Patent Publication Number: US-2011048912-A1

Title: Composite rotary switch

Description:
BACKGROUND 
     1. Technical Field 
     The technical field relates to a rotary switch and more particularly to a composite rotary switch including a plurality of rotary operation members of which rotational position can be detected. 
     2. Related Art 
     Various types of apparatuses are proposed that detect a position indicated by an operation member when the operation member is operated, including, for example, one using an electric contact, one using a change in electrical resistance, and one using reflection of light. For example, JP 56-111421 A discloses an apparatus that optically detects a position of an operation member. 
     Recently, amazing technological advances have been made in a field of an imaging apparatus such as a digital still camera, and the imaging apparatus which is small in size but implements various functions has been put on the market. In addition, products directed for users, such as professionals skilled in shooting techniques and high level amateurs, are provided with a number of operation members on the top and back surfaces of the apparatus so that the users can enjoy manual operations. 
     To improve the operability of the operation members, it is desirable to arrange the operation members on a top surface of an imaging apparatus. However, on the top surface of the imaging apparatus, a pop-up type electronic flash, a hot shoe for attaching external accessories, various dials, and switches are already arranged. Hence, it is difficult to provide new operation members on the top surface of the imaging apparatus. 
     In particular, it is very difficult to provide additional operation members on the exterior of the imaging apparatus while satisfying a demand for miniaturization of the imaging apparatus. 
     To solve the above-described problem, a rotary switch is provided that can be arranged even in a small area such as a top surface of an imaging apparatus. 
     SUMMARY 
     In one aspect, a composite rotary switch includes a first rotary operation member configured to be rotatable around a rotational center, a second rotary operation member configured to be rotatable around the rotational center, an electrical position detector operable to electrically detect a rotational position of the first rotary operation member, and an optical position detector operable to optically detect a rotational position of the second rotary operation member. 
     According to the composite rotary switch in one aspect, the two rotary operation members are allowed to have the same rotational center and the rotational positions of the two rotary operation members can be detected independently, and thus additional operation members can be arranged even in a small area. Furthermore, optically detecting a rotational position of one rotary operation member allows the problem of contact failure of an electrical position detector to be improved, the number of components to be reduced, and furthermore, an improvement in reliability to also be achieved. Due to the above-described points, miniaturization and reduction in cost of a rotary switch can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a digital still camera according to an embodiment. 
         FIGS. 2A to 2C  are front, top, and side views of the digital still camera according to the embodiment. 
         FIG. 3  is a diagram showing a state in which a pop-up electronic flash is in use. 
         FIG. 4  is an exploded perspective view of a top surface of the digital still camera according to the embodiment. 
         FIG. 5  is a cross-sectional view of the top surface of the digital still camera according to the embodiment. 
         FIG. 6  is a diagram of a drive mode lever as seen from a top surface thereof. 
         FIG. 7  is a diagram showing a relation between a state of detecting reflection of a reflective photo-coupler and a drive mode. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     An embodiment will be described below with reference to the accompanying drawings. 
     1. Configuration of Digital Still Camera 
       FIG. 1  is a perspective view of a digital still camera including a composite rotary switch.  FIGS. 2A to 2C  are three views of the digital still camera according to the embodiment.  FIG. 2A  is a front view,  FIG. 2B  is a top view, and  FIG. 2C  is a right side view of the digital still camera when the camera is seen from the front side. 
     An interchangeable lens (not shown) is attachable to a digital still camera  100  through a mount  101 .  FIGS. 1 and 2A  to  2 C show a state in which the interchangeable lens is detached from the digital still camera  100 . The interchangeable lens can be attached to the digital still camera  100  by inserting a mount of the interchangeable lens into the mount  101  of the digital still camera  100  and rotating the interchangeable lens clockwise. The interchangeable lens can be detached from the digital still camera  100  by rotating the interchangeable lens counterclockwise while pressing an interchangeable lens detach button  102 . An imaging device  103  provided inside the digital still camera  100  can be seen through an opening of the mount  101 . 
