JP5921253B2 - Viewfinder device and imaging device using the same - Google Patents

Description

  The present invention relates to a finder device for an image pickup apparatus and an image pickup apparatus using the same, and particularly relates to prevention of unnecessary reflected light generated in an eyepiece.

  Conventionally, many imaging devices including a finder device have been proposed.

  By photographing using the viewfinder device, the photographer can surely observe the subject image even under a bright light source such as the sun or a lighting fixture. However, light emitted from such a bright light source may enter the finder optical path from the finder eyepiece, be reflected by an internal lens, and become ghost light and enter the photographer's field of view. In such a case, it becomes difficult for the photographer to observe the subject image, which hinders the photographing operation.

  Various inventions have been proposed that suppress the generation of ghost light that hinders the observation of the subject image.

  For example, Patent Document 1 discloses an invention in which a peripheral light flux of an eyepiece constituting a finder device is shielded by printing a light shielding sheet material, a light shielding paint, and a light shielding member.

  Further, Patent Document 2 discloses an invention in which unnecessary light is shielded by providing a protrusion at the edge of the viewfinder opening on the eyepiece side of the viewfinder device.

JP 2002-82370 A JP-A-8-220597

  In the prior art disclosed in Patent Document 1, it is assumed that a thin light-shielding sheet material is assembled, a light-shielding paint, and a light-shielding member are printed, which increases the workload during manufacturing. It also leads to an increase in costs such as parts costs and painting costs.

  In the prior art disclosed in Patent Document 2, since the projection is provided at the edge of the finder opening, the camera is increased in size. In addition, the presence of the protruding portion limits the specifications of accessories that can be attached to a finder device such as an eye cup or an angle finder.

  Therefore, the object of the present invention is to suppress the generation of harmful ghost light without adding a thin light-shielding sheet material, light-shielding paint, or adding a printing process for the light-shielding member or increasing the size of the viewfinder eyepiece, An object of the present invention is to provide an imaging device having a finder device that ensures good visibility.

Therefore, the present invention provides a first lens positioned closest to the photographer in the optical axis direction, a field mask positioned closer to the subject side than the first lens in the optical axis direction, and the field in the optical axis direction. A finder device comprising: a second lens positioned on the subject side of the mask; and a holding member that holds the first lens, the field mask, and the second lens,
In the optical axis direction, the first lens is attached to the holding member from the photographer side,
The opening diameter of the first opening on the photographer side of the field mask is larger than the opening diameter of the second opening on the subject side of the field mask,
In the cross section including the optical axis, the outer edge of the first lens is a first tapered surface in which the distance from the optical axis in the direction perpendicular to the optical axis is reduced toward the subject starting from a ridge line constituting the outer edge. And the second taper surface where the distance in the direction perpendicular to the optical axis from the optical axis is reduced toward the photographer side starting from the ridge line ,
In the cross section including the optical axis, the ridge line includes an opening end of the first opening on the photographer side of the field mask and a second opening on the subject side of the field mask in the cross section including the optical axis. It is characterized in that it is positioned closer to the subject side in the optical axis direction than the intersection of the straight line connecting the open ends with the straight line extending to the photographer side and the second tapered surface.

  According to the present invention, it is possible to provide an imaging apparatus capable of ensuring good visibility and preventing unnecessary light without adding a light shielding process.

It is detail drawing of an eyepiece. It is a 1st block diagram of a camera system. It is a 2nd block diagram of a camera system. It is a block diagram of the camera function. It is a perspective view of a finder apparatus. It is a perspective view of a finder apparatus. It is a perspective view of a finder apparatus. It is a detailed view of a lens. It is a longitudinal cross-sectional view of the conventional finder apparatus.

  Hereinafter, as an example of an imaging apparatus according to an embodiment of the present invention, a configuration of a digital single lens reflex camera system will be described with reference to FIGS.

