prevention plate is provided on the front surface of the container,
A container drive unit for projecting and retracting the container with respect to the photographing apparatus;
When the container is retracted in the photographing apparatus by the container driving unit, the control unit preferably causes the stray light prevention plate to close the optical path.

  When the container is retracted in the photographing apparatus and photographing is not performed, the optical system can be protected without providing a new lens cover or the like by closing the optical path with the stray light prevention plate.

  Note that only the basic form of the photographing apparatus according to the present invention is shown here, but the photographing apparatus according to the present invention includes not only the above basic form but also each form of the optical barrel described above. Various corresponding forms are included.

  According to the present invention, it is possible to provide a small optical barrel capable of accurately preventing a ghost regardless of a shooting angle of view, a light controller that transmits light, and a photographing device that captures an image of subject light. Can do.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 are external perspective views of a digital camera to which an embodiment of the present invention is applied.

  FIG. 1 shows the retracted state of the lens barrel 10 in which the photographing lens of the digital camera 1 is built, and FIG. 2 shows the extended state of the lens barrel 10. In the present embodiment, when the lens barrel 10 is retracted, as shown in FIG. 1, a flare prevention plate 70, which will be described later, covers the front surface of the photographing lens, and when photographing is performed, it is shown in FIG. As described above, the lens barrel 10 is extended, the flare prevention plate 70 is opened, and light is incident on the photographing lens.

  An auxiliary light emission window 12 and a viewfinder objective window 13 are arranged at the upper front of the digital camera 1 shown in FIGS. A shutter button 14 is provided on the top of the digital camera 1.

  On the rear surface (not shown) of the digital camera 1, various switches such as a zoom operation switch and a cross key, and an LCD (liquid crystal display) for displaying images and menu screens are provided. Press and hold the zoom operation switch for a predetermined time to enter the zoom operation mode to adjust the shooting angle of view, and the photographic lens moves to the telephoto side (tele side) while pressing the “up” key of the cross key. Then, while the “down” key of the cross key is kept pressed, the photographing lens moves to the wide angle side (wide side).

  FIG. 3 is a cross-sectional view of the digital camera 1 in a retracted lens barrel 10 taken along the optical axis. FIG. 4 is a cross-sectional view of the digital camera 1 in which the photographing lens is in a wide state. Is a cross-sectional view taken along the optical axis, and FIG. 5 is a cross-sectional view taken along the optical axis of the lens barrel 10 of the digital camera 1 in which the photographing lens is in the telephoto state.

  In the inner space of the lens barrel 10, there are three groups of a front lens group (first lens group) 21, a rear lens group (second lens group) 22, and a focus lens (third lens group) 23 in order from the front. A photographic lens is arranged in which the optical axes are aligned. The photographing lens changes the field angle of view when the rear lens group 22 moves along the optical axis between the wide end shown in FIG. 4 and the telephoto end shown in FIG. 5, and the focus lens 23 follows the optical axis. By moving the camera, the focus is adjusted. The front group lens 21, the rear group lens 22, and the focus lens 23 correspond to an example of an optical system according to the present invention, and the lens barrel 10 corresponds to an example of an optical lens barrel according to the present invention.

  In front of the front lens group 21, a flare prevention plate 70 that blocks harmful light is disposed. Between the front lens group 21 and the rear lens group 22, a diaphragm unit 30 that adjusts the amount of subject light is disposed. A CCD 40 for reading subject light is disposed behind the photographing lens. The CCD 40 corresponds to an example of the imaging unit referred to in the present invention.

  The flare prevention plate 70 is provided with an optical opening through which an optical path passes, and is configured by a polymer actuator (described later) that expands and contracts when a voltage is applied / released. In the retracted state shown in FIG. 3, the flare prevention plate 70 extends to close the opening, thereby covering the front surface of the photographic lens and protecting the photographic lens. As shown in FIGS. 4 and 5, when the lens barrel 10 is extended, the flare prevention plate 70 is contracted to increase the size of the opening, and light is incident on the photographing lens through the opening. The flare prevention plate 70 will be described in detail later. The flare prevention plate 70 corresponds to an example of the stray light prevention plate according to the present invention.

