JP6331310B2 - Cam drive mechanism control device and cam drive mechanism control method - Google Patents

Description

  The present invention relates to a control device for a cam drive mechanism and a control method therefor.

  2. Description of the Related Art A driving mechanism that rotates a cam member by a motor and controls an operation of a driving target by a cam surface formed on the cam member is widely used. For example, in a single-lens reflex camera with a built-in quick return mirror, a cam member is rotated by the driving force of a motor that is a driving source, and a member having a cam follower (hereinafter referred to as a driven member) is operated by the cam surface of the cam member. The mirror up / down operation of the mirror drive mechanism and the shutter charge operation of the shutter charge mechanism are controlled to be performed at a predetermined timing.

  As this type of cam member, there are known an end face cam having a cam surface at an end face portion in a direction along the rotation axis, and a circumferential cam in which a cam surface is formed on a circumference surrounding the rotation axis. In any form of cam member, the cam surface is a region where the cam follower of the driven member is pushed in accordance with the rotation of the cam member (in the case of an end face cam, an inclination that increases the amount of protrusion in the rotation axis direction as the rotation proceeds) In the case of a region or circumferential cam, an inclined region that increases the amount of protrusion in the direction away from the rotation axis as it advances in the rotation direction, and a region that goes in the direction opposite to the direction in which the cam follower is pushed in as it advances in the rotation direction (end cam) If there is, an inclined region that reduces the amount of protrusion in the direction of the rotation axis as it proceeds in the rotation direction, and an inclined region that approaches the rotation axis as it proceeds in the direction of rotation in the case of the circumferential surface cam are included. Here, the former area is called a pressing cam area, and the latter area is called a relief cam area. In the pressing cam area, the cam follower is pressed against the load, and when the contact object of the cam follower is switched to the escape cam area, the action of the load on the cam surface is reversed. Due to the load fluctuation on the cam surface, a speed difference may occur during rotation of the cam member, and the rotation speed of the cam member may be higher than expected in a state where the escape cam region is used. In particular, when the driven member is urged in a direction in which the cam follower is brought into contact with the cam surface, the urging force acts as an assist torque in the direction of pushing the escape cam region and advancing the cam member. The tendency is strengthened. If the rotation of the cam member becomes faster, the operating speed of the driven system including the driven member becomes faster than that assumed by the cam curve, and the impact acting on the driven system may increase. For example, in a mirror drive mechanism of a single-lens reflex camera, the mirror bound increases when the mirror-up and mirror-down operations are completed, which is a restriction on the imaging frame speed-up. Also, if the cam member's rotational speed is high and the cam surface's escape cam region has a large inclination angle (the amount of displacement given to the cam follower per unit rotation angle of the cam member), the cam follower cannot follow the cam surface. There is also a possibility of being separated instantaneously.

  As a measure for preventing such a malfunction in the relief cam region, it is conceivable to reduce the inclination of the relief cam region. However, if the inclination of the relief cam region is reduced, there arises a problem that the cam member becomes large and that the cam member deviates from an ideal cam curve. As another solution, there is known a method in which the motor is reversely driven or stopped at a timing at which a load is no longer applied to the cam member to perform braking (Patent Document 1).

JP-A-5-69600

  As in Patent Document 1, when the brake is applied by the motor when the used portion of the cam surface is switched to the relief cam region, the rotational speed of the cam member becomes too slow and the operation of the driven system is delayed from the expected timing. There is a problem. For example, when applied to a mirror driving mechanism of a single-lens reflex camera, there is a possibility that the speed of the mirror-up operation or the mirror-down operation is reduced and the specs of the photographing frame speed are reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device and a control method for a cam drive mechanism that suppresses a change in the speed of a cam member due to a load change and is excellent in operation performance. To do.

The present invention relates to a motor, a rotating cam member having a cam surface and rotated by a driving force of the motor, a driven member having a cam follower in contact with the cam surface, a support member not rotated by the motor, and a rotating cam member. The present invention relates to an apparatus and a method for controlling a cam driving mechanism including a code plate provided on the other side of the support plate and a brush provided on the other of the support member and the rotating cam member and having a terminal that contacts a contact on the code plate . The rotating cam member is rotated by a one-way rotational drive of the motor, and the cam surface of the rotating cam member has an inclined pressing cam region that presses the cam follower against a load by the rotation of the rotating cam member, and a pressing cam region. The cam surface includes a relief cam region in a reverse inclination direction.

In the aspect of the control device of the present invention, the rotating cam member is rotated by one-way rotational driving of the motor, and when the rotating cam member is in a rotational direction position where the escape cam region and the cam follower face each other, the pressing cam region and the cam follower are Motor control means for changing the rotation speed of the motor when there is a rotary cam member at the opposite rotational direction position. The motor control means is connected to the contact between the brush terminal and the code plate by the rotation of the rotary cam member. receiving a signal representing a change in a change in the rotational speed at the time of driving the motor, Ru to perform the driving stop of the motor.

In the aspect of the control method of the present invention, when the rotary cam member is in a rotational direction position facing the pressing cam region and the cam follower, the motor is driven to rotate in one direction at a predetermined speed to rotate the clearance cam region and the cam follower. When there is a rotating cam member in the direction position, the motor is driven to rotate in one direction at a speed different from a predetermined speed, and a signal representing a change in the conduction relationship between the brush terminal and the code plate contact due to the rotation of the rotating cam member is generated. receiving by the switching of the rotational drive of the rotary drive and the predetermined speed different from the speed at a given speed of the motor, and a drive stop of the motor intends row.

In either aspect of the control device and the control method, when there is a rotating cam member at a rotational position where the relief cam area and the cam follower face each other, and when there is a rotating cam member at a rotational position where the pressing cam area and the cam follower face each other It is characterized in that the motor is driven to rotate at a reduced speed.

  The rotation speed of the motor can be changed by changing the duty ratio of the motor drive pulse waveform or by changing the motor drive voltage. The duty ratio can be changed by changing the time width of energization and non-energization of the motor in the cycle or setting the time width for short-circuiting the motor terminals in the cycle.

  In the case of the control for changing the duty ratio, it is preferable that the duty ratio when the rotary cam member is in the rotational direction position where the relief cam region and the cam follower face each other is smaller than 50%.