  2 and 3 are schematic cross-sectional views illustrating the configuration of the camera system according to the present embodiment, which includes a camera main body (imaging device) 101 and a lens device 102 that is detachably attached to the camera main body 101. . FIG. 2 shows a state of the camera system when an object is observed with an optical viewfinder (OVF). The state shown in FIG. 2 is hereinafter referred to as “optical viewfinder mode (OVF mode)”.

  FIG. 3 shows the camera system when the subject can be observed using an electronic viewfinder (EVF) function for sequentially displaying the subject image on the display unit 107 (display means) attached to the back of the camera body 101. Indicates the state.

  The state shown in FIG. 3 is hereinafter referred to as “electronic finder mode (EVF mode)”.

  In the lens device 102, an imaging optical system 103 (imaging lens) including a focus lens (not shown) and an aperture 104 for adjusting the exposure amount are provided. The lens device 102 is electrically and mechanically connected to the camera body 101 via a known mount mechanism. By attaching the lens apparatus 102 having different focal lengths to the camera body 101, it is possible to obtain shooting screens having various angles of view. The lens device 102 adjusts the focus of the photographing optical system 103 by moving a focus lens, which is a part of the photographing optical system 103, in the direction of the optical axis L1 via a driving mechanism (not shown).

  The camera body 101 is a single-plate digital color camera using an image sensor 106 such as a CCD sensor or a CMOS sensor. The image signal representing a moving image or a still image by driving the image sensor 106 continuously or once. Get. The imaging element is a type of area sensor that converts exposed light into an electrical signal for each pixel, accumulates charges according to the amount of received light, and reads the accumulated charges. The image sensor 106 is housed in a package 110.

  Further, in the optical path from the photographic optical system 103 to the image sensor 106, the cutoff frequency of the photographic optical system 103 is set so that a spatial frequency component higher than necessary for the subject image (optical image) is not transmitted to the image sensor 106. A limiting optical low pass filter 156 is provided.

  As the image sensor 106, for example, an image sensor having a total of about 10 million square pixels can be used. In addition, a so-called Bayer array is formed in which R (red), G (green), and B (blue) color filters are alternately arranged in each pixel to form a set of four pixels. In the Bayer array, the overall image performance is improved by arranging more G pixels that are easily felt when an observer views the image than the R and B pixels.

  In general, in image processing using this type of image sensor, a luminance signal is generated mainly from G, and a color signal is generated from R, G, and B. Needless to say, the number of pixels and the type of color filter are not limited to those described above, and known ones can be used as appropriate.

  Further, when the image sensor 106 is constituted by a CMOS process compatible sensor (hereinafter abbreviated as “CMOS sensor”) which is one of the amplification type solid-state image sensors, it can have the following characteristics. That is, since the MOS transistors of the area sensor section and peripheral circuits such as the image sensor driving circuit, A / D conversion circuit, and image processing circuit can be formed in the same process, the number of masks and process processes can be greatly reduced compared to the CCD. There are advantages. Further, it has a feature that random access to an arbitrary pixel is possible, reading out for a display is easy, and real-time display can be performed on the display unit 107 at a high display rate.

  The signal read from the image sensor 106 is displayed on the display unit 107 as image data after being subjected to predetermined processing as will be described later. The display unit 107 is attached to the back of the camera body 101 so that the user can directly observe the display on the display unit 107.

  The image sensor 106 uses the above-described features, and performs a low-definition image output operation of the display (reading out from a part of the light-receiving area of the image sensor 106) and a high-definition image output operation of the display ( Both reading operations from the entire light receiving area can be performed. In addition, focus adjustment by a contrast detection method using the output of the image sensor 106 can be performed.

Reference numeral 111 denotes a movable half mirror that reflects a part of the light beam of the subject optical image incident through the photographing optical system 103 and transmits the remaining light, thereby dividing one optical path into two optical paths. Reference numeral 105 denotes a focusing screen arranged on a predetermined image formation surface of a subject image formed by the photographing optical system 103, and 112 denotes a hollow pentamirror having a mirror deposited inside. Reference numeral 109 denotes a finder lens for observing a subject image formed on the focusing screen 105.
Generally, it is composed of a plurality of lenses. The focusing screen 105, the hollow pentamirror 112, and the finder lens 109 constitute a finder optical system. Reference numeral 180 denotes an information display unit in the optical viewfinder for displaying specific information on the focusing screen 105.