  As shown in FIGS. 4 and 5, the diaphragm unit 30 includes an aperture plate 32 having a hole surrounding the optical axis of the photographic lens, and an aperture for closing the aperture of the aperture plate 32 to adjust the aperture amount. Feather 31 is provided. The diaphragm unit 30 is also provided with a guide lot 24 protruding rearward from the back surface thereof and a stopper 24a for closing the rear end of the guide lot 24. The guide lot 24 holds the rear group lens 22. The rear group lens holding frame 25 is slidably penetrated in the optical axis direction. Further, a coil spring 26 is mounted between the diaphragm unit 30 and the rear group lens holding frame 25, and the diaphragm unit 30 includes a rear group composed of the rear group lens 22 and the rear group lens holding frame 25. The lens unit 27 is held so as to be movable along the optical axis in a manner in which the lens unit 27 is spring-biased forward. When the lens barrel 10 is retracted, the diaphragm blades 31 shown in FIGS. 4 and 5 are opened, and the diaphragm unit 30 moves toward the rear group lens unit 27 while compressing the coil spring 26. The rear lens group unit 27 enters. Thereby, thickness reduction of the digital camera 1 is achieved.

  The lens barrel 10 is provided with a fixed cylinder 50 fixed to the camera body and a drive cylinder 52 that is rotatable with respect to the fixed cylinder 50. The drive cylinder 52 has a protrusion 50 a formed in the circumferential direction on the outer peripheral surface of the fixed cylinder 50 and is engaged with a groove provided on the inner peripheral surface of the drive cylinder 52. Therefore, movement in the optical axis direction is restricted. A gear 51 is provided on the outer peripheral surface of the driving cylinder 52, and a driving force from a motor (not shown) is transmitted to the gear 51 to rotate the driving cylinder 52.

  The drive cylinder 52 is further provided with a key groove 52a extending in the optical axis direction. A pin-like cam follower 54 fixed to the rotationally movable cylinder 53 is provided in the fixed cylinder 50 in the key groove 52a. It penetrates through the formed spiral cam groove. Accordingly, when the drive cylinder 52 rotates, the rotational movement cylinder 53 moves in the optical axis direction along the cam groove while rotating.

  A rectilinear movement frame 55 is provided inside the rotational movement cylinder 53. The rectilinearly moving frame 55 is engaged with the rotationally movable cylinder 53 so as to be freely rotatable relative thereto, and the rotation of the rectilinearly moving frame 55 is restricted by engaging with the key groove 50 b of the fixed cylinder 50. Therefore, when the rotationally movable cylinder 53 moves in the optical axis direction while rotating with the rotation of the drive cylinder 52, the rectilinear movement frame 55 moves linearly in the optical axis direction with the movement of the rotationally movable cylinder 53.

  A pin-shaped cam follower 63 is fixed to the rear group lens holding frame 25 that holds the rear group lens 22 described above. The cam follower 63 is engaged with the cam groove of the rotationally movable cylinder 53 and also is engaged with the key groove 55a extending in the optical axis direction of the rectilinearly moving frame 55, so that the drive cylinder 52 is rotated. When the rotationally moving barrel 53 rotates and moves in the optical axis direction, the rear lens group unit 27 moves straight in the optical axis direction along the shape of the cam groove of the rotationally movable barrel 53.

  Further, as described above, since the diaphragm unit 30 is attached to the lens unit 27 in a state of being biased forward by the coil spring 26, the diaphragm unit 30 moves in the optical axis direction together with the rear group lens unit 27. To do.

  Further, the lens barrel 10 is provided with a rectilinearly moving cylinder 56 that holds the front group lens 21. The straight movement cylinder 56 has a cam follower 57 fixed thereto engaged in a cam groove of the rotation movement cylinder 53 and also in a key groove 55a of the linear movement frame 55 extending in the optical axis direction. Yes. Accordingly, when the rotationally movable cylinder 53 moves in the optical axis direction as the drive cylinder 52 rotates, the rectilinearly movable cylinder 56 follows the shape of the cam groove of the rotationally movable cylinder 53 in which the cam follower 57 is engaged. And move straight in the direction of the optical axis.

  In this way, the lens barrel 10 is extended, and the lens barrel 10 is retracted by rotating the drive cylinder 52 in the reverse direction. The fixed barrel 50, the drive barrel 52, the rotationally movable barrel 53, and the rectilinearly movable barrel 56 are an example of a container according to the present invention, and a gear 51 provided to project / collapse the lens barrel 10, and A combination of a motor and the like provided on the gear 51 corresponds to an example of a container drive unit according to the present invention.

  Further, even after the feeding of the lens barrel 10 is completed, the rotationally movable cylinder 53 can be further rotated while maintaining the position of the front group lens 21, and at this time, the rear group lens unit 27 is rotated. It moves along the cam groove 53 in the direction of the optical axis, thereby adjusting the shooting angle of view (ie, focal length). FIG. 4 shows a state in which the feeding of the lens barrel 10 is completed. At this time, the photographing lens 20 is in the wide state. FIG. 5 shows a state in which the rear moving lens unit 27 is moved until the rotation moving cylinder 53 is further rotated after the feeding is completed and the photographing lens 20 is in the telephoto state. A combination of the rotationally movable cylinder 53 and the rear lens group holding frame 25 corresponds to an example of a focal length adjusting unit according to the present invention.

