JPS61251813A - Camera - Google Patents

Abstract

PURPOSE:To prevent a hand shake effectively by making the time required for focusing operation nearly constant and shortening the overall focusing time even when the time required to select a stepped cam is long. CONSTITUTION:The time when a guide pin 51 is pressed to a selected step after step selecting operation is varied reversely according to a result of range finding. For example, when the number of pulses from a printed board 22 is, for example, five or small, its selection time is Ta, but if the depression time at this time is Tb, the selection time corresponding to eight pulses is Ta' (>Ta), so the depression time is set to Tb' (<Tb) and let Ta+Tb Ta'+Tb', preventing the time required for focusing operation from being affected by the result of range finding. Thus, when the time required for selecting operation becomes long, the depression time is shortened to shorten the overall time required for focusing operation, thus preventing a hand shake.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a camera equipped with an automatic focus adjustment device, which shortens the operating time for moving a photographic lens to a focusing position based on a distance measurement result.

[Background technology]

As an automatic focus adjustment device, a stage cam having multiple stages corresponding to multiple focal positions is arranged, and a predetermined stage of the stage cam is selected according to the distance measurement result to the subject. It can be configured such that the photographing lens is moved from the reference position in the optical axis direction and pressed against it.

However, when the subject is close, the distance from the reference position to the focal position on the optical axis of the photographic lens is short, but when the subject is far away, the distance becomes long.

Therefore, depending on the distance to the subject, that is, the distance measurement result, the amount of movement of the photographic lens will differ, and the time for automatic focus adjustment will vary. There is a possibility that this may occur.

[Purpose of the invention]

The present invention has been made in view of the above points, and
The purpose is to provide a camera in which the required operating time for the photographing lens to focus remains approximately constant regardless of the distance measurement result, and the required time is shortened.

[Structure of the invention]

To this end, the present invention provides a step cam in which a plurality of stages are formed corresponding to a plurality of focus positions, a selection mechanism that selects the step of the step cam according to a distance measurement result, and a selection mechanism that selects the step of the step cam according to a distance measurement result. It is equipped with a pressing mechanism that presses the photographic lens against the selected step,
The longer the time required for the selection operation of the selection mechanism mentioned above, the shorter it is;
The pressing time of the pressing mechanism is set as long as it is short.

〔Example〕

Examples of the present invention will be described below. FIG. 1 shows an exploded perspective view of the mechanism of the automatic focus adjustment device, and this mechanism is incorporated into the lens barrel of the camera as a unit.

Reference numeral 10 denotes an electromagnetic unit fixed within the lens barrel, and inside it, in addition to a first movable coil member (not shown) that controls the exposure amount of the photographic lens 50, there is also a second movable coil member (not shown) in which a regulating pin 11 (to be described later) is implanted. A movable coil member 12 is provided so as to be rotatable about the optical axis.

A lens guide 20 is attached to the front surface of the optical axis of the electromagnetic unit 10, and is composed of a flange part 21 and a cylindrical part 26. A printed board 22 having a detection pattern for feedback and a stop pawl 24 biased clockwise by a tension spring 23 are pivotally mounted. This stop claw 24 is connected to the flange portion 21.
The rotation in the clockwise direction is restricted by the locking action of the regulating pin 11 that passes through the cylindrical portion 26. On the other hand, the cylindrical portion 26 has three linear grooves 27 on its circumferential surface arranged at equal angular intervals to align the optical axis. The guide pin 51 of the photographing lens 50 formed in the direction and slidably fitted on the inner circumference is in the straight groove 2.
7, thereby allowing the photographic lens 50 to move in the optical axis direction.

Reference numeral 40 denotes a lens driving member rotatably fitted to the outer periphery of the cylindrical portion 26 of the lens guide 20, and the cylindrical portion 41
The guide pin 51 of the photographic lens 50 is inserted into the three oblique cam grooves 42 provided in the cam groove 42, and cooperates with the straight groove 27 to regulate the position of the photographic lens 50 in the optical axis direction. .

Further, in this lens driving member 40, a pinion 61 that meshes with a gear portion 47 provided on the flange portion 46 is connected to a motor 60.
By being rotated by , it is possible to rotate clockwise from the illustrated position and reverse to return.