  A movable sub-mirror 122 is provided behind the half mirror 111 (on the image plane side), and a focus detection unit (focus detection means) 121 is reflected by reflecting a beam close to the optical axis L1 among the beams transmitted through the half mirror 111. Leading to. Further, the sub mirror 122 can be moved back and forth with respect to the photographing optical path in conjunction with the half mirror 111 by a driving mechanism (not shown). That is, the half mirror 111 and the sub mirror 122 which are movable mirrors are in any of two positions, the position shown in FIG. 2 (first position) in the OVF mode and the position shown in FIG. 3 (second position) in the EVF mode. Can be taken selectively.

  The focus detection unit 121 receives a subject optical image from the sub-mirror 122 and performs focus detection by a phase difference detection method.

  Reference numeral 113 denotes a focal plane shutter that adjusts the amount of light incident on the image plane, and has a front curtain and a rear curtain composed of a plurality of light shielding blades. The camera body 101 has a main switch (not shown) for starting the camera body.

  A release button (not shown) is pressed in two stages, and a shooting preparation operation (photometry operation, focus adjustment operation, etc.) is started by a half-press operation (ON of the switch SW1). Further, a shooting operation (running of the focal plane shutter 113, exposure of the image sensor 106, reading of the charge signal, and processing of the charge signal and image data obtained by processing the charge signal by full-pressing operation (ON of the switch SW2) is performed. Recording) starts.

  There is a finder mode switching switch (not shown), and each time the switch is pressed, switching between OVF mode and EVF mode can be performed as a subject image observation mode. It is also possible to switch between the OVF mode and the EVF mode from the menu screen.

  FIG. 4 is a block diagram showing a schematic functional configuration of the digital color camera shown in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof is omitted.

  First, a description will be given from the part related to the imaging and recording of the subject image.

  The camera system of the present embodiment has an imaging system, an image processing system, a recording / reproducing system, and a control system. The imaging system has a photographing optical system 103 and an imaging element 106, and the image processing system has an A / D converter 130, an RGB image processing circuit 131, and a YC processing circuit 132. The recording / reproducing system includes a recording processing circuit 133 and a reproducing processing circuit 134, and the control system includes a camera system control circuit 135, an operation detection circuit 136, an image sensor driving circuit 137, an AF control circuit 140, and a lens system control circuit. 141.

  Reference numeral 138 denotes a connection terminal that is connected to an external computer, a storage medium, or the like and is standardized to transmit and receive data. The electric circuit described above is driven by receiving power from a small battery (not shown).

  The imaging system is an optical processing system that forms an image of light from a subject on the imaging surface of the imaging element 106 via the imaging optical system 103. By controlling the driving of the diaphragm 104 provided in the lens device 102 and controlling the driving of the focal plane shutter 113 as necessary, the image sensor 106 can receive an appropriate amount of subject light.

  A signal read from the image sensor 106 is supplied to an image processing system including an A / D converter 130. Image data is generated by image processing in this image processing system. The A / D converter 130 converts, for example, an output signal of the image sensor 106 into, for example, a 10-bit digital signal according to the amplitude of the signal read from each pixel of the image sensor 106 and outputs the signal. The subsequent image processing is executed by digital processing. The image processing system is a signal processing circuit that obtains an image signal in a desired format from R, G, and B digital signals. The R, G, and B color signals are converted into a luminance signal Y and a color difference signal (R−Y), ( B-Y) and the like are converted into a YC signal.

  The RGB image processing circuit 131 is a signal processing circuit that processes the output signal of the A / D converter 130, and includes a white balance circuit, a gamma correction circuit, and an interpolation calculation circuit that performs high resolution by interpolation calculation.