  Further, the focus lens 23 of the photographic lens has a lead screw 61 rotated by a motor (not shown), and a focus lens holding frame 62 holding the focus lens 23 is screwed into the lead screw 61. As the lead screw 61 rotates, the focus lens 23 moves in the optical axis direction, and focus adjustment is performed.

  Next, the internal configuration of the digital camera 1 will be described.

  FIG. 6 is a schematic internal configuration diagram of the digital camera 1 shown in FIG.

  In the digital camera 1 of the present embodiment, all processes are controlled by the main CPU 110. The main CPU 110 includes various switches provided in the digital camera 1 (the various switches include the shutter button 14 shown in FIG. 1, the zoom operation switch, the cross key, and the like. Operation signals are supplied from the switch group 101). The main CPU 110 has an EEPROM 110a, and various programs necessary for executing various processes by the digital camera 1 are written in the EEPROM 110a. When a power switch (not shown) included in the switch group 101 is turned on, power is supplied from the power source 102 to various elements of the digital camera 1, and the digital camera 1 is programmed by the main CPU 110 according to the program procedure written in the EEPROM 110a. Overall operation is controlled centrally.

  First, the flow of an image signal will be described with reference to FIG.

  When the photographer instructs a shooting angle of view using a cross key (not shown) provided on the back of the digital camera 1, the designated shooting angle of view is transmitted from the switch group 101 to the main CPU 110. In the main CPU 110, a focal length corresponding to the instructed shooting angle of view is calculated, and the calculated focal length is transmitted to the optical control CPU 120. Note that data is not transmitted / received between the main CPU 110 and the optical control CPU 120 via the bus 140, but is transmitted / received at high speed by inter-CPU communication. The optical control CPU 120 controls a motor or the like (not shown) to extend the lens barrel 10 as shown in FIGS. 4 and 5 and further move the rear lens group 22 to a position corresponding to the transmitted focal length. . The EEPROM 101a stores a focal length and a voltage value for adjusting the opening of the flare prevention plate 70 to a size corresponding to the effective lens diameter at the focal length in association with each other. To the optical control CPU 120 is also notified of the voltage value associated with the calculated focal length. The optical control CPU 120 instructs the voltage application unit 70a to apply a voltage having a voltage value transmitted from the main CPU 110. In the present embodiment, the polymer actuator constituting the flare prevention plate 70 has a property of expanding when a voltage is applied and contracting when the application of the voltage is stopped, and the lens barrel 10 is retracted. Sometimes, a predetermined voltage is applied from the voltage application unit 70a to the flare prevention plate 70, and the flare prevention plate 70 extends to close the opening. Further, when the lens barrel 10 is extended, the voltage applied to the flare prevention plate 70 is controlled by the optical control CPU 120, the flare prevention plate 70 is shrunk and an opening is opened, and the subject light passes through the opening to the photographing lens. Is incident. A combination of the main CPU 110 and the optical control CPU 120 corresponds to an example of a control unit according to the present invention.

  Further, the optical control CPU 120 controls a motor or the like (not shown) to move the focus lens 23 shown in FIGS. 3, 4, and 5 in a direction along the optical axis.

  The subject light is imaged on the CCD 40 through the flare prevention plate 70, the photographing lens, and the aperture unit 30, and the CCD 40 generates an image signal representing the subject image. The generated image signal is roughly read out by the A / D unit 131, the analog signal is converted into a digital signal, and low resolution through image data is generated. The generated through image data is subjected to image processing such as white balance correction and γ correction in a white balance / γ processing unit 133.

  Here, a timing signal is supplied from the clock generator 132 to the CCD 40, and an image signal is generated at predetermined intervals in synchronization with the timing signal. The clock generator 132 outputs a timing signal based on an instruction from the main CPU 110 transmitted via the optical CPU 120. The timing signal is output from the CCD 40, the A / D unit 131 in the subsequent stage, the white balance The γ processing unit 133 is also supplied. Therefore, the CCD 140, the A / D unit 131, and the white balance / γ processing unit 133 perform the processing of the image signals in order in synchronization with the timing signal generated from the clock generator 132.