     As shown in  FIG. 2C , a terminal cover  104  that covers various terminals is provided on a right side of a body of the digital still camera  100 .  FIGS. 1 and 2A  to  2 C show a state in which the terminal cover  104  is closed. HDMI terminals for displaying an image on a television set, USB terminals for transferring images to a computer, and so on are contained inside the terminal cover  104 . 
     A number of operation members, a hot shoe  105 , and a pop-up electronic flash  106  are arranged on a top surface of the body of the digital still camera  100 . 
     Accessories such as an external electronic flash with a large amount of light emission, one of various finders, and a high performance external microphone can be attached to the hot shoe  105 . To fix accessories having a certain size and weight, the hot shoe  105  requires a certain size and strength. Therefore, the hot shoe  105  is often configured by a metal member. In addition, to obtain optimum light distribution by an external electronic flash, there is a constraint that the hot shoe  105  needs to be provided on the top surface of the digital still camera  100  and directly above the optical axis. Furthermore, to establish an electrical connection between the digital still camera  100  and various accessories, the hot shoe  105  is provided with a plurality of electric contacts. 
     The pop-up electronic flash  106  is an electronic flash apparatus included in the digital still camera  100 . When the pop-up electronic flash  106  is not in use, as shown in  FIGS. 1 and 2A  to  2 C, the pop-up electronic flash  106  is contained in the digital still camera  100 .  FIG. 3  is a diagram showing a state in which the pop-up electronic flash  106  is in use. In  FIG. 3 , those reference numerals unnecessary to describe the pop-up electronic flash  106  are omitted. In the state in which the pop-up electronic flash  106  is in use, a pop-up electronic flash cover  106   a  rises at an angle of substantially 45° in a back direction of the digital still camera  100 . By this, an electronic flash light emitter  106   h  appears. Therefore, it is difficult provide operation members on a top surface of the pop-up electronic flash cover  106   a.    
     As described above, substantially half the top surface of the digital still camera  100  is occupied by the hot shoe  105  and the pop-up electronic flash  106 . As a result, a number of operation members are crammed into substantially the other half of the top surface of the digital still camera  100 . 
     Referring back to  FIG. 2B , the operation members arranged on the top surface of the body of the digital still camera  100  include a power switch  107 , a recording mode dial  108 , a drive mode lever  109 , a shutter button  110 , and a menu button  111 . 
     The power switch  107  is an operation member for turning on or off the power to the digital still camera  100  by performing a slide operation. A slide type operation member is adopted to avoid accidental power-on/off. Hence, the area occupied by the power switch  107  is about double the area of the menu button  111 . 
     The recording mode dial  108  is a rotary operation member for determining a recording mode. The recording mode of the digital still camera  100  includes an auto recording mode (“iA” shown on a top surface of the recording mode dial  108 ), a program recording mode (“P” is shown likewise), an aperture priority recording mode (“A” is shown likewise), a shutter speed priority recording mode (“S” is shown likewise), a manual recording mode (“M” is shown likewise), and so on. By rotating the recording mode dial  108 , the recording mode can be switched. Since the recording mode dial  108  is a rotary operation member, a certain size is required to enhance operability. 
     The drive mode lever  109  is a lever type operation member for determining a drive mode. The drive mode of the digital camera  100  includes a single shooting mode for taking a single image by pressing operation performed on the shutter button  110 , a continuous shooting mode for taking a plurality of images continuously while the shutter button  110  is pressed, an auto bracket mode for taking a plurality of images while exposure is varied when pressing the shutter button  110 , a self-timer mode for taking an image when a predetermined period of time elapses after the shutter button  110  is pressed, and so on. Rotating of the drive mode lever  109  can switch the drive mode. The drive mode lever  109  is arranged below the recording mode dial  108  and has the same rotational center as the recording mode dial  108 . Therefore, the drive mode lever  109  does not occupy the area of the top surface of the digital still camera  100  almost at all. 
     The shutter button  110  is a button-type operation member for providing a trigger for shooting. Shooting is performed by sliding the power switch  107  to turn on the digital still camera  100 , rotating the recording mode dial  108  to determine a recording mode, rotating the drive mode lever  109  to determine a drive mode, and pressing the shutter button  110 . The shutter button  110  is an important operation member for providing a trigger for shooting, and the operability of the shutter button  110  greatly affects the usability of the digital still camera  100 . Thus, the shutter button  110  which is considerably larger than the menu button  111  is used. 