The present invention is particularly effective in a configuration in which a biasing force that presses the cam follower against the cam surface acts on the driven member. When the pressing cam area of the cam surface presses the cam follower, a load against the rotation of the rotating cam member is applied by the urging force against the driven member. On the other hand, when the cam follower is opposed to the relief cam region of the cam surface by the urging force against the driven member, the assist torque in the rotational direction of travel of the rotary cam member acts. That is, the load fluctuation to the rotating cam member is increased by the urging force to the driven member, but the fluctuation of the rotating speed of the rotating cam member can be suppressed by controlling the rotating speed of the motor according to the present invention.

According to the control device and the control method of the cam drive mechanism according to the present invention, it is assumed that the speed change of the cam member due to the load fluctuation is suppressed by changing the rotation speed of the motor according to the load fluctuation to the rotating cam member. Driving can be performed with a cam curve. In particular, while the escape cam area and the cam follower face each other, the motor is driven at a reduced speed instead of a brake such as motor reverse rotation or motor stop, thereby preventing the rotation cam member from being accelerated and preventing an excessive decrease in the rotation speed. The cam drive mechanism can have excellent operation performance. In addition, by receiving a signal from a code plate and a brush that can detect the rotational position of the rotating cam member, the rotational speed of the rotating cam member is changed by changing the motor rotating speed when the motor is driven and stopping the driving of the motor. Can be controlled with higher accuracy.

It is a figure which shows the outline of the optical system of the single-lens reflex camera provided with the control apparatus of the cam drive mechanism to which this invention is applied. It is a perspective view which shows the mirror down state of the mirror drive mechanism provided in a single-lens reflex camera. It is a front view of the mirror down state of the mirror drive mechanism. It is a top view of the mirror down state of the mirror drive mechanism. It is a side view of the mirror down state of the mirror drive mechanism. It is a side view which shows a part of mirror drive mechanism in a mirror down state. It is a side view which shows a part of mirror drive mechanism in a mirror up state. It is the perspective view which looked at the end cam gear which constitutes a mirror drive mechanism from the lower part. It is sectional drawing of an end surface cam gear and its support part. It is the figure which looked at the code | cord board which detects the rotation direction position of an end surface cam gear from the lower side. It is a timing chart figure which shows the relationship between the unfolding shape and rotation direction position detection of an end surface cam gear, and drive control of a motor. It is a block diagram which shows the connection relation of the electrical component which comprises a mirror drive mechanism.

  Hereinafter, a control device and a control method for a cam drive mechanism according to the present invention will be described with reference to an embodiment applied to a single-lens reflex camera. A single-lens reflex camera (hereinafter referred to as a camera) 10 shown in FIG. 1 has a lens mount 13 for attaching / detaching an interchangeable lens barrel 12 on the front surface of a camera body 11, and a mirror box 14 is provided inside the camera body 11. ing. A movable mirror (quick return mirror) 15 is provided in the mirror box 14. As shown in FIGS. 2 and 5, the movable mirror 15 has a structure in which a sub mirror holding frame 18 that supports the sub mirror 19 is rotatably supported on the back side of the main mirror holding frame that supports the main mirror 17. The main mirror holding frame 16 is pivotally supported by a pair of main mirror hinges 16x (FIGS. 1, 5 to 7) provided on both side walls of the mirror box. A focal plane shutter (hereinafter referred to as shutter) 20 is provided behind the movable mirror 15, and an image sensor 21 is provided behind the shutter 20. The shutter 20 is composed of a front curtain and a rear curtain, and subject light is passed to the image sensor 21 side by running the front curtain and the rear curtain at a predetermined time difference by a shutter drive unit (not shown). Note that the camera 10 of the present embodiment is a digital camera that uses the image sensor 21 as an imaging light-receiving medium, but can also be applied to a camera that uses a silver salt film as the imaging light-receiving medium.

  In the following description, with the lens barrel 12 attached to the lens mount 13, the direction along the optical axis O of the imaging optical system from the photographing lens 12 a in the lens barrel 12 to the image sensor 21 is the front-rear direction of the camera 10. The object side is the front and the image sensor 21 side is the rear. The main mirror hinge 16x extends in a direction orthogonal to the optical axis O, and the extending direction of the main mirror hinge 16x is the left-right direction (horizontal width direction) of the camera 10. Further, when the camera 10 is viewed from the front as shown in FIG. 3, the direction of the displacement (movement locus) of a predetermined location on the movable mirror 15 when the movable mirror 15 is rotated about the main mirror hinge 16x as an axis is shown in FIG. 10 vertical direction. That is, the axis extending in the front-rear direction of the camera 10, the axis extending in the left-right direction, and the axis extending in the up-down direction are orthogonal to each other.

  The movable mirror 15 is inclined down at an angle of about 45 degrees with respect to the optical axis O on the optical path in front of the shutter 20 with the main mirror hinge 16x as an axis (solid line in FIG. 1, FIGS. 2 to 6). ) And the up position retracted from the optical path in front of the shutter 20 (two-dot chain line in FIG. 1, FIG. 7). The vertical direction in the camera 10 has been defined previously. Of these vertical directions, the direction toward the up position of the movable mirror 15 is upward, and the direction toward the down position of the movable mirror 15 is downward. As shown in FIG. 1, FIG. 5 and FIG. 6, a down positioning protrusion 25 protrudes from the inner surface of one (left side when viewed from the front) of both side walls of the mirror box 14 positioned with the movable mirror 15 in between. By bringing one side near the tip of the main mirror holding frame 16 into contact with the down positioning protrusion 25, the down position of the movable mirror 15 is determined. The down positioning protrusion 25 can finely adjust the mounting position with respect to the mirror box 14. In the mirror box 14, a mirror-up cushioning material 26 (FIGS. 1, 2, and 7) that can contact the upper surface of the main mirror holding frame 16 when the movable mirror 15 is rotated to the up position. Is provided.

  As shown in FIG. 1, a pentaprism 22 is held above the movable mirror 15, and an eyepiece lens 23 is provided behind the emission surface of the pentaprism 22. The pentaprism 22 and the eyepiece lens 23 constitute a finder optical system. Subject light that enters the mirror box 14 through the photographing lens 12a in the lens barrel 12 is reflected upward by the main mirror 17 and enters the pentaprism 22 when the movable mirror 15 is in the down position. And the subject image can be observed through the eyepiece 23. In this state, photometry can be performed by the photometry unit 27 provided behind the pentaprism 22. In the down position of the movable mirror 15, the sub mirror 18 protrudes obliquely downward with respect to the main mirror 17, and a part of the subject light is guided to the distance measuring unit 28 below the mirror box 14 by the sub mirror 18. The distance can be detected.