  The image data subjected to the image processing in the white balance / γ processing unit 133 is temporarily stored in the buffer memory 134. The low-resolution through image data stored in the buffer memory 134 is supplied to the YC / RGB conversion unit 138 via the bus 140 first from the through image data stored at the old time. Since the through image data is an RGB signal, the YC / RGB conversion unit 138 does not perform processing, but directly transmits the image to the image display LCD 160 via the driver 139, and the through image represented by the through image data is displayed on the image display LCD 160. Is displayed. Here, in the CCD 140, since the subject light is read at every predetermined timing and an image signal is generated, the subject light in the direction in which the photographing lens is directed is always displayed on the image display LCD 160 as a subject image. to continue.

  The through image data stored in the buffer memory 134 is also supplied to the main CPU 110. Based on the through image data, the main CPU 110 detects the contrast of the subject image represented by the image signal repeatedly obtained by the CCD 40 while the focus lens 23 is moved along the optical axis, and the luminance of the subject. The detected contrast and brightness are transmitted to the optical control CPU 120. The main CPU 110 corresponds to an example of a luminance detection unit referred to in the present invention.

  The optical control CPU 120 moves the focus lens 23 to a lens position where the contrast peak transmitted from the main CPU 110 is obtained (AF processing), and adjusts the aperture value of the aperture unit 30 according to the brightness transmitted from the main CPU 110. (AE processing).

  Here, when the photographer presses the shutter button 14 shown in FIG. 1 while confirming the through image displayed on the image display LCD 160, the main CPU 110 is notified that the shutter button 14 has been pressed, and further optical control is performed. This is transmitted to the CPU 120. When the subject is dark, a light emission instruction is transmitted from the optical control CPU 120 to the LED light emission control unit 150, and a flash is emitted from the LED 151 in synchronization with the pressing of the shutter button 14. Further, in accordance with an instruction from the optical control CPU 120, the image signal generated by the CCD 40 is finely read out by the A / D unit 131, and high-resolution captured image data is generated. The generated captured image data is subjected to image processing by the white balance / γ processing unit 133 and stored in the buffer memory 134.

  The captured image data stored in the buffer memory 134 is supplied to the YC processing unit 137 and converted from RGB signals to YC signals. The captured image data converted into the YC signal is subjected to compression processing in the compression / decompression unit 135, and the compressed captured image data is stored in the memory card 170 via the I / F 136.

  The captured image data stored in the memory card 170 is subjected to decompression processing in the compression / decompression unit 135, converted into RGB signals in the YC / RGB conversion unit 138, and then displayed on the image display LCD 160 via the driver 139. Reportedly. On the image display LCD 160, a captured image represented by the captured image data is displayed.

  The digital camera 1 is configured as described above.

  Here, in the digital camera 1 of the present embodiment, the size of the opening provided in the flare prevention plate 70 is adjusted by applying and releasing a voltage according to the focal length to the flare prevention plate 70. First, the configuration of the flare prevention plate 70 and a method for adjusting the size of the opening by the flare prevention plate 70 will be described.

  FIG. 7 is a view for explaining the operating principle of the flare prevention plate 70.

  As shown in FIG. 7, the flare prevention plate 70 is configured by sandwiching a polymer material 73 between two electrodes 71 and 72. In the present embodiment, the electrodes 71 and 72 are configured by mixing an opaque metal material or the like with a stretchable material, and the flare prevention plate 70 has a light shielding property by these electrodes 71 and 72. The polymer material 73 applicable to the present invention will be described later.

  The two electrodes 71 and 72 and the polymer material 73 have a circular plate shape, and an opening 70 ′ is formed in a central portion of the circle. The flare prevention plate 70 is disposed in front of the photographing lens with the central axis of the opening 70 ′ aligned with the optical axis of the photographing lens. The opening 70 'corresponds to an example of the opening referred to in the present invention.

  When no voltage is applied to the flare prevention plate 70 from the voltage application unit 70a also shown in FIG. 6, the two electrodes 71 and 72 are not attracted as shown in part (A) of FIG.

  For example, when a voltage having a polarity in which the upper electrode 71 serves as an anode and the lower electrode 72 serves as a cathode is applied to the flare prevention plate 70 from the voltage application unit 70a, as shown in Part (B) of FIG. A positive charge 71 is released to the electrode 71, and a negative charge 72 is released to the lower electrode 72. As a result, the positive charge 71 and the negative charge 72 released to the two electrodes 71 and 72 are attracted to each other by the electrostatic force, and the polymer material 73 is pressed between the two electrodes 71 and 72. As a result, the flare prevention plate 70 is thinned and contracted so that the opening 70 ′ is crushed. Here, since the magnitude of the electrostatic force formed by the two electrodes 71 and 72 varies depending on the magnitude of the voltage applied from the voltage application section 70a, the magnitude of the opening 70 ′ can be adjusted by adjusting the applied voltage. Can be controlled.