     The menu button  111  is a button-type operation member for changing other setting items. When the menu button  111  is pressed, setting items are displayed on a liquid crystal monitor (not shown) provided on the back of the digital still camera  100 . The setting items displayed on the liquid crystal monitor upon press of the menu button  111  include a size of an image to be recorded, white balance, ISO sensitivity, an operating mode of auto-focus, a light emission mode of the pop-up electronic flash  106 , and so on. These setting items cannot be changed by rotating the recording mode dial  108  or rotating the drive mode lever  109 . However, the frequency of changing the setting item is low, and thus a button-type operation member which is relatively small is adopted for the menu button  111 . 
     2. Composite Rotary Switch 
       FIG. 4  is an exploded perspective view of the top surface of the digital still camera  100  including a composite rotary switch.  FIG. 5  is a cross-sectional view of the top surface of the digital still camera  100 .  FIG. 5  shows an A-A cross section of  FIG. 25 . 
     The composite rotary switch according to the present embodiment includes the recording mode dial  108 , a detector  117  for electrically detecting a rotational position of the recording mode dial  108 , the drive mode lever  109 , and a detector  109   c  and  118  for optically detecting a rotational position of the drive mode lever  109 . 
     2.1 Composite Rotary Switch Mounting Section 
     A composite rotary switch mounting section  113  is formed on a top surface cover  112  of the digital still camera  100 . The composite rotary switch mounting section  113  includes a recess  113   a  on which the drive mode lever  109  is placed, a cylindrical member  113   b  which is inserted through a circular opening  109   a  of the drive mode lever  109 , a pair of stoppers  113   c  which are inserted into a pair of fan-shaped openings  109   b  of the drive mode lever  109 , a pair of light flux passing portions  113   d  that allow light flux which is emitted from a pair of reflective photo-couplers  118  and is reflected by a pair of reflector plates  109   c  bonded to the back side of the drive mode lever  109  to pass through the light flux passing portion  113   d , and a rotating shaft hole  113   e  that allows a rotating shaft  115  providing the rotational center of the recording mode dial  108  to be inserted through the rotating shaft hole  113   e.    
     2.2 Recording Mode Dial 
     The recording mode dial  108  is fixed to the rotating shaft  115  which is inserted through a rotor coupling plate  114  and the rotating shaft hole  113   e . The rotor coupling plate  114  has functions of preventing the recording mode dial  108  from dropping out of the rotating shaft  115 , and of coupling the recording mode dial  108  to a rotary switch rotor  116 . A groove is made at the lower portion of the rotor coupling plate  114 , which engages with the convex part of the rotary switch rotor  116 . A rotating portion  117   a  of a rotary switch  117  also has a groove cut therein, and the groove engages with the rail  116   a  provided at the center of the rotary switch rotor  116 . The rotary switch rotor  116  is configured to be able to absorb an error for alignment among the recording mode dial  108 , the rotor coupling plate  114 , and the rotary switch  117  mounted on a switch board  119 . 
     Therefore, when the recording mode dial  108  is rotated, the rotating portion  117   a  of the rotary switch  117  rotates. The rotary switch  117  is a switch capable of electrically detecting a rotation angle of the rotating portion  117   a . The rotary switch  117  is mounted on the switch board  119 . The switch board  119  is connected to a main board (not shown) by a flexible cable (not shown). A CPU mounted on the main board can recognize the recording mode which is selected by the recording mode dial  108 , by electrically detecting a rotation angle of the rotating portion  117   a  of the rotary switch  117 . 
     Note that the structure of the recording mode dial  108  described above is one example and is not limited thereto. The recording mode dial  108  can have any structure as long as it is an electrical position detector that can electrically detect a rotational position (indicated position) of the rotary operation member. 
     2.3 Drive Mode Lever 
     The drive mode lever  109  is inserted through the cylindrical member  113   b  and is placed in the recess  113   a . The drive mode lever  109  is provided under the recording mode dial  108  and has a knob  109   d  protruding from an outer edge of the recording mode dial  108 . In addition, the rotatable range of the drive mode lever  109  is regulated by a pair of stoppers  113   c  inserted through a pair of fan-shaped openings  109   b . For the above-described reasons, the drive mode lever  109  is referred to as “lever” but does not essentially differ from “dial”. 