  On the other hand, when the movable mirror 15 is in the up position, the subject light incident into the mirror box 14 through the photographing lens 12a is not reflected by the main mirror 17 but proceeds to the shutter 20 side, and the shutter 20 is opened to open the image sensor 21. Light can be incident on the light receiving surface. At the up position of the movable mirror 15, the sub mirror 18 is stored on the back side of the main mirror holding frame 16. An LCD monitor 29 provided on the rear surface of the camera body can display an electronic image of the subject obtained by the image sensor 21 and various types of information other than the electronic image.

  With reference to FIG. 2 and subsequent figures, the details of the mirror drive mechanism 40 for moving the movable mirror 15 up and down will be described. The mirror drive mechanism 40 is provided along one side of the mirror box 14 (left side when viewed from the front), and a deceleration that transmits the drive force of the mirror drive motor 41 and the rotation output shaft 41a of the mirror drive motor 41. A gear train 42, an end face cam gear (rotary cam member) 43 to which rotational driving force is transmitted via the reduction gear train 42, and a slider (driven member) 44 whose position is controlled by the end face cam gear 43 are provided. When viewed from the front as shown in FIG. 3, the mirror drive motor 41 is located away from the mirror box 14 and the slider 44 is located along the side of the mirror box 14 and is separated in the left-right direction. The reduction gear train 42 and the end face cam gear 43 are arranged above the slider 41 and the slider 44. The mirror drive motor 41 is driven and controlled by a control circuit (motor control means) 55 (FIG. 12) provided in the camera 10.

  The mirror drive motor 41 is disposed with the longitudinal direction thereof directed in the vertical direction, and the rotation output shaft 41a protrudes upward. A pinion 41b is supported on the rotation output shaft 41a, and the rotation output shaft 41a and the pinion 41b rotate integrally. The reduction gear train 42 includes a first reduction gear 42a, a second reduction gear 42b, and an idle gear 42c. Each gear constituting the reduction gear train 42 and the end face cam gear 43 are respectively connected to a rotation output shaft 41a of the mirror drive motor 41. The shaft is supported so as to be rotatable around a parallel (that is, vertically) rotating shaft. The first reduction gear 42a and the second reduction gear 42b are two-stage gears consisting of a large-diameter gear and a small-diameter gear that are coaxially positioned, and the pinion 41b meshes with the large-diameter gear of the first reduction gear 42a. The small diameter gear of the first reduction gear 42a meshes with the large diameter gear of the second reduction gear 42b, and the small diameter gear of the second reduction gear 42b meshes with the idle gear 42c. As shown in FIGS. 3 and 4, the reduction gear train 42 is arranged so as to fill a space between the pinion 41 b and the end face cam gear 43 that are separated in the left-right direction.

  As shown in FIG. 8, the end face cam gear 43 has a cylindrical cam portion 43b below the gear portion 43a that meshes with the idle gear 42c. The cylindrical cam portion 43b is formed with an end cam 43c facing downward. The end cam 43c is positioned farthest from the gear portion 43a and has a down holding surface C1 (a large amount of protrusion in the axial direction) and a gear. A spiral up cam surface (relief cam region) C2 and a down cam surface (pressing cam region) C4 are located between the up allowable surface C3 located close to the portion 43a (the amount of protrusion in the axial direction is small). It is the form connected by. As can be seen from the developed shape of the end face cam 43c shown in the upper part of FIG. 11, each of the down holding surface C1 and the up allowable face C3 is a plane substantially orthogonal to the rotation axis of the end face cam gear 43, and the up cam face C2 is The cam surface is steeper than the down cam surface C4 (the axial displacement per unit rotation angle of the end face cam gear 43 is large). A slant connection surface CM2 that gradually loosens the inclination from the up cam surface C2 is formed at a connection portion of the up cam surface C2 to the up allowable surface C3.

The reduction gear train 42 and the end face cam gear 43 are supported on a mirror drive gear block case 72 (a part of which is shown in FIG. 9) fixed to the mirror box 14, and a mirror drive gear block cover (support member) 73 ( 9 is partially held in FIG. 9 from above. The mirror drive gear block cover 73 is fixedly supported on the mirror drive gear block case 72 and is not rotated by the driving force of the mirror drive motor 41. The mirror drive motor 41 is also fixed to the mirror drive gear block case 72. FIG. 9 shows a holding portion of the end cam gear 43 by the mirror drive gear block case 72 and the mirror drive gear block cover 73. The end face cam gear 43 is rotatably supported by inserting a fixed shaft 72b projecting on a bottom wall portion 72a forming a part of the mirror drive gear block case 72 into the shaft hole 43d, and a mirror drive gear block cover. The upper wall portion 73a that forms a part of 73 is prevented from coming off from the fixed shaft 72b.

  As shown in FIGS. 4 and 9, the brush 50 is fixed to the upper surface of the end cam gear 43. A code plate 54 is attached to the mirror drive gear block cover 73 at a position facing the brush 50. The code plate 54 is electrically connected to the control circuit 55 (FIG. 12), and the rotational position of the end cam gear 43 can be detected by the contact relationship between the brush 50 and the code plate 54.

  FIG. 10 shows details of the code plate 54. The code plate 54 has a ground contact 54a, a mirror down contact 54b, and a mirror up contact 54c. Further, a front contact 54d that conducts to the mirror down contact 54b and a front contact 54e that conducts to the mirror up contact 54c are formed. In FIG. 10, these contact points are hatched for easy identification. The ground contact 54a has an annular shape that continues in the circumferential direction around the rotation axis of the end face cam gear 43. The mirror down contact 54b, the mirror up contact 54c, the front contact 54d, and the front contact 54e are outside the ground contact 54a. Are arranged at different positions in the circumferential direction. The brush 50 selectively contacts the inner peripheral terminal 50a that is always in contact with the ground contact 54a and the mirror down contact 54b, the mirror up contact 54c, the front contact 54d, and the front contact 54e according to the rotational position of the end cam gear 43. And an outer peripheral side terminal 50b. In a state where the outer peripheral side terminal 50b of the brush 50 is in contact with the mirror down contact 54b, ON of the mirror down switch (FIG. 11) is input to the control circuit 55, and the outer peripheral side terminal 50b of the brush 50 is in contact with the mirror up contact 54c. In the state, ON of the mirror up switch (FIG. 11) is input to the control circuit 55.