  The YC processing circuit 132 is a signal processing circuit that generates a luminance signal Y and color difference signals RY and BY. The YC processing circuit 132 generates a high-frequency luminance signal generation circuit that generates a high-frequency luminance signal YH, a low-frequency luminance signal generation circuit that generates a low-frequency luminance signal YL, and generates color difference signals RY and BY. A color difference signal generating circuit. The luminance signal Y is formed by combining the high frequency luminance signal YH and the low frequency luminance signal YL. The luminance signal Y and the color difference signals RY and BY (chroma signals) output from the YC processing circuit 132 are hereinafter collectively referred to as “YC signal”.

  The recording / reproducing system is a processing system that outputs an image signal to a memory (not shown), an external computer, or an external storage medium, and outputs an image signal to the display unit 107. The recording processing circuit 133 performs writing processing and reading processing of image signals to and from a memory, an external computer, and an external storage medium, and the reproduction processing circuit 134 reproduces image signals read from the memory, the external computer, and the external recording medium, and displays them. Output to unit 107. Note that the image signal read from the memory may be not only a captured image but also an image for a display screen prepared in advance for the user to make various camera settings.

  The recording processing circuit 133 includes a compression / decompression circuit that compresses the YC signal representing the still image data and moving image data output from the YC processing circuit 132 in a predetermined compression format and decompresses the compressed data. Have. The compression / decompression circuit has a frame memory or the like for signal processing. The YC signal from the YC processing circuit 132 is stored in this frame memory for each frame, and the YC signal for each frame is read for each of a plurality of blocks. To compress and encode.

  The reproduction processing circuit 134 is a circuit that converts the YC signal into a matrix suitable for the display unit 107 such as an RGB signal. The signal converted by the reproduction processing circuit 134 is output to the display unit 107 and displayed (reproduced) as a visible image.

  On the other hand, the operation detection circuit 136 in the control system detects operations of a main switch (not shown), a release button, a finder mode changeover switch, and other various switches. Then, this detection result is output to the camera system control circuit 135. The camera system control circuit 135 receives the detection signal from the operation detection circuit 136 and controls the imaging system, the image processing system, and the recording / reproducing system in accordance with the detection result. For example, when the switch SW2 is turned on by operating the release button, the driving of the half mirror 111 and the sub mirror 122 and the driving of the focal plane shutter 113 are controlled.

  Furthermore, in addition to the operation of the AF control circuit 140 that processes the detection signal in the focus detection area obtained by the focus detection unit 121, the image sensor 106 is driven, the RGB image processing circuit 131 is operated, and the recording processing circuit 133 is compressed. Control etc.

  The camera system control circuit 135 generates a timing signal for performing an imaging operation and outputs the timing signal to the imaging element driving circuit 137. The image sensor drive circuit 137 receives the control signal from the camera system control circuit 135 and generates a drive signal for driving the image sensor 106. The information display circuit 139 receives a control signal from the camera system control circuit 135 and controls driving of the information display unit 180 in the optical viewfinder.

  Next, the configuration within the lens device 102 will be described. The lens system control circuit 141 performs control for moving the focus lens included in the photographing optical system 103 to the in-focus position via the lens driving circuit 142. In addition, the lens system control circuit 141 controls the driving of the diaphragm 104 via the diaphragm driving circuit 143 according to the subject brightness during the photographing operation. The lens system control circuit 141 can communicate with the camera system control circuit 135 in the camera body 101 via the communication contact 102a on the lens device 102 side and the communication contact 101a on the camera body 101 side. The lens system control circuit 141 notifies the camera system control circuit 135 of the type and focal length of the lens device 102.

  When the camera body 101 is in the OVF mode (the state shown in FIG. 2), the diaphragm 104 of the lens device 102 is controlled to the open state. The half mirror 111 and the sub mirror 122 are in the first position on the photographing optical path, and the front curtain and the rear curtain of the focal plane shutter 113 are charged by a shutter charge mechanism including an electromagnetic motor and a gear train (not shown). . By charging, the leading curtain is closed and the trailing curtain is opened.