     A pair of reflector plates  109   c  are bonded to the back side of the drive mode lever  109 . A light flux emitted from a pair of reflective photo-couplers  118  mounted on the switch board  119  passes through a pair of light flux passing portions  113   d  provided on the top surface cover  112  to reach the back side of the drive mode lever  109 . 
     The position of each reflector plate  109   c  changes depending on the rotational position of the drive mode lever  109 . When the reflector plate  109   c  is positioned at the position which a light flux emitted from the reflective photo-coupler  118  reaches, the light flux emitted from the reflective photo-coupler  118  is reflected by the reflector plate  109   c , passes again through the light flux passing portion  113   d  provided in the top surface cover  112 , and then reaches light-receiving portion of the reflective photo-coupler  118 . On the other hand, when the reflector plate  109   c  is not positioned at the position which a light flux emitted from the reflective photo-coupler  118  reaches, the light flux Emitted from the reflective photo-couplers  118  does not reach the light-receiving portions of the reflective photo-couplers  118 . Thus, the CPU mounted on the main board can recognize a drive mode selected by the drive mode lever  109 , by monitoring outputs from the pair of reflective photo-couplers  118 . 
     Note that the structure of the drive mode lever  109  described above is one example and is not limited thereto. The drive mode lever  109  can have any structure as long as it is an optical position detector that can optically detect a rotational position of (position indicated by) the rotary operation member. Also, it is not necessary to regulate the rotatable range. 
     2.4 Encoder of Drive Mode Lever 
       FIG. 6  is a diagram of the drive mode lever  109  as seen from a top surface thereof, in which the recording mode dial  108  is being removed.  FIG. 7  is a diagram showing a correspondence between a state of reflection detection of the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ), and the drive mode. 
     In  FIG. 6 , one end of each fan-shaped opening  109   b  of the drive mode lever  109  contacts on a stopper  113   c . Therefore, the drive mode lever  109  cannot be further rotated counterclockwise. The state shown in  FIG. 6  corresponds to state  1  shown in  FIG. 7 . Namely, the reflective photo-coupler  118 ( 1 ) detects “reflection” but the reflective photo-coupler  118 ( 2 ) detects “no reflection”. This is because although the reflector plate  109   c ( 1 ) is positioned at a position of the drive mode lever  109 , corresponding to the reflective photo-coupler  118 ( 1 ), the reflector plate  109   c ( 2 ) is not positioned at a position of the drive mode lever  109 , corresponding to the reflective photo-coupler  118 ( 2 ). The CPU mounted on the main board can recognize that a single shooting mode is selected by the drive mode lever  109 , by monitoring the outputs from the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ). 
     When the drive mode lever  109  is rotated clockwise by a constant amount from the state shown in  FIG. 6 , State  2  shown in  FIG. 7  is set. In State  2  shown in  FIG. 7 , both of the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ) detect “reflection”. This is because the reflector plate  109   c ( 2 ) is also positioned at the position of the drive mode lever  109 , corresponding to the reflective photo-coupler  118 ( 2 ). The CPU mounted on the main board can recognize that a continuous shooting mode is selected by the drive mode lever  109 , by monitoring the outputs from the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ). 
     When the drive mode lever  109  is further rotated clockwise by a constant amount, State  3  shown in  FIG. 7  is set. In State  3  shown in  FIG. 7 , the reflective photo-coupler  118 ( 1 ) does not detect reflection but the reflective photo-coupler  118 ( 2 ) detects reflection. This is because the reflector plate  109   c ( 1 ) is not positioned at the position of the drive mode lever  109  corresponding to the reflective photo-coupler  118 ( 1 ). The CPU mounted on the main board can recognize that an auto bracket mode is selected by the drive mode lever  109 , by monitoring the outputs from the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ). When the drive mode lever  109  is further rotated clockwise by a certain amount, State  4  shown in  FIG. 7  is set. In this state, the other end of each fan-shaped opening  109   b  of the drive mode lever  109  contacts on a corresponding stopper  113   c . Therefore, the drive mode lever  109  cannot be further rotated clockwise. In State  4  shown in  FIG. 7 , both of the reflective photo-couplers  118 ( 1 ), ( 2 ) do not detect reflection. This is because the reflector plate  109   c ( 2 ) is not positioned either in the position of the drive mode lever  109  corresponding to the reflective photo-coupler  118 ( 2 ). The CPU mounted on the main board can recognize that a self-timer mode is selected by the drive mode lever  109 , by monitoring the outputs from the reflective photo-couplers  118 ( 1 ) and  118 ( 2 ). 