  The mirror drive motor 41 is a DC motor that can drive the rotation output shaft 41a to rotate forward and backward, and the end cam gear 43 makes one reciprocation of the movable mirror 15 during one rotation by the mirror drive motor 41. It is the one rotation cam gear which performs the raising / lowering operation of. The rotation direction of the end face cam gear 43 when the mirror drive motor 41 is driven to rotate forward is indicated by an arrow V1 in FIG. The mirror-down contact 54b and the mirror-up contact 54c of the code plate 54 are edges E1 and E3 positioned in the front in the rotation traveling direction (V1) of the end face cam gear 43 and edges E2 and E4 positioned in the rear in the rotation traveling direction, respectively. have. That is, the mirror-down contact 54b is formed in the rotation direction range from the edge E1 to the edge E2, and the mirror-up contact 54c is formed in the rotation direction range from the edge E3 to the edge E4. The rotational direction range from the edge E1 to the edge E2 (formation range of the mirror down contact 54b) is the down region U1, the rotational direction range from the edge E2 to the edge E3 is the up transition region U2, and the rotational direction range from the edge E3 to the edge E4 Is referred to as up region U3, and the rotational direction range from edge E4 to edge E1 is referred to as down transition region U4.

  Near the side surface of the mirror box 14, a first guide shaft 47 and a second guide shaft 48 are extended in the up-down direction at different positions in the front-rear direction. The upper and lower ends of the first guide shaft 47 are fixedly supported with respect to the mirror box 14, and the upper and lower ends of the second guide shaft 48 are also fixedly supported with respect to the mirror box 14. In this fixed state, the first guide shaft 47 and the second guide shaft 48 are extended in parallel to each other.

  The slider 44 is configured by elastically coupling the first slider 45 and the second slider 46 with a slider coupling spring 53. As shown in FIGS. 6 and 7, the first slider 45 includes a side plate portion 45a that faces the side surface of the mirror box 14, and a lower wall portion 45b that protrudes in a direction away from the mirror box 14 with respect to the side plate portion 45a. An upper wall 45c and a connection wall 45d are provided. The lower wall portion 45b and the upper wall portion 45c are spaced apart from each other in the vertical direction and extend in the front-rear direction. The lower wall portion 45b and the front portion of the upper wall portion 45c are connected by a connection wall portion 45d. Yes. That is, the lower wall portion 45b, the upper wall portion 45c, and the connection wall portion 45d form a U-shaped frame portion that is opened rearward. Guide holes 45e and 45f (FIGS. 6 and 7) through which the first guide shaft 47 is slidably inserted are formed in the lower wall portion 45b and the upper wall portion 45c, and the first slider 45 extends along the first guide shaft 47. It is guided so that it can move straight up and down. A mirror pressing portion 45g is provided at the tip of the lower wall portion 45b. The mirror pressing portion 45g has a bifurcated shape sandwiching the second guide shaft 48, and the rotation of the first slider 45 around the first guide shaft 47 is restricted by the engagement of the mirror pressing portion 45g and the second guide shaft 48.

  The first slider 45 is further provided with a spring hooking arm 45h protruding forward of the lower wall 45b, and a first mirror up spring (biasing means) 51 and a second mirror up spring ( Each lower end portion of the biasing means) 52 is engaged. The upper ends of the first mirror up spring 51 and the second mirror up spring 52 are engaged with a spring hook (not shown) provided in the mirror box 14. The first mirror up spring 51 and the second mirror up spring 52 are tension springs, and move and bias the first slider 45 upward. In addition, a rear wall portion 45i positioned behind the connection wall portion 45d with the upper wall portion 45c interposed therebetween is formed on the upper portion of the first slider 45, and the side plate portion 45a, the upper wall portion 45c, the connection wall portion 45d, and the rear side. A cylindrical spring holding portion opened downward is formed by the wall 45i.

A cam follower 45j located behind the rear wall 45i projects from the upper portion of the side plate 45a of the first slider 45. The upper end of the cam follower 45j is at a position facing the end face cam 43c of the end face cam gear 43 (FIGS. 2 and 5), and the urging force of the first mirror up spring 51 and the second mirror up spring 52 causes the cam follower 45j to act on the end face cam 43c. It acts in the direction of contact ( the direction of pressing) . As shown in FIGS. 5 to 7, the cam follower 45j is located between the first guide shaft 47 and the second guide shaft 48 in the front-rear direction. The cam follower 45j is formed as a protrusion having a longitudinal direction in a direction parallel to the axis of the first guide shaft 47 or the second guide shaft 48. The contact portion of the cam follower 45j with the end face cam 43c is vertically moved between the up cam face C2 and the down cam face C4 according to the rotation of the end face cam gear 43 (the first guide shaft 47 and the second guide). The shape is such that a pressing force in the direction parallel to the axis of the shaft 48 is generated. 11 shows the relative position change of the cam follower 45j with respect to the end face cam 43c when the end face cam gear 43 is rotated. In FIG. 11, the cam follower 45j is schematically represented in a circular shape. Yes.

  The second slider 46 is located in a space surrounded by the side plate part 45a, the lower wall part 45b, the upper wall part 45c, and the connection wall part 45d of the first slider 45, and guides the first guide shaft 47 to be slidably inserted. A hole 46a (FIGS. 6 and 7) is formed. Guide protrusions 46b (FIGS. 6 and 7) project from the second slider 46 upward, and the guide holes 46a penetrate from the bottom surface of the second slider 46 to the guide protrusions 46b. Similar to the first slider 45, the second slider 46 is guided along the first guide shaft 47 so as to be able to move straight up and down. The second slider 46 is provided with a bifurcated mirror pressing portion 46 c sandwiching the second guide shaft 48, and a second centering on the first guide shaft 47 by the engagement of the mirror pressing portion 46 c and the second guide shaft 48. The rotation of the slider 46 is restricted.