  When the application of voltage from the voltage application unit 70a is stopped, the electrostatic force between the two electrodes 71 and 72 disappears, and the flare prevention plate 70 contracts as shown in part (A) of FIG. The opening 70 'is enlarged.

  The size of the opening 70 ′ provided in the flare prevention plate 70 is adjusted as described above.

  Next, the focal length and the size of the opening 70 ′ of the flare prevention plate 70 will be described.

  FIG. 8 is a diagram showing the relationship between the effective lens diameter at the shortest focal length and the opening 70 ′ of the flare prevention plate 70.

  The photographing lens functions as a telephoto lens when the focal length (the distance between the rear lens group 22 and the CCD 40) is long, and functions as a wide-angle lens when the focal length is short.

  As shown in Part (A) of FIG. 8, when the rear group lens 22 is moved away from the front group lens 21 and moved to the position of the shortest focal length, the photographing field angle is wide and the effective diameter of the front group lens 21 is increased. W1 is the same size as the diameter of the front lens group 21. That is, all the light incident from the entire area of the front lens group 21 is read by the CCD 40 and used to generate photographed image data.

  When the shortest focal length is selected, the voltage application from the voltage application unit 70a shown in FIG. 7 to the electrodes 71 and 72 is stopped. As a result, as shown in part (B) of FIG. 8, the flare prevention plate 70 is contracted to increase the thickness, and the aperture diameter of the aperture 70 ′ is the effective diameter W1 of the front lens group 21 (= the diameter of the front lens group 21). Is adjusted to the same size. As a result, the light incident from the entire area of the front lens group 21 is not blocked by the flare prevention plate 70, and a problem that a part of the photographed image becomes dark is avoided.

  FIG. 9 is a diagram showing the relationship between the effective lens diameter at the longest focal length and the opening 70 ′ of the flare prevention plate 70.

  As shown in Part (A) of FIG. 9, when the rear group lens 22 is moved closer to the front group lens 21 and moved to the position of the longest focal length, the shooting angle of view is narrowed, and the effective diameter of the front group lens 21 is reduced. W2 is smaller than the diameter of the front lens group 21. Therefore, the light incident on the peripheral region R outside the effective diameter W2 of the front lens group 21 was not harmful light at the shortest focal length shown in part (A) of FIG. ) Becomes harmful light at the longest focal length shown in FIG. 2, and when this harmful light reaches the CCD 40, a ghost is generated in the captured image.

  When the longest focal length is selected, a voltage having a large voltage value is applied to the electrodes 71 and 72 from the voltage applying unit 70a shown in FIG. As a result, as shown in Part (B) of FIG. 9, the flare prevention plate 70 extends and becomes thin, and the opening diameter of the opening 70 ′ is the effective diameter W2 of the front group lens 21 (the effective diameter W2 of the front group lens 21 < It is adjusted to the same size as the diameter of the front lens group 21). As a result, the light incident from the peripheral region R is blocked by the flare prevention plate 70, and the light incident from the region within the effective diameter W2 reaches the CCD 40, so that a ghost is generated in the photographed image. While avoiding with high precision, the malfunction that a part of picked-up image becomes dark is also avoided.

  As described above, the effective diameter of the lens decreases as the focal length increases, and the effective diameter of the lens increases as the focal length decreases. In the digital camera 1 of the present embodiment, the focal length and the opening diameter of the opening 70 'provided in the flare prevention plate 70 are the same as the effective diameter of the front lens group 21 at the focal length in the EEPROM 110a shown in FIG. Are stored in association with voltage values for adjustment.

  When the photographer changes the shooting angle of view using a cross key (not shown) provided in the digital camera 1, the main CPU 110 calculates a focal length corresponding to the changed shooting angle of view and calculates it from the EEPROM 110a. The voltage value associated with the focal length is acquired, and the acquired voltage value is transmitted to the optical control CPU 120.

  The optical control CPU 120 transmits an instruction to apply the voltage transmitted from the main CPU 110 to the voltage application unit 70 a, and the voltage application unit 70 a applies the instructed voltage to the flare prevention plate 70.

  The flare prevention plate 70 expands and contracts according to the applied voltage, and as a result, the opening diameter of the opening 70 ′ is adjusted to the same size as the effective diameter of the front lens group 21 at the calculated focal length.