     As described above, the CPU mounted on the main board can recognize a drive mode selected by the drive mode lever  109 , by monitoring the outputs from the pair of reflective photo-couplers  118 ( 1 ) and  118 ( 2 ). 
     By using the pair of reflective photo-couplers  118 ( 1 ) and  118 ( 2 ), four states can be recognized. But if the number of states to be recognized is two, only one reflective photo-coupler may be used. Even if the number of states to be recognized is five or more, such a situation can be handled by appropriately increasing the number of reflective photo-couplers. 
     Furthermore, although, in the digital still camera according to the present embodiment, the pair of reflective photo-couplers  118 ( 1 ) and  118 ( 2 ) are arranged to be symmetrical about the rotational center, the arrangement of the reflective photo-couplers is not limited thereto. Reflective photo-couplers may be arranged on a plurality of concentric circles having different diameters, respectively, with the rotational center being the center of the concentric circles. 
     For the optical position detector, a photointerrupter, and so on can also be used, instead of or in addition to a reflective photo-coupler. When a photointerrupter is used, it may be configured, for example, that a shielding portion is provided on a part of the drive mode lever  109  so that a state in which the shielding portion shields between a light-emitting section and a light-receiving section of the photointerrupter and a state in which the shielding portion does not shield between the light-emitting section and the light-receiving section are created by rotating the drive mode lever  109 . When the shielding portion of the drive mode lever  109  is formed in a direction toward the rotational center, the area in which the composite rotary switch is mounted does not increase compared to the case of using reflective photo-couplers. In addition, there is no need to bond the reflector plate  109   c  to the back side of the drive mode lever  109 . 
     3. Summary 
     A composite rotary switch according to the present embodiment includes the recording mode dial  108  rotatable around a rotational center, the drive mode lever  109  rotatable around the rotational center, the rotary switch  117  that electrically detects a rotational position of the recording mode dial  108 , and the reflector plates  109   c  and the reflective photo-couplers  118  that optically detect a rotational position of the drive mode lever  109 . The composite rotary switch includes two operation members (the recording mode dial  108  and the drive mode lever  109 ) and implements a plurality of switch functions. 
     As described above, in the present embodiment, a rotational position of an operation member which is the drive mode lever  109  arranged to be stacked on the recording mode dial  108  is detected using an optical detector such as a photo-coupler. Generally, a rotary operation member has a structure to detect a rotational position thereof by using an electric contact formed of a brush, a conductor, and so on. Therefore, when a plurality of operation members are stacked and arranged, it needs to prevent a region of an electric contact of one operation member from being overlapped on a region of an electric contact of the other operation member. Hence, the electric contact region of one operation member needs to be arranged around the electric contact region of the other operation member, causing a problem, that the structure becomes large. In contrast to this, in the structure in the present embodiment, a rotational position of one operation member is detected using an optical detector (photo-coupler), which eliminates the need to arrange components around the other operation member. Accordingly, the number of components can be reduced and the structure of the operation members can be miniaturized. Hence, even in a small region where it is difficult to arrange more new operation members, operation members having a plurality of switch functions can be arranged. Furthermore, an optical detector performs detection in a noncontact manner and thus is superior in terms of reliability to an electrical detector that performs detection in a contact manner. 
     INDUSTRIAL APPLICABILITY 
     The present embodiment enables to miniaturize a rotary switch having a plurality of switch functions and arrange the rotary switch even in a small region. Thus, the concept of the present embodiment is useful in, for example, a digital still camera which is small in size and requires a numbers of operation members.