Reference numeral 30 denotes a lens positioning member that fits onto the cylindrical portion 41 of the lens driving member 40, and a step cam 31 consisting of a plurality of steps corresponding to a plurality of focusing positions is formed on the end surface of the lens.
By bringing the guide pin 51 of the photographing lens 50 into contact with one of the stages, the photographing lens 50 is set at a predetermined focusing position. Note that three stepped cams 31 are provided corresponding to the number of guide pins 51.

The lens positioning member 30 and the lens driving member 40 are configured such that the tip of the pressing spring 33 attached to the protrusion 32 of the lens positioning member 30 engages with a V-shaped notch 48 provided in the flange portion 46 of the lens driving member 40. By doing so, they are integrated and rotated simultaneously by the motor 60.

The other protrusion 34 of the lens positioning member 30 has a contact piece 3.
5 is attached, and by sliding the circuit pattern on the printed board 22 of the lens guide 20 according to the rotation of the lens driving member 40, a pulse signal corresponding to the amount of movement of the photographing lens 50 is sent out. Further, other portions are provided with pawl teeth 36 to engage with the stop pawl 24.

The lens driving member 40 and the lens positioning member 30 are held between the front surface of the flange portion 21 of the lens guide 20 and the back surface of the presser plate 70 attached to the flange portion 210 via the three pillars 71, and are rotated. It is free.

Now, when the distance measuring device detects the distance to the subject in conjunction with the operation of operating the camera release, the shooting lens 5
0 focusing operation is started. This operation is shown in Figures 2 and 3.
This will be explained with reference to the figures.

First, as shown in FIG. 2 (al), the step cam 31 of the lens positioning member 30 and the groove cam 42 of the lens drive member 40 are substantially parallel to each other, although they are curved with a slight spacing between them. At this time, the guide pin 51 of the photographic lens 50
The mark is located on the lower end side of the thin cam 42 in the figure, that is, on the tip side of the optical axis.

Next, when a positive current is applied to the second movable coil member 12, a clockwise moving torque is applied to the regulating pin 11, and the stop claw 24 is inadvertently moved to the claw 3 of the lens positioning member 30.
If it is engaged with 6, it is released. That is, first, the stop pawl 24 is unlocked.

Next, with a slight delay from the operation of the regulating pin 11, the motor 60 starts to rotate normally, and the lens driving member 40 and the lens positioning member 30 are simultaneously rotated clockwise (in the six directions of arrows in FIG. 2).

Along with this operation, the photographing lens 50 recedes linearly,
At the same time, the contact piece 35 starts sliding against the printed board 22, and a number of pulses corresponding to the amount of rotation of the photographic lens 50, that is, the amount of movement in the optical axis direction, are sent out from the printed board 22.

Then, when the number of pulses matches the number of pulses set in advance in accordance with the distance measurement result, the normal rotation of the motor 60 is stopped.

Next, a little later than the stop of the motor 60, a negative current is applied to the second movable coil member 12, whereby the regulation pin 11 is rotated counterclockwise, and the stop pawl 24 is engaged with the pawl teeth 36. However, the rotation of the lens positioning member 30 is locked.

As described above, the guide pin 51 is guided to the front spaced from any selected stage of the stage cam 31 of the lens positioning member 30 (the stage corresponding to the distance measurement result). Figure 2 (b
The reference numeral 51a indicates the position of the guide pin 51. This completes the selection operation of selecting a specific stage corresponding to the distance measurement result of the stage cam 31.

Next, after a slight delay from the locking of the lens positioning member 30, the motor 60 again starts normal rotation, and the lens driving member 40 further rotates clockwise.

At this time, the pressing spring 33 attached to the lens positioning member 30 comes off from the notch 48 of the lens driving member 40, and the lens driving member 40 rotates independently.

Due to the normal rotation of the lens driving member 40 again, the photographing lens 5 which was held at a position separated from the stepped cam 31
The 0 guide pin 51 is pressed against the stage in front of it, as shown by reference numeral 51b in FIG. 2(b), and sets the photographing lens 50 at the optical axis position corresponding to the distance measurement result. Thereafter, when a predetermined period of time has elapsed, the motor 60 stops normal rotation.

In this way, the photographing lens 5o is focused on the subject, and then exposure is performed by the operation of the first movable coil member (not shown), and the shutter operation is completed.