  The light incident from the outside of the effective lens diameter of the front lens group 21 is blocked by the flare prevention plate 70, and only the light incident from the effective lens diameter of the front lens group 21 reaches the CCD 40 and is taken image data. Used to generate Therefore, according to the digital camera 1 of the present embodiment, it is possible to avoid a ghost with high accuracy regardless of the focal length (shooting angle of view), and to acquire a high-quality shot image. Furthermore, since no motor or the like is used for the flare prevention plate 70, power consumption can be suppressed and the digital camera 1 can be miniaturized.

  Further, in the digital camera 1 of the present embodiment, as shown in FIG. 1, when the lens barrel 10 is retracted, the opening 70 'of the flare prevention plate 70 is closed, and the flare prevention plate 70 is placed on the front surface of the photographing lens. Covering. For this reason, it is not necessary to provide components such as a lens cover and a motor for opening and closing the lens cover, and the number of components can be reduced.

  Above, description of 1st Embodiment of this invention is complete | finished and 2nd Embodiment of this invention is described. The second embodiment of the present invention is different from the first embodiment in that a flare prevention plate is not provided, but other than that, since it has substantially the same configuration as the first embodiment, the same elements are used. Are denoted by the same reference numerals, description thereof will be omitted, and only differences will be described.

  FIG. 10 is a cross-sectional view of the lens barrel 10 ′ of the digital camera of the second embodiment cut along the optical axis.

  The lens barrel 10 ′ in the present embodiment shown in FIG. 10 has substantially the same configuration as the lens barrel 10 in the first embodiment shown in FIG. Is not provided with a flare prevention plate 70, and is provided with a diaphragm 30 'having the same configuration as the flare prevention plate 70 shown in FIG.

  FIG. 11 is a schematic internal configuration diagram of the digital camera according to the second embodiment.

  The digital camera of this embodiment includes a voltage application unit 30a that applies a voltage to the diaphragm 30 instead of the voltage application unit 70a for the flare prevention plate 70 shown in FIG. In the present embodiment, first, the maximum aperture diameter of the diaphragm 30 is determined according to the focal length corresponding to the shooting angle of view specified by the photographer, and further, the diaphragm according to the luminance of the subject detected by the main CPU 110. A throttling amount of 30 is determined.

  FIG. 12 is a diagram showing the relationship between the focal length and the maximum aperture diameter of the diaphragm 30. As shown in FIG.

  In part (A) of FIG. 12, the rear lens group 22 is set to the shortest focal length (that is, wide angle). As described with reference to FIG. 8, at the shortest focal length, the effective diameter W1 of the front lens group 21 is the same as the diameter of the front lens group 21, and all the light incident from the entire area of the front lens group 21 is CCD 40. Is used to generate captured image data. Therefore, the aperture diameter at which the aperture stop 30 ′ is maximally opened at this shortest focal length is determined as a length W <b> 3 ′ corresponding to the diameter of the front lens group 21 (= the effective diameter W <b> 1 of the front lens group 21). .

  In part (B) of FIG. 12, the rear group lens 22 is set to the longest focal length (that is, telephoto). As described with reference to FIG. 9, at the longest focal length, the effective diameter W2 of the front lens group 21 is smaller than the diameter W1 of the front lens group 21, and the light incident from the peripheral region R outside the effective diameter W2 is Harmful light. The aperture diameter when the diaphragm 30 'is opened to the maximum at the longest focal length is determined as a length W2' corresponding to the effective diameter W2 of the front lens group 21 at the longest focal length. In the present embodiment, since the flare prevention plate 70 shown in FIG. 9 is not provided, light is also incident from the peripheral region R. However, harmful light that has entered from the peripheral region R is blocked by the diaphragm 30 ′. , Ghosting is avoided.

  In the digital camera of the present embodiment, the focal length and the maximum aperture diameter of the diaphragm 30 ′ corresponding to the effective diameter of the front lens group 21 at the focal length are stored in the EEPROM 110a shown in FIG. In addition, the diaphragm amount of the diaphragm 30 'and the voltage value for adjusting the aperture of the diaphragm 30' to the diaphragm amount are stored in association with each other.

  Similar to the first embodiment, when the photographer designates a shooting angle of view using a cross key (not shown) provided in the digital camera 1, the photographing designated by the main CPU 110 from the switch group 101 shown in FIG. The angle of view is conveyed. The main CPU 110 calculates the focal length corresponding to the designated shooting angle of view, and acquires the maximum aperture diameter of the diaphragm 30 ′ associated with the calculated focal length from the EEPROM 110a.

