JP2001174688A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of erroneous count of a pulse due to disturbance such as a noise and chattering in the case of executing lens control in which a rough pitch pulse and a fine pitch pulse are used in a step-zoom system. SOLUTION: In a camera having a means to generate a reference pulse signal by one pulse for respective plural zoom positions in accordance with the driving of a lens barrel, the means to generate a control pulse signal by plural pulses for each zoom position in accordance with the driving of the lens barrel and a controlling means executing driving until the number of the control pulse signal generated after the rise time or the fall time of the reference pulse signal reaches a focusing target value when the lens barrel is driven in a stand-by state respectively provided for the plural zoom positions, the absolute driving state of the lens barrel in the stand-by state is detected by the controlling means based on a successive signal successively changing in accordance with the driving of the lens barrel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lens drive control in a so-called step zoom camera.

[0002]

2. Description of the Related Art In a zoom lens used for a camera,
In general, each lens group performs a zooming operation, and at the time of focusing, the focus group independently performs a focusing operation. The motorized zoom lens has two types of driving sources, one for zooming and one for focusing.

On the other hand, in recent years, Japanese Patent Application Laid-Open No. 61-25923 has been disclosed.
A configuration in which a focusing operation is performed during a zooming operation by using the method proposed in Japanese Patent Application Publication No. 7-1995 is also in practical use. In this configuration, since the simplification of the mechanism and the simplification of the control system can be realized, the advantages of cost reduction and compactness can be exploited (the above method is referred to as a step zoom method).

In this step zoom method, since a zooming operation also serves as a focusing operation, a high-precision one that satisfies the focusing accuracy is required for its position control. FIG. 5 conceptually shows the step zoom method. 101 is a first lens group, 102
Is a second lens group, and respective trajectories 103 and 104 are
It is usually at the infinity focus position during zooming. On the other hand, in the step zoom method, the second lens group 102 moves on a locus 105, and the locus 105 moves to a next zoom position and a focusing area where the focal position is continuously changed from infinity to a close position. It consists of a variable magnification area. In FIG. 5, there are a total of five zoom positions from f = 35 to 90 mm.

The reference pulse is output for one cycle for each zoom position. As a method of outputting the reference pulse, for example, a method of providing a means for generating a pulse intermittently in conjunction with a gear in the middle of a drive transmission gear system for performing a zoom drive, a method of providing an optical axis direction or a rotation direction of a lens barrel, or the like. There is a method of generating a signal directly from movement.

The required pitch of the Focus pulse is determined by the focusing accuracy, but f = 3 shown in FIG.
In the case of the first-group focusing method in a 5-group-constituting optical system of 5 to 90 mm, an accuracy of usually several μm to several tens μm is required. That is, since it requires several hundred times the fineness of the reference pulse, it is difficult to obtain a signal directly from the lens barrel. Therefore, the first stage of the zoom drive mechanism, that is, the gear near the motor or the motor direct, focuses on the focal point.
Generally, an s pulse is generated.

The focusing operation of the above configuration will be described. For example, when the photographing state of f = 50 mm is set in the zooming operation, the lens barrel and the photographing lens group
WI from reference pulse switching (falling) point 106
It stops at a predetermined position 107 on the DE side as a standby position. When the camera starts the photographing operation by the photographing operation of the photographer, the distance and the luminance of the subject are measured, and the focusing drive is started. When the lens barrel starts operating for focusing drive, the TELE
Each lens group starts moving toward the side.

When the signal at the reference pulse switching point 106 is detected, the number of Focus pulses is counted based on the detection time, and when the number of Focus pulses reaches the number of pulses calculated from the result of the distance measurement, the lens is used. To stop. Thereafter, exposure based on the result of the photometry is performed.
When the exposure is completed, the lens barrel is reset to the standby position 107, the film is wound up by one frame, and the photographing operation ends.

As described above, in the step zoom method,
Fine pitch signal (F
The lens position control is performed using two types of signals, that is, a signal having a coarse pitch (reference pulse) and a signal having a coarse pitch (reference pulse) serving as a control base point.