  A slider coupling spring 53 is inserted between the upper wall portion 45 c of the first slider 45 and the upper surface of the second slider 46. The slider coupling spring 53 is a compression spring in which the first guide shaft 47 is inserted inside, the guide protrusion 46 b is inserted into the inner peripheral portion on the lower end side, and the outer peripheral portion on the upper end side is the spring of the first slider 45. By being inserted into the holding part (the part surrounded by the side plate part 45a, the upper wall part 45c, the connection wall part 45d, and the rear wall part 45i), it can expand and contract in the axial direction without buckling. The slider coupling spring 53 urges the second slider 46 in a direction to contact the lower wall portion 45b of the first slider 45, and the first slider 45 and the second slider 46 are elastically coupled by this urging force. The slider 44 is configured. The slider 44 is moved and urged upward by the urging force of the first mirror up spring 51 and the second mirror up spring 52 as a whole. The urging force of the slider coupling spring 53 is set to be stronger than the urging force of the first mirror up spring 51 and the second mirror up spring 52 combined. In this embodiment, the two springs of the first mirror up spring 51 and the second mirror up spring 52 are provided. However, the slider 44 may be urged to move upward by a single spring.

  On one side of the main mirror holding frame 16, a mirror sheet boss 16 a that protrudes in a direction approaching the slider 44 is provided at a position close to the mirror sheet hinge 16 x. The mirror sheet boss 16a has a cylindrical outer surface shape. The mirror pressing portion 45g of the first slider 45 and the mirror pressing portion 46c of the second slider 46 are opposed to each other in the vertical direction with the mirror sheet boss 16a interposed therebetween, and the mirror pressing portion 45g is located below the mirror sheet boss 16a. 46c is located above the mirror sheet boss 16a. The first slider 45 and the second slider 46 can move relative to each other in the vertical direction, and the distance between the mirror pressing portion 45g and the mirror pressing portion 46c changes according to the relative movement. As shown in FIG. 7, the distance between the mirror pressing portion 45g and the mirror pressing portion 46c becomes the smallest when the lower surface of the second slider 46 is in contact with the lower wall portion 45b of the first slider 45 by the biasing force of the slider coupling spring 53. In this case, the minimum distance between the mirror pressing portion 45g and the mirror pressing portion 46c is set slightly larger than the diameter of the mirror sheet boss 16a. The difference between the minimum distance between the mirror pressing portion 45g and the mirror pressing portion 46c and the diameter of the mirror sheet boss 16a is referred to as the minimum clearance M1.

  The slider 44 operates the movable mirror 15 by moving in the vertical direction. When the slider 44 moves downward and the mirror pressing portion 46c presses the mirror sheet boss 16a downward, the movable mirror 15 is rotated toward the down position, and the slider 44 moves upward and the mirror pressing portion 45g is moved. The movable mirror 15 is rotated toward the up position by pressing the mirror sheet boss 16a upward.

  The operation of the mirror drive mechanism 40 having the above configuration will be described. The rotational drive direction of the mirror drive motor 41 that rotates the end face cam gear 43 in the V1 direction in FIG. 10 is forward rotation, and the opposite rotational drive direction is reverse rotation. 2 to 6 show a mirror-down state in which the movable mirror 15 is in the down position. The slider 44 is in a mirror-down holding position that holds the movable mirror 15 in the down position. More specifically, the first slider 45 has a biasing force applied to the first mirror up spring 51 and the second mirror up spring 52 by the cam follower 45j being pressed by the down holding surface C1 of the end cam 43c formed on the end cam gear 43. It is located below against. The second slider 46 is also positioned downward along with the first slider 45, and the movable mirror 15 is held at the down position by pressing the mirror sheet boss 16a downward by the mirror pressing portion 46c. The urging force of the slider coupling spring 53 is set to a strength that allows the second slider 46 to move away from the first slider 45 and not move upward alone and maintain the pressing of the mirror sheet boss 16a by the mirror pressing portion 46c. .

  As shown in FIG. 6, in the mirror-down state, there is an enlarged clearance M2 larger than the aforementioned minimum clearance M1 between the lower wall portion 45b of the first slider 45 and the second slider 46 and the mirror sheet boss 16a. The pressing part 45g is in a state of being spaced downward from the mirror sheet boss 16a. That is, when the movable mirror 15 is in the down position, the second slider 46 is restricted from further downward movement by the contact relationship between the mirror pressing portion 46c and the mirror sheet boss 16a, whereas the first slider 45 is restricted. The cam follower 45j is pressed against the down holding surface C1 of the end cam 43c, so that the second slider 46 is slightly moved (overcharged) by a small amount downward. Thus, by holding the first slider 45 in the overcharge position and providing the enlarged clearance M2 between the mirror sheet boss 16a, the down position of the movable mirror 15 due to the contact between the mirror sheet boss 16a and the down positioning protrusion 25 is provided. Thus, the first slider 45 does not affect the setting, and the movable mirror 15 can be positioned with high accuracy. In particular, at the down position of the movable mirror 15, it is necessary to precisely set the mirror position for distance measurement and photometry, and a margin for the position adjustment by the down positioning projection 25 is also required. It is effective to provide error absorption by providing

  When the user of the camera 10 lifts the movable mirror 15 in the up position direction with a finger or the like in the mirror down state, the mirror sheet boss 16a presses the mirror pressing portion 46c of the second slider 46 upward, and the slider connecting spring The second slider 46 is pushed upward while charging 53. At this time, the first slider 45 does not move upward, and the differential of the second slider 46 with respect to the first slider 45 is absorbed by the slider coupling spring 53, so that an excessive load is not applied to the mirror driving mechanism 40 and damage is caused. Can be prevented. When the lifting of the movable mirror 15 is released, the second slider 46 returns downward while releasing the charge of the slider coupling spring 53, and the movable mirror 15 also returns to the down position.

  When the down holding surface C1 of the end cam 43c of the end cam gear 43 faces the cam follower 45j of the first slider 45 in the mirror down state, the contact between the inner peripheral terminal 50a and the outer peripheral terminal 50b of the brush 50 with respect to the code plate 54 The portion is located in the down area U1 of FIG. In the down area U1, the mirror down switch is turned on when the inner peripheral terminal 50a of the brush 50 contacts the ground contact 54a and the outer peripheral terminal 50b contacts the mirror down contact 54b (see FIG. 11).