  When the through image generated by roughly reading the subject light is transmitted to the main CPU 110, the main CPU 110 detects the luminance of the subject based on the through image. Based on the calculated luminance, the main CPU 110 calculates the temporary aperture amount of the aperture 30 ′, and the total when the aperture of the aperture 30 ′ is further reduced by the temporary aperture amount calculated from the acquired maximum aperture diameter. The aperture amount is calculated. Further, the main CPU 110 acquires a voltage value associated with the calculated total aperture amount from the EEPROM 110a, and transmits the acquired voltage value to the optical control CPU 120.

  The optical control CPU 120 transmits an instruction to apply the voltage transmitted from the main CPU 110 to the voltage application unit 30a, and the voltage application unit 30a applies the instructed voltage to the diaphragm 30 '. As a result, the aperture of the diaphragm 30 'is adjusted to a size corresponding to the luminance of the subject.

  In this way, the number of parts can be reduced by removing harmful light by the diaphragm 30 '. Further, the ghost can be removed even when the aperture 120 is opened, and the ghost can be removed even when a bright photographed image is acquired.

  Above, description of 2nd Embodiment of this invention is complete | finished.

  Subsequently, various forms that can be adopted in each component constituting the present invention will be additionally described.

  For the stray light prevention plate according to the present invention, a polymer actuator having electrodes is preferably employed. Regarding polymer actuators, “Forefront of Soft Actuator Development: Aiming at Realization of Artificial Muscles” Editor-in-Chief Yoshihito Nagata NTS 2004, “Electroactive Polymers (EAP) Actuators as Artificial Muscles-Reality, Potential Challenges "Editor: Joseph Bar-Cohen SPIE PRESS Vol. 2001, “Electroactive Polymer (EAP) Actuators as Artificial Mussles: Reality, Potential, and Challenges, Second Edition”, Editor B (s): Yoseh 200.

  Examples of the polymer actuator used in the present invention include a polymer gel, an ion conductive polymer, an electron conductive polymer, an electrostrictive polymer (dielectric elastomer, electrostatic elastomer), a piezoelectric polymer, and a liquid crystal elastomer. However, polymer gels, electrostrictive polymers, liquid crystal elastomers and the like are preferable, and electrostrictive polymers are particularly preferable.

  As the polymer actuator used in the present invention, one having a light shielding property is preferable. Regarding the provision of light shielding properties, a method of applying a light shielding material to the polymer surface, a method of adding a light shielding material to the polymer, a method of using the electrode as a light shielding material, and the like can be used, but the electrode is used as a light shielding material. The method is preferred.

  As an example of a polymer gel, an actuator using a phenomenon that a polymer electrolyte gel having a charge on a polymer network takes in a solvent such as water by an electric field change and expands / contracts by discharge is known. For example, JP-A-5-44706 discloses a polymer gel that instantaneously contracts in the direction of the electric field by application of an electric field and expands in the orthogonal direction, and exhibits deformation behavior in a different direction by the electric field. Japanese Patent Laid-Open No. 5-87042 discloses a micropump using a polymer gel actuator, and Japanese Utility Model Laid-Open No. 5-57551 discloses a linear actuator using a polymer gel actuator.

As an example of an electrostrictive polymer (dielectric elastomer), an electrostrictive polymer actuator in which electrodes are provided on both sides of a polymer (elastomer) that exhibits rubber-like viscoelastic behavior is known. For example, in Japanese Patent Publication No. 2003-506858, an electrode having the ability to deform together with a strain having a conformable portion at a contact portion is applied, and a high voltage is applied between the electrodes, thereby static electricity between the electrodes. An electrostrictive polymer actuator utilizing the characteristic that a polymer film contracts in the direction of the electric field and expands in the direction perpendicular to the electric field due to the electric attractive force is disclosed, and its use as a diaphragm or a linear actuator is considered. Furthermore, Japanese translations of PCT publication No. 2003-526213 also discloses a heel-grounding generator that is incorporated into a shoe heel and used to convert mechanical energy generated during human bipedal walking into electrical energy. It is disclosed.
<Liquid crystal elastomer>
In Nature, 410, 447 (2001), an attempt to convert electrical energy into mechanical energy using an elastomer of ferroelectric liquid crystal and utilizing the change in orientation of mesogen due to the electric field was reported. It is attracting attention as a law. In this example, a displacement of 4% is realized at an applied voltage of 1.5 MVm ⁻¹ . Japanese Patent Laid-Open No. 2003-20596 also discloses a liquid crystal actuator that is stretched in the longitudinal direction and uses a liquid crystal elastomer. Further, in Macromolecules magazine, 34, 5868 (2001), it is reported that a shape (volume) change based on a thermal phase change of liquid crystal is used as an actuator.