  Therefore, the image sensor 106 is not exposed. The light beam of the subject optical image incident from the photographing optical system 103 is reflected by the half mirror 111 and guided to the finder optical system, and the light beam transmitted through the half mirror 111 is reflected by the sub mirror 122 and guided to the focus detection unit 121. . Therefore, the subject optical image can be observed through the finder lens 109, and the focus detection unit 121 can perform focus detection (shooting standby in the OVF mode). Normally, the OVF mode is set when the main switch is turned off and immediately after the main switch is turned on.

  In the EVF mode shown in FIG. 3, the half mirror 111 and the sub mirror 122 are in the second position retracted from the photographing optical path, and the light beam from the photographing optical system 103 is directly guided to the image sensor 106. In this state, the imaging device 106 continuously performs imaging of a subject image, reads out the obtained charge from the imaging device 106 for display, and sequentially displays it on the display unit 107, thereby displaying in real time. To do. Thus, the photographer can determine the composition while confirming the subject image displayed on the display unit 107.

  In this EVF mode, focus detection by the contrast detection method using the output of the image sensor 106 can be performed without using the focus detection unit 121 (shooting standby in the EVF mode).

  5, 6 and 7 show schematic views of the configuration of the viewfinder device provided in the single-lens reflex camera according to the embodiment of the present invention. FIG. 5 is a perspective view of the finder device, FIG. 6 is a longitudinal sectional view of an eyepiece portion of the finder device, and FIG. 7 is a transverse sectional view of an eyepiece portion of the finder device.

  In these drawings, reference numeral 200 denotes a first lens holding member that holds a lens constituting the funder optical system, 201 denotes a focus washer that adjusts the position of the focusing screen 105, and 202 denotes the focusing screen to the first lens holding member 200. It is a spring member hold | maintained to.

  Reference numeral 203 denotes a field frame that limits the field size of the finder beam when the subject image that has passed through the photographing lens 102 enters the finder optical system via the reflection of the half mirror 111. Reference numeral 204 denotes a mirror that performs image reversal together with the hollow pentamirror 112 and folds the subject image transmitted through the field frame 203 in the direction of the eyeball of the photographer to form an erect image. Reference numeral 205 denotes a spring member for fixing and holding the hollow pentamirror 112 to the first lens holding member 200, and is fixed by pressing the projection of the hollow pentamirror 102 with the spring member 205 with a screw.

  Reference numeral 109-1 denotes a first lens of the finder optical system, which is assembled and fixed to the first lens holding member 200 from above. Reference numeral 109-2 denotes a second lens of the finder optical system, which is adhered and held on the second lens holding member 208. The second lens holding member 208 is integrally formed with a hole for fitting with the shaft 206 and a shaft for guiding the spring 207 that biases the second lens toward the photographer. By fitting the shaft 206 into the fitting hole provided in the first lens holding member 200 and the fitting hole of the second lens holding member 208, the second lens holding member 208 is moved in the direction of the finder optical axis La. It is configured to slide.

  The diopter (finder diopter) is adjusted to an arbitrary position by moving the second lens 109-2 held by the second lens holding member 208 in the direction of the finder optical axis La via the gear and the cam 209. it can. Reference numeral 109-3 denotes a third lens of the finder optical system, which is bonded and fixed to the first lens holding member 200. A field mask 210 cuts unnecessary light and suppresses occurrence of a finder ghost. Reference numeral 109-4 denotes a fourth lens, which is bonded and fixed to the first lens holding member 200. Reference numeral 211 denotes an eyepiece frame, which is fixed to the first lens holding member 200 with screws. Reference numeral 211 a denotes an eyepiece opening provided in the eyepiece frame 211.