  When an operation signal accompanying mirror up such as shutter release or live view is input in the mirror down state, the control circuit 55 drives the mirror drive motor 41 to rotate forward (T1 in FIG. 11) and rotates the end cam gear 43. (Rotation in the V1 direction in FIG. 10). The down holding surface C1 has a predetermined width in the rotation direction of the end face cam gear 43, and while the down holding surface C1 is in contact with the cam follower 45j (the contact position of the brush 50 with respect to the code plate 54 is the down region in FIG. While in U1), the mirror drive motor 41 is driven forward at a constant speed (power).

  When the contact position of the outer peripheral side terminal 50b of the brush 50 with respect to the code plate 54 exceeds the edge E2 and enters the up transition region U2 by the rotation of the end face cam gear 43, the outer peripheral side terminal 50b moves away from the mirror down contact 54b and the mirror down switch Is turned off (T2 in FIG. 11). When the mirror down switch is turned off, the control circuit 55 decelerates and drives the mirror drive motor 41 to rotate forward (T3 in FIG. 11). As can be seen from FIG. 11, at this stage, the down-holding surface C1 of the end cam 43c is retracted from the position facing the cam follower 45j, and the up cam surface C2 faces the cam follower 45j. Then, the slider 44 whose upward movement restriction is released is moved upward from the mirror-down holding position by the urging force of the first mirror up spring 51 and the second mirror up spring 52. The mirror pressing portion 45g provided on the first slider 45 of the slider 44 moving upward pushes the mirror sheet boss 16a upward, and the movable mirror 15 rotates toward the up position. When the slider 44 moves upward, the overcharge of the first slider 45 with respect to the second slider 46 is released, and the clearance on the slider 44 side with respect to the mirror sheet boss 16a changes from the above-described enlarged clearance M2 to the minimum clearance M1. Since the minimum clearance M1 is ensured, a frictional resistance caused by sandwiching the mirror sheet boss 16a between the first slider 45 and the second slider 46 does not occur, and a smooth mirror-up operation can be performed. In addition, the durability of the drive mechanism of the movable mirror 15 is improved.

  From the mirror down state in which the cam follower 45j is pushed down by the end face cam 43c against the urging force of the first mirror up spring 51 and the second mirror up spring 52, the first mirror up spring 51 and the second mirror up spring 52 are attached. When shifting to the mirror-up operation that allows the cam follower 45j to move upward according to the force, the load on the end cam 43c changes. In particular, the cam follower 45j that receives the urging force of the first mirror up spring 51 and the second mirror up spring 52 tries to push up the cam surface C2 for the up, so that the end cam gear 43 is indicated by an arrow F1 in FIG. The torque (component force) in the rotation assist direction shown works. However, the mirror drive motor 41 is decelerated and driven to rotate forward during the mirror up operation (T3 in FIG. 11), thereby suppressing the acceleration of the end face cam gear 43 due to the assist torque, and the slider 44 and the movable mirror 15 according to the assumed cam curve. Can be operated.

  When the end cam gear 43 rotates while controlling the position of the slider 44 by the up cam surface C2, and the outer peripheral side terminal 50b of the brush 50 advances in the up transition region U2 and contacts the front contact 54e, the mirror up switch is turned on for a short time. Turns on (T4 in FIG. 11). Upon receiving this signal input, the control circuit 55 stops the forward drive (decelerated forward drive) of the mirror drive motor 41 (T5 in FIG. 11). At this time, both terminals of the mirror drive motor 41 are short-circuited to apply a short brake. Thereby, the end face cam gear 43 is decelerated while rotating by inertia. As can be seen from FIG. 11, at the stage where the forward rotation of the mirror drive motor 41 is stopped, the cam follower 45j is in contact with the gently sloping connection surface CM2 of the up cam surface C2, and the up allowable surface C3 continues. It is possible to smoothly shift the contact of the cam follower 45j with the cam follower 45j.

  When the end cam gear 43 continues to rotate by inertia after the mirror drive motor 41 stops rotating forward (T5 in FIG. 11), the outer peripheral terminal 50b passes through the front contact 54e and the mirror up switch is turned off (FIG. 11). T6). When the end cam gear 43 further rotates and the contact position of the outer peripheral terminal 50b of the brush 50 with respect to the code plate 54 exceeds the edge E3 and enters the up region U3, the mirror up switch is turned on again (T7 in FIG. 11). In response to this, the control circuit 55 applies a reverse brake that reversely rotates the mirror drive motor 41 for a short time (T8 in FIG. 11), and then stops the mirror drive motor 41 (T9 in FIG. 11). In this state, the end cam gear 43 is held at a position where the up-allowable surface C3 faces the cam follower 45j. When the cam follower 45j contacts the up allowable surface C3, the slider 44 is in the mirror up allowable position shown in FIG. 7, and the movable mirror 15 pushed up by the mirror pressing portion 45g of the slider 44 reaches the up position. In this mirror-up state, the above-described minimum clearance M1 exists between the mirror pressing portion 46c and the mirror sheet boss 16a, and the slider 44 does not affect the movable mirror 15 in the up position. In the mirror up state, the shutter 20 can be operated to perform exposure and live view.

  In the mirror up operation described above, when the contact position of the cam follower 45j changes from the down holding surface C1 of the end cam 43c to the up cam surface C2, the mirror driving motor 41 is decelerated and driven in the forward direction to drive the end cam gear. 43 (T3 in FIG. 11), and when the contact position of the cam follower 45j changes from the up cam surface C2 to the up allowable surface C3, the short brake (T5 in FIG. 11) of the mirror drive motor 41 The end cam gear 43 is stopped by the reverse brake (T8 in FIG. 11). In contrast to this, when the mirror drive motor 41 is not driven in the normal forward direction, the end cam gear 43 rotates faster than expected by the assist torque (F1 in FIG. 11) from the cam follower 45j when the mirror is raised, and the slider is moved when the mirror is raised. There is a possibility that the impact acting on 44 and the movable mirror 15 will increase. Although it is possible to select the timing of applying the short brake earlier to suppress the acceleration of the end face cam gear 43, the rotation of the end face cam gear 43 becomes too slow and affects the operation performance (the shooting frame speed) of the movable mirror 15. End up. On the other hand, by causing the mirror drive operation to be performed by the normal rotation drive of the mirror drive motor 41 that has been decelerated, the rotation of the end cam gear 43 does not become too slow or too fast, and the mirror up with high accuracy at an optimum speed Operation can be realized.