  Here, the example of the flare prevention plate provided with the opening has been described above. However, the stray light prevention plate according to the present invention is such that a plate that expands and contracts in the length direction due to the application of voltage is suspended from the upper part of the main body housing. It may be.

  In the above description, the example in which the stop is disposed between the front group lens and the rear group lens has been described. However, the stray light prevention plate according to the present invention is disposed, for example, between the rear group lens and the focus lens. It may be used as an aperture.

  In the above description, an example of a flare prevention plate having holes is described. However, the stray light prevention plate according to the present invention is physically provided with a hole as long as an optical opening is provided. It does not have to be a thing.

  In the above description, an example in which the optical lens barrel according to the present invention is applied to a digital camera has been described. However, the optical lens barrel of the present invention is, for example, a mobile phone or a silver salt camera that forms an image of subject light on a film. You may apply to.

1 is an external perspective view of a digital camera to which an embodiment of the present invention is applied. 1 is an external perspective view of a digital camera to which an embodiment of the present invention is applied. 1 is a cross-sectional view of a digital camera 1 in which a lens barrel 10 in a retracted state is cut along an optical axis. FIG. 2 is a cross-sectional view of the digital camera 1 taken along the optical axis of a lens barrel 10 with a photographing lens in a wide state. FIG. 2 is a cross-sectional view of the digital camera 1 taken along the optical axis of a lens barrel 10 with a photographing lens in a tele state. It is a schematic internal block diagram of the digital camera 1 shown in FIG. It is a figure for demonstrating the principle of operation of the flare prevention board. FIG. 6 is a diagram illustrating a relationship between an effective lens diameter at the shortest focal length and an opening 70 ′ of the flare prevention plate 70. FIG. 6 is a diagram showing the relationship between the effective lens diameter at the longest focal length and the opening 70 ′ of the flare prevention plate 70. It is sectional drawing which cut | disconnected lens barrel 10 'of the digital camera of 2nd Embodiment along the optical axis. It is a schematic internal block diagram of the digital camera of 2nd Embodiment. 6 is a diagram illustrating a relationship between a focal length and a maximum aperture diameter of a diaphragm 30. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 10 Lens barrel 12 Auxiliary light emission window 13 Finder objective window 14 Shutter button 21 Front group lens 22 Rear group lens 23 Focus lens 24 Guide lot 24a Stopper 25 Rear group lens holding frame 26 Coil spring 27 Rear group lens unit 30 Aperture unit 31 Aperture blade 32 Aperture plate 40 CCD
50 fixed cylinder 50a protrusion 50b key groove 51 gear 52 drive cylinder 52a key groove 53 rotational movement cylinder 54 cam follower 55 rectilinear movement frame 55a key groove 56 rectilinear movement cylinder 61 lead screw 62 focus lens holding frame 63 cam follower 70 flare prevention plate 70 ' Opening 71, 72 Electrode 73 Polymer material 101 Switch group 110 Main CPU
110a EEPROM
120 Optical control CPU
131 A / D unit 132 Clock generator 133 White balance / γ processing unit 134 Buffer memory 135 Compression / decompression unit 136 I / F
137 YC processing unit 138 YC / RGB conversion unit 139 driver 140 bus 150 LED light emission control unit 151 LED
160 Image display LCD
170 Memory card

Claims (4)

A container that contains an optical system that forms an image of the subject light and that is provided with an optical path through which the subject light passes;
A stray light prevention plate that prevents light from being reflected by the container and mixed with the subject light, and expands and contracts by applying and releasing a voltage to change the size of the optical path;
A control unit that controls the size of the optical path by controlling the application of voltage to the stray light prevention plate;
An imaging unit that captures an image of the subject light formed by the optical system;
The stray light prevention plate is provided on the front surface of the container,
A container drive unit for projecting and retracting the container with respect to the photographing apparatus;
The controller is configured to cause the stray light prevention plate to close the optical path when the container is retracted in the photographing apparatus by the container driving unit. The optical system has a variable focal length,
A focal length adjustment unit for adjusting a focal length of the optical system;
The imaging apparatus according to claim 1, wherein the control unit controls the size of the optical path to a size corresponding to the focal length adjusted by the focal length adjustment unit.   The photographing apparatus according to claim 1, wherein the stray light prevention plate is formed of a polymer actuator.   2. The photographing apparatus according to claim 1, wherein the stray light preventing plate is provided with an optical opening through which the optical path passes, and expands and contracts by applying and releasing voltage to change the size of the opening. .

Images