  The eye cup 212 can be attached by being inserted into a rail groove (not shown) provided in the eyepiece frame 211, and is a member that improves the user's feeling of use.

  The moving mechanism of the second lens 109-2 in the finder optical axis La direction is not limited to the above method, and any method may be used.

  Further, the finder optical system may include a lens in addition to 109-1, 109-2, 109-3, 109-4, or may have a configuration in which the number of lenses is less than four.

  FIG. 1 shows the detailed shape of the eyepiece frame 211 of the fourth lens 109-4 and the first lens holding member 200.

  The third lens 109-3 is incorporated into the first lens holding member 200 from the photographer side (right side in FIG. 1), and is fixed by adhesion. Similarly, the field mask 210 is incorporated and fixed to the first lens holding member 200 from the photographer side.

  The field mask 210 has an opening 210a on the subject side (left side in FIG. 1) and an opening 210b on the photographer side. The opening end of the opening 210b on the photographer side is the opening end of the opening 210a on the subject side. The distance from the viewfinder optical axis La is further increased. In other words, the opening of the field mask 210 is tapered so as to open toward the photographer side, and the opening diameter of the first opening 210b on the photographer side of the field mask 210 is the field mask. The opening diameter of the second opening 210a on the subject side 210 is larger.

  The field mask 210 is created by molding a resin material with a mold. The tapered surface is a shape in which the inclined shape of the mold is transferred.

  The fourth lens 109-4 is also incorporated into the first lens holding member 200 from the photographer side, and is fixed by adhesion. The fourth lens 109-4 is attached to the first lens holding member 200 from the photographer side.

  The upper and lower side surfaces of the fourth lens 109-4 are a first tapered surface 109-4b that opens toward the photographer side and a second taper that narrows toward the photographer side. A tapered surface 109-4a is provided. An intersection line between the first tapered surface 109-4a and the second tapered surface 109-4b is an edge 109-4c forming a ridge line. In general, a part having a shape like the fourth lens 109-4 is often formed by a mold that is divided into a subject side and a photographer side, and the edge 109-4c is a parting line at that time. The fourth lens 109-4 in the present embodiment is molded by a mold as described above using a resin that satisfies predetermined optical characteristics.

  The point where the line connecting the openings 210a and 210b of the field mask 210 intersects the side surface of the fourth lens 109-4 is 109-4f. As is apparent from FIG. 1, the edge 109-4c is located closer to the subject than the point 109-4f, that is, the line connecting the openings 210a and 210b of the field mask 210. With such a configuration, the edge 109-4c of the fourth lens 109-4 is inevitably secured with respect to the opening of the field mask 210, so that the incident light R from the subject side is generated. Even when the light is reflected by the tapered surfaces 109-4a and 109-4b of the fourth lens 109-4, the incident light R is cut by the field mask 210, and the surface 109-3R2 on the photographer side of the third lens 109-3. It is possible to prevent ghost light from being reflected.

  In other words, in the cross section including the optical axis La, the outer edge of the first lens 109-4 is directed to the subject side constituting the outer edge, and the first tapered surface 109 has a smaller distance in the direction perpendicular to the optical axis from the optical axis La. -4a and the first tapered surface 109-4b that intersects with the first tapered surface 109-4a that forms the outer edge, and the second tapered surface 109-4b that has a smaller distance in the direction perpendicular to the optical axis from the optical axis La toward the photographer. Configured.

  In the cross section including the optical axis La, the ridge line 109-4c corresponds to the opening end of the first opening 210b on the photographer side of the field mask 210 and the second opening on the subject side of the field mask 210 in the cross section including the optical axis. It is located closer to the subject side in the optical axis direction than the intersection of the straight line connecting the open end of the portion 210a and the second tapered surface 109-4a.

  Further, as indicated by incident light R ′ in FIG. 1, a light beam incident at an incident angle θ2 larger than the incident angle θ1 of the incident light R with respect to the optical axis La is cut by the eyepiece opening 211a. Is done. Therefore, the eyepiece opening 211a also contributes to the prevention of ghosts caused by light rays being reflected by the tapered surfaces 109-4a and 109-4b of the fourth lens 109-4.