  The drive speed switching of the mirror drive motor 41 from T1 to T3 in FIG. 11 is performed by a method of changing a duty ratio of a pulse waveform in PWM (Pulse Width Modulation) control or a method of changing a motor drive voltage. It can be carried out. The duty ratio in the PWM control of the mirror drive motor 41 can be changed by changing the time width between energization and non-energization in the cycle. Alternatively, the terminals of the mirror drive motor 41 can be temporarily short-circuited in a cycle to be in the off state similar to the non-energization, and the duty ratio can be changed by setting the short-circuit time width. The difference in the drive speed of the mirror drive motor 41 at T1 and T3 in FIG. 11 depends on the output of the mirror drive motor 41, the magnitude of the load fluctuation acting on the end face cam gear 43, etc. Taking PWM control as an example, the mirror drive motor 41 can be appropriately decelerated by setting the duty ratio to be smaller than 50% when the drive speed is reduced at T3. For example, when the duty ratio is set according to the duration of energization and non-energization, the length of the non-energization time with respect to the energization time exceeds 1 time (the non-energization time is longer than the energization time in each cycle). It is good to do so.

  Subsequently, in response to the transition signal from the mirror up state to the mirror down state, the control circuit 55 causes the mirror drive motor 41 to rotate normally (T10 in FIG. 11), and the end cam gear 43 is rotated. The rotation direction of the end face cam gear 43 at this time is a direction in which the facing area of the end face cam 43c to the cam follower 45j is changed from the up allowable face C3 to the down cam face C4. When the contact position of the outer peripheral terminal 50b of the brush 50 with respect to the code plate 54 exceeds the edge E4 and enters the down transition region U4, the outer peripheral terminal 50b moves away from the mirror up contact 54c and the mirror down switch is turned off (FIG. 11). T11).

  The down cam surface C4 is an inclined surface that increases the amount of downward projection as it moves away from the up allowable surface C3 and approaches the down holding surface C1, so that the mirror drive is performed with the down cam surface C4 facing the cam follower 45j. When the end cam gear 43 is rotated by the forward rotation of the motor 41, the down cam surface C4 gradually presses the cam follower 45j downward, and the slider is resisted against the urging force of the first mirror up spring 51 and the second mirror up spring 52. 44 is moved downward from the mirror up allowable position. By the downward movement of the slider 44, the mirror pressing portion 46c of the second slider 46 presses the mirror sheet boss 16a, and the movable mirror 15 is rotated from the up position to the down position.

  In the timing chart of FIG. 11, the operation of the mirror drive motor 41 after the mirror down operation is omitted, but the outer peripheral terminal 50b of the brush 50 advances in the down transition region U4 by the rotation of the end face cam gear 43, and the front contact 54d. When touched, the mirror down switch is turned on for a short time. Upon receiving this signal input, the control circuit 55 stops the forward rotation of the mirror drive motor 41 (short-circuits between the motor terminals and applies a short brake). The end face cam gear 43 continues to rotate due to inertia, the outer peripheral side terminal 50b passes through the front contact 54d, the mirror down switch is turned off, and the contact position of the outer peripheral side terminal 50b of the brush 50 with respect to the code plate 54 subsequently follows the edge E1. When it goes beyond the down range U1, the mirror down switch is turned on again. In response to this, the control circuit 55 reverses the mirror drive motor 41 for a short time and then stops. In this state, the down holding surface C1 contacts the cam follower 45j, the slider 44 reaches the mirror down holding position, and the movable mirror 15 is held in the down position.

  Contrary to the mirror up, when the mirror is down, the cam surface C4 for down presses the cam follower 45j against the load (indicated by the arrow F2 in FIG. 11) opposite to the rotation assist direction of the end face cam gear 43. Therefore, the torque in the rotation assist direction does not act on the end face cam gear 43 from the slider 44. Accordingly, in the mirror down operation, the control circuit 55 causes the mirror drive motor 41 to rotate forward (T10 in FIG. 11) at the normal speed without performing the deceleration control as in T3 in FIG. In other words, the control circuit 55 performs control so that the forward drive speed of the mirror drive motor 41 during the mirror up operation is slower than the forward drive speed of the mirror drive motor 41 during the mirror down operation. Yes.

As is clear from the above description, the end cam gear 41 is changed by changing the speed of the forward drive of the mirror drive motor 41 in accordance with the use situation of the end cam 43c of the end cam gear 43 (rotational position of the end cam gear 43). 43 rotation speed optimization is realized. In particular, when the assist torque is applied to the end cam gear 43 from the cam follower 45j compared to when the end cam 43c of the end cam gear 43 presses the cam follower 45j against the load, the mirror drive motor 41 is decelerated and rotated forward. By driving, the end face cam gear 43 can be rotationally driven at an appropriate speed without accelerating the end face cam gear 43 by the assist torque and without excessive deceleration of the end face cam gear 43 by the brake of the motor. Further, the rotational speed of the end face cam gear 43 is detected by detecting a change in the rotational position of the end face cam gear 43 by the brush 50 and the code plate 54 and changing the speed when the mirror drive motor 41 is driven and stopping the drive of the mirror drive motor 41. Can be controlled with higher accuracy and reliability.

  The present invention is not limited to the illustrated embodiment. For example, the illustrated embodiment is applied to a mirror driving mechanism of a single-lens reflex camera, but any other driving mechanism may be used as long as it has a basic structure of transmitting the driving force of a motor via a rotating cam member. Applicable. In the case of a single-lens reflex camera, there is known a shutter charge mechanism provided with a rotating cam member in addition to a mirror drive mechanism (for example, Japanese Patent Application Laid-Open No. 2010-266618), and the present invention can be applied to such a shutter charge mechanism. it can. Of course, you may apply this invention to the cam drive mechanism of apparatuses other than a single-lens reflex camera.

  In the illustrated embodiment, the end cam gear 43 is used as the rotating cam member. However, instead of such an end cam member, a peripheral cam member having a peripheral cam surrounding the rotating shaft can be used. As an example, in Japanese Patent Application Laid-Open No. 2010-266618 described above, a peripheral cam member is used for a mirror driving mechanism and a shutter charge mechanism of a single-lens reflex camera, and the present invention can be applied to drive control of the peripheral cam member. is there.