[0010]

However, since the signals used in the conventional step zoom method are signals generated intermittently at the same output level, the signals are used to determine the absolute driving state of the lens barrel. (Absolute position of lens)
Can not know. In other words, the camera cannot know from these signals which photographing magnification (focal length) is currently set for the lens barrel.

For this reason, there is usually provided a means for generating another signal of a predetermined reset state of the lens barrel, a reference pulse is counted based on this signal, and this count value is used as drive state information. I have.

For example, most recent zoom cameras are designed so that the lens barrel is retracted compactly with respect to the camera body in a non-photographing state for the sake of compactness. A switch for detecting the state of the retracted end is provided. In addition to detecting the retracted state and counting the reference pulse based on the signal from the retracted end switch during the standby operation started by turning on the main switch of the camera, The drive state is detected.

As described above, conventionally, since a true absolute driving state is not detected and an estimated driving state is used, there are the following drawbacks.

Due to erroneous counting of pulses due to disturbances such as noise and chattering, a photographing operation may be performed based on driving state information that is different from the actual one. In this case, photographing is performed without focusing and exposure accuracy being incorrect. And this erroneous detection is detected by the ON-OF of the main switch.
This will continue until the lens barrel is reset by F.

In addition to the above-described disturbance, the same erroneous detection state as described above can also be obtained when the photographer inadvertently moves the lens barrel (for example, when the lens barrel is hit while walking). Had become.

Further, when a reset operation of the camera is required, it is necessary to always operate the lens barrel reset to a reset state such as a retracted end, and there is a disadvantage that the reset operation is complicated. For example, there is a disadvantage that the lens barrel must always be retracted when changing the film, which is inconvenient.

Further, as a problem in a case where each zoom position is erroneously detected, the camera side has the MIDDL even though the photographing lens is already in the TELE position.
If the photographer further operates the camera to the TELE side when the camera is erroneously detected as being at the E position, the lens barrel becomes TE
It stuck at the LE end and could not move further to the TELE side. The camera determines that this is a failure and performs error processing.This is not a failure, but unnecessarily gives the photographer distrust and discomfort. There is also a disadvantage that an unnecessary load is applied to the mechanism.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the erroneous detection of the driving state of the lens barrel and improve the usability of a step zoom type camera.

[0019]

In order to achieve the above object, according to the present invention, a plurality of zoom positions are set stepwise by moving two lens groups, and both zoom positions are set within the set zoom positions. A lens barrel that performs focusing by changing the relative positions of the lens groups, a unit that generates a reference pulse signal for each pulse at each zoom position in accordance with the driving of the lens barrel, and a unit that generates a reference pulse signal in accordance with the driving of the lens barrel. A means for generating a control pulse signal for each of a plurality of pulses for the zoom position, and the lens barrel is driven to one of standby states provided for each of the plurality of zoom positions within the movable range of the lens barrel. rear,
A camera having control means for driving until the number of control pulse signals generated from the rise or fall of the reference pulse signal reaches the focusing target value from this standby state, the camera is driven within the movable range of the lens barrel. There is also provided means for generating a continuous signal that changes continuously with the driving of the lens barrel, and the control means controls the standby state based on the continuous signal when the lens barrel is driven to each standby state. The absolute driving state in the movable range is detected.

That is, prior to the focusing operation in the zoom position, it is confirmed that the lens barrel is in the standby state corresponding to the zoom position by detecting an absolute driving state by a continuous signal (further, a control pulse signal). Reset the occurrence count of
With this configuration, it is possible to prevent the lens barrel from malfunctioning due to erroneous pulse counting and erroneous detection as in the related art.

When the lens barrel operates after detecting the absolute driving state in the standby state (for example, when a photographing operation is performed), the lens barrel returns to the standby state corresponding to the result of the above detection. By doing so, it is possible to suppress the occurrence of problems such as erroneous counting of pulses, even if shooting is repeated many times.

Further, since it is possible to detect the absolute driving state in a state where the lens barrel is on standby by a continuous signal, it is possible to hold the lens barrel in the standby state even at the time of film exchange or the like. It becomes possible. Therefore,
Usability is improved as compared with a conventional camera in which a lens barrel is reset and driven to a stored state or the like when changing a film.