  As is clear from FIG. 1, the eyepiece opening 211 a of the eyepiece frame 211 is closer to the optical axis La than the second opening 210 a of the field mask 210. It is possible to reduce unnecessary incident light from the eyepiece frame 211 by shortening the distance in the optical axis orthogonal direction between the optical axis La and the opening end 211b on the optical axis side of the eyepiece opening 211a of the eyepiece frame 211.

  That is, the eyepiece frame 211 is provided closer to the photographer than the fourth lens 109-4, and the distance from the opening end 211b of the opening 211a of the eyepiece frame 211 to the optical axis La is the opening end of the second opening 210a. Shorter than the distance to the optical axis La. Note that the eyepiece frame 211 is molded of resin and has a material color or surface shape that hardly reflects light rays.

  The side surface in the left-right direction of the fourth lens 109-4 has a sufficient distance from the optical axis La as shown in FIG. 7, and does not become a ghost generation source.

  In the present embodiment, the subject-side surface 109-4R1 of the fourth lens 109-4 is concave toward the subject side, and the distance from the optical axis La to the side surface of the fourth lens 109-4. This is an advantageous configuration for ensuring the above.

  One reason is that the incident light R incident on the lens surface 109-4R1 from the photographer side receives negative power and diverges away from the optical axis La. This is because R is cut by the field mask 210 and can be prevented from becoming ghost light.

  This will be described below with reference to FIG. 8A shows a case where the object side surface 109-4R1 of the fourth lens 109-4 has a convex shape, and FIG. 8B shows an object side surface 109-4R2 of the fourth lens 109-4. This represents the shape when becomes a concave shape.

  When the object-side surface 109-4R1 is convex, the position of the edge 109-4c, which is a parting line at the time of component molding, is positioned between the side surface 109-4d of the fourth lens 109-4 and the object-side surface 109-4R1. The position is set at a predetermined clearance from the intersecting point 109-4e. Therefore, as shown in SECTION A-A, the size of the second tapered surface 109-4b relative to the first tapered surface 109-4a is relatively large in the lens central cross section, and the optical axis La and the first and It becomes difficult to secure the distance between the second tapered surfaces 109-4a and b.

  The distance refers to the optical axis La and the edge 109-4c forming the ridge line when the intersection of the first tapered surface 109-4a and the second tapered surface 109-4b in the direction orthogonal to the optical axis La. .

  Therefore, by making the subject-side surface 109-4R1 concave as shown in FIG. 8B, the size of 109-4b can be significantly reduced relative to 109-4a, and the optical axis It is possible to secure the distance between La and the first and second tapered surfaces 109-4a and b, which is advantageous in suppressing the generation of harmful ghost light.

  In the conventional configuration and the present embodiment, the lower portion of the fourth lens 109-4 is provided with a protrusion 109-4g which is a gate at the time of component molding. Except for the protrusion 109-4g, the fourth lens 109-4 is vertically symmetrical with respect to the optical axis. Since the protrusion 109-4g is further away from the tapered surfaces 109-4a and 109-4b with respect to the optical axis La, the incident light reflected by the 109-4g is less likely to become ghost light.

  FIG. 9 is a longitudinal sectional view of a viewfinder device having a conventional configuration. Parts equivalent to the embodiment of the present invention are indicated by the same numbers. Only portions different from the embodiment of the present invention will be described below.

  In the conventional configuration, the third lens 109-3, the fourth lens 109-4, and the field mask 210 are assembled into the eyepiece frame 211 from the subject side and bonded and fixed. At this time, an adhesive is filled in the gap X between the fourth lens 109-4 and the eyepiece frame 211. In order to ensure the adhesive strength when the fourth lens 109-4 receives a static pressure from the photographer side, the gap X has a sufficiently large volume.