When this shutter operation is completed, a positive current flows through the second movable coil member 12 again, the regulating pin 11 moves clockwise, the stop pawl 24 disengages from the pawl teeth 36, and the lock is released. .

Next, the motor 60 starts reverse rotation, and first rotates the lens drive member 40 counterclockwise to linearly advance the photographing lens 50, so that the notch 48 is aligned with the lens positioning member 30.
When it reaches the position where it engages with the pressing spring 33, it is integrated with the lens positioning member 3° and further rotates counterclockwise to return to its initial state, after which the motor 60 stops.

By the way, the distance that the guide pin 51 moves to the front of a predetermined stage of the stage cam 31 is a length that corresponds to the distance to the subject. For example, if the distance to the subject is long, it is necessary to send out many pulses. Therefore, the moving distance of the guide pin 51 becomes long.On the other hand, if the distance to the object is short, fewer pulses need to be sent out, so the moving distance of the guide pin 51 can be shortened.

Therefore, the time required to select a predetermined stage of the stage cam changes depending on the distance measurement result, and this cannot be avoided.

Therefore, in the present invention, the time period during which the guide pin 51 is pressed against the selected stage after the stage selection operation is changed in the opposite manner to the above, depending on the distance measurement result. For example, as shown in FIG. 3, when the number of pulses from the printed circuit board 22 is as small as five, the selection time is Ta.
However, if the pressing time at that time is Tb, as shown in Figure 4, if there are 8 pulses, the selection time will be Ta'(>Ta), so the pressing time will be Tb.
b'(<Tb), rTa +Tb=Ta'
+Tb'J so that the time required for the focusing operation is not affected by the distance measurement results.

In this way, when the time required for the selection operation is long, the pressing time is shortened, thereby reducing the overall time required for the focusing operation and preventing the occurrence of hand movements.

In the camera prototyped by the present inventor, the distance measurement results were divided into 13 stages, and the number of stages of the stage cam was set to 13. When the number of pulses obtained from the distance measurement results is in the range of 1 to 6, the pressing time of the guide pin 51 is set to 70 ms, and when the number of pulses obtained from the distance measurement is in the range of 7 to 13, the pressing time is set to 50 m5.
However, due to manufacturing and other reasons, there are only two types of pressing times, and it goes without saying that the pressing times can be set for each number of pulses.

In the above embodiment, the selection mechanism that selects the stage of the stage cam according to the distance measurement result and the pressing mechanism that presses the photographing lens against the selected stage of the stage cam are provided by the lens guide 20, the lens positioning member 30, The lens driving member 40, the guide pin 51 of the photographing lens 50, and the pressing spring 33 are commonly configured, and when a stage is selected, the lens positioning member 30 and the lens driving member 40 are integrally moved to move to the selected stage. During the pressing operation, the lens positioning member 30 is locked and only the lens driving member 40 is moved; however, the present invention is not limited to this, and the selection mechanism and the pressing mechanism may be configured as completely independent mechanisms. You can also do that.

〔Effect of the invention〕

From the above, according to the present invention, the time required for focusing operation is kept almost constant, and even when the time required for selecting a stage cam is long,
The overall focusing time can be shortened, and the occurrence of camera shake can be effectively prevented. Furthermore, as shown in Figure 2, when the distance between the stepped cam and the grooved cam in the optical axis direction is different between the near distance side and the far distance side, the lens pressing time is set to be shorter on the side with the smaller distance. Therefore, it is also effective in preventing overcurrent to the motor after pressing.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of the automatic focus adjustment device, Figure 2 (a)
, (b) are explanatory diagrams of operations of main parts, and FIGS. 3 and 4 are timing charts of focusing operations.

Claims (1)

[Claims] (1) In a camera equipped with an automatic focus adjustment device that moves a photographing lens to a focusing position according to a distance measurement result, a stepped cam having a plurality of stages corresponding to a plurality of focusing positions, and It is equipped with a selection mechanism that selects a stage of the cam according to the distance measurement result, and a pressing mechanism that presses the photographing lens against the selected stage of the stage cam, and the longer the time required for the selection operation of the selection mechanism, the shorter the time. ,
A camera characterized in that the pressing time of the pressing mechanism is set as long as it is short.