  In addition, the mirror drive motor 41 in the illustrated embodiment is a motor that can perform forward rotation and reverse rotation, but the present invention can also be applied using a motor that can be rotationally driven only in one direction. In this case, it is possible to cope with the control in which the reverse brake indicated by T8 is omitted in the motor drive sequence of FIG.

DESCRIPTION OF SYMBOLS 10 Camera 11 Camera main body 12 Lens barrel 12a Shooting lens 13 Lens mount 14 Mirror box 15 Movable mirror (quick return mirror)
16 Main mirror holding frame 17 Main mirror 18 Sub mirror holding frame 19 Sub mirror 20 Focal plane shutter 21 Image sensor 22 Penta prism 23 Eyepiece lens 25 Down positioning protrusion 26 Mirror up buffer material 27 Metering unit 28 Distance measuring unit 29 LCD monitor 40 Mirror drive mechanism 41 mirror drive motor 41a rotation output shaft 41b pinion 42 reduction gear train 43 end face cam gear (rotating cam member)
43a Gear part 43b Cylindrical cam part 43c End face cam 44 Slider (driven member)
45 First slider 45a Side plate portion 45b Lower wall portion 45c Upper wall portion 45d Connection wall portion 45e 45f Guide hole 45g Mirror pressing portion 45h Spring hook arm 45i Rear wall portion 45j Cam follower 46 Second slider 46a Guide hole 46b Guide projection 46c Mirror pressure Portion 47 First guide shaft 48 Second guide shaft 50 Brush 50a Inner peripheral terminal 50b Outer peripheral terminal 51 First mirror up spring (biasing means)
52 Second mirror up spring (biasing means)
53 Slider connection spring 54 Code plate 54a Ground contact 54b Mirror down contact 54c Mirror up contact 54d 54e Front contact 55 Control circuit (motor control means)
72 Mirror Drive Gear Block Case 72a Bottom Wall 72b Fixed Shaft 73 Mirror Drive Gear Block Cover (Support Member)
73a Upper wall part C1 Down holding surface C2 Up cam surface (relief cam area)
C3 Up permissible surface C4 Down cam surface (Pressing cam area)
E1 E2 Mirror down contact edge E3 E4 Mirror up contact edge F1 F2 Torque applied from cam follower to end cam gear U1 Down region U2 Up transition region U3 Up region U4 Down transition region

Claims (8)

motor;
A driven member having a cam follower;
A rotating cam member that is rotated by a driving force of the motor; and an inclination direction that is formed on the rotating cam member and presses the cam follower against a load by rotation of the rotating cam member by rotation driving of the motor in one direction. A cam surface including a pressing cam area and a relief cam area in an inclination direction opposite to the pressing cam area;
In a control device for controlling a cam drive mechanism having
The rotating cam member is rotated by the one-way rotational drive of the motor, and the pressing cam region and the cam follower face each other when the rotating cam member is at a rotational position where the relief cam region and the cam follower face each other. Motor control means for changing the rotational speed of the motor when the rotating cam member is in a rotational direction position to be
A support member that is not rotated by the motor and a code plate provided on one of the rotating cam members;
A brush provided on the other of the support member and the rotating cam member and having a terminal that contacts a contact on the code plate;
Have
The motor control means receives a signal representing a change in electrical connection between the brush terminal and the code plate contact due to the rotation of the rotary cam member, changes the rotational speed when the motor is driven, and the motor. To stop driving ,
When the rotary cam member is at a rotational position where the relief cam area and the cam follower face each other, and the rotational cam member is located at a rotational position where the pressing cam area and the cam follower face each other controller of the cam drive mechanism characterized by Rukoto to perform the rotation driving of the deceleration to the motor than. 2. A control device for a cam drive mechanism according to claim 1, wherein the motor control means changes the rotation speed of the motor by changing a duty ratio of a drive pulse waveform of the motor. 3. The control device for a cam drive mechanism according to claim 2, wherein the duty ratio is less than 50% when the rotary cam member is in a rotational direction position where the relief cam region and the cam follower face each other. . The control apparatus according to claim 2 or 3, wherein the cam drive mechanism, the motor control means, the control device of the cam drive mechanism for changing the duty ratio by varying the time width of the energization and non-energization of the motor in the period . The control apparatus according to claim 2 or 3, wherein the cam drive mechanism, the motor control means, the control device of the cam drive mechanism for changing the duty ratio by setting the time width for short-circuiting between the terminals of the motor in the period. 2. A control device for a cam drive mechanism according to claim 1, wherein the motor control means changes the rotational speed of the motor by changing a drive voltage of the motor. The control device for a cam drive mechanism according to any one of claims 1 to 6 ,
Biasing means for exerting a biasing force on the driven member to press the cam follower against the cam surface;
When the pressing cam area of the cam surface presses the cam follower, the load with respect to the rotation of the rotating cam member acts by the biasing force,
A control device for a cam drive mechanism in which an assist torque in the direction of rotation of the rotating cam member acts by the biasing force when the cam follower faces the relief cam region of the cam surface. motor;
A driven member having a cam follower;
A rotating cam member rotated by the driving force of the motor;
A tilting cam region formed on the rotating cam member and configured to press the cam follower against a load by rotation of the rotating cam member by rotation of the motor in one direction, and an inclination opposite to the pressing cam region Cam surface including a directional relief cam area;
A support member that is not rotated by the motor and a code plate provided on one of the rotating cam members;
A brush provided on the other of the support member and the rotating cam member and having a terminal that contacts a contact on the code plate;
In a control method for controlling a cam drive mechanism having
When the rotary cam member is in a rotational direction position where the pressing cam region and the cam follower face each other, the motor is driven to rotate in the one direction at a predetermined speed,
When the rotary cam member is in a rotational direction position where the escape cam region and the cam follower face each other, the motor is driven to rotate in the one direction at a speed different from the predetermined speed,
In response to a signal representing a change in electrical connection between the brush terminal and the code plate contact point due to the rotation of the rotating cam member, the motor is driven to rotate at the predetermined speed and at a speed different from the predetermined speed. and switching of the rotary drive, and a drive stop of the motor have rows,
When the rotating cam member is at a rotational position where the relief cam area and the cam follower face each other, the predetermined speed when the rotating cam member is located at a rotational position where the pressing cam area and the cam follower face each other. And a control method for a cam drive mechanism, wherein the motor is driven to rotate at a reduced speed .

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