  For this reason, the first tapered surface 109-4b of the fourth lens 109-4 becomes closer to the optical axis La. As is clear from FIG. 9, the edge 109-4c of the fourth lens 109-4 and the first and second tapered surfaces 109-4a, b with respect to the line connecting the openings 210a, 210b of the field mask 210. Is located on the photographer side, not on the subject side.

  For this reason, the light beam R incident from the photographer side is reflected by the first tapered surface 109-4b, and then reflected by the photographer side surface 109-3R2 of the third lens, and becomes a ghost as a ghost. It penetrates into the field of view. Therefore, in the finder having the conventional configuration, it is necessary to suppress reflection of incident light by adding antireflection coating or the like to the first and second tapered surfaces 109-4b and 109-4b of the fourth lens 109-4. Become.

  In this conventional example, the first lens 109-1 (not shown) is attached to the first lens holding member 200, the second lens 109-2 is attached to the second lens holding member 208, and the third and fourth lenses. Since the lenses 109-3 and 109-4 are fixed to the eyepiece frame 211, the lens is likely to be displaced between the optical axes of the lenses, and the display quality of the viewfinder may be impaired.

  5, 6, and 7, the first, third, and fourth lenses other than the movable second lens are positioned and fixed to the first lens holding member 200. Therefore, it is relatively easy to align the optical axes between the lenses, and the display quality of the viewfinder can be improved.

  Further, since the fourth lens 109-4 is incorporated from the photographer side with respect to the first lens holding member 200, the first lens 109-4 is loaded even when the photographer applies a load to the fourth lens 109-4. It is supported by the lens holding member 200. Compared to fixing with only an adhesive having a conventional configuration, there is much less variation in strength due to variations in assembly work, so that finder devices with stable strength can be mass-produced.

  In addition, in order to limit the incidence of unnecessary light, no protrusions are provided on the external appearance part, so that there is no restriction on accessories attached to the eyepiece part.

109-1 First lens of viewfinder optical system 109-2 Second lens of viewfinder optical system 109-3 Third lens of viewfinder optical system 109-4 Fourth lens of viewfinder optical system 112 Hollow pentamirror 180 Optical Information display unit in viewfinder 200 First lens holding member 203 Field frame 205 Spring member 206 Axis 207 Spring 210 Eyepiece frame 211 Eye cup

Claims (4)

A first lens positioned closest to the photographer in the optical axis direction, a field mask positioned closer to the subject side than the first lens in the optical axis direction, and positioned closer to the subject side than the field mask in the optical axis direction. A finder device comprising: a second lens that holds: a holding member that holds the first lens, the field mask, and the second lens;
In the optical axis direction, the first lens is attached to the holding member from the photographer side,
The opening diameter of the first opening on the photographer side of the field mask is larger than the opening diameter of the second opening on the subject side of the field mask,
In the cross section including the optical axis, the outer edge of the first lens is a first tapered surface in which the distance from the optical axis in the direction perpendicular to the optical axis is reduced toward the subject starting from a ridge line constituting the outer edge. And the second taper surface where the distance in the direction perpendicular to the optical axis from the optical axis is reduced toward the photographer side starting from the ridge line ,
In the cross section including the optical axis, the ridge line includes an opening end of the first opening on the photographer side of the field mask and a second opening on the subject side of the field mask in the cross section including the optical axis. A viewfinder device, wherein the finder device is located closer to the subject side in the optical axis direction than an intersection of a straight line obtained by extending a straight line connecting open ends to the photographer side and the second tapered surface.   The viewfinder device according to claim 1, wherein a shape of a lens surface on the subject side of the first lens is a concave shape facing the subject side.   The eyepiece frame is closer to the photographer side than the first lens, and the distance to the optical axis of the opening end of the opening of the eyepiece frame is larger than the distance to the optical axis of the opening end of the second opening. The viewfinder device according to claim 1, wherein the viewfinder device is short.   The imaging device which has a finder apparatus as described in any one of Claims 1 thru | or 3.

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