Further, if the lens barrel is driven to the end of the movable range (for example, the storage state with respect to the camera body) based on the continuous signal, it is detected that the lens barrel is driven to the end of the movable range as in the prior art. It is not necessary to separately provide a switch or the like for performing the operation.

[0024]

FIG. 1 mainly shows a lens barrel of a camera according to an embodiment of the present invention and a drive configuration thereof.

In this figure, reference numeral 1 denotes a lens barrel drive motor driven and controlled by a control circuit 15, 2 denotes a pinion gear fixed to an output shaft of the motor 1, and 3 denotes a Focus pulse held so as to rotate coaxially with the motor 1. Board, 4 is Focu
This is a photo interrupter that optically detects a slit of the s pulse plate 3 and outputs a pulse corresponding to the rotation of the motor.

Reference numerals 5, 6, and 9 denote gear trains for reducing and transmitting the power of the pinion gear 2, reference numeral 7 denotes a reference pulse plate held so as to rotate coaxially with the gear 6, and reference numeral 8 optically detects a slit of the reference pulse plate 7. And outputs a pulse corresponding to the rotation of the gear 6.

Reference numeral 10 denotes a lens barrel, which includes a fixed barrel 19,
A cam cylinder 17 rotatable around the optical axis by a driving force from the gear 9 in the fixed cylinder 19, and first-group holders 16 and 2 respectively engaging with cam grooves formed in the cam cylinder 17
And a group holder 18.

The fixed barrel 19 and the cam barrel 17 are helicoidally connected, and the cam barrel 17 advances and retreats in the optical axis direction with respect to the fixed barrel 19 by rotating. The first-group holder 16 and the second-group holder 18 hold the first-group lens 11 and the second-group lens 12, respectively. Move in the axial direction. The control circuit 15 controls all control operations of the camera.

In the above configuration, the focus pulse plate 3 is directly driven by the motor 11, so that the photo interrupter 4 generates a focus pulse (control pulse signal), which is a signal with a fine pitch, and inputs the signal to the control circuit 15.

On the other hand, since the reference pulse plate 7 is driven by the rotation of the motor decelerated by the gears 5 and 6, the photo interrupter 8 generates a reference pulse (reference pulse position), which is a signal of a coarse pitch, and performs control. Input to the circuit 15.

Numeral 14 denotes an absolute position detection board mounted on the inner surface of the fixed cylinder 19. As shown in FIG. 2, a conduction pattern 20 and a resistance pattern 21 arranged in parallel are formed on the absolute position detection board 14, and the contact piece 13 slides on these patterns 20 and 21. Thus, a voltage changing circuit using the variable resistance circuit shown in FIG. 3 is configured.

That is, an absolute position signal (continuous signal) which is a voltage value corresponding to the position of the contact piece 13 which moves together with the second group holder 18, that is, the position of the photographing lens (the driving state of the lens barrel) is supplied to the terminals b and c. Can be taken out from between. Then, the voltage between the terminals b and c is input to the control circuit 15.

Next, the drive control of the lens barrel 10 by the control circuit 15 using the above-mentioned Focus pulse, reference pulse and absolute position signal will be described with reference to FIG.

In FIG. 4, reference numerals 32 and 33 denote a first lens unit.
The movement locus when the first and second lens groups 12 are zoomed from f = 35 mm to f = 90 mm while maintaining the relationship of the infinite focal position is shown.

Numeral 34 denotes a two-group lens 1 in a step zoom system when focusing is performed by extending one group.
2 is the movement locus. Although the locus 34 is shown in a simplified manner in FIG. 4, the actual locus 34 is set to be different for each zoom position.

In this embodiment, the first lens unit 11 is moved along the locus 3
2 and the second group lens 12 is moved along the locus 3
4 along with f = 35 mm (WI
DE), f = 50 mm (MIDDLE1), f = 70 m
m (MIDDLE2), f = 80 mm (MIDDLE2)
3) and five zoom positions of f = 90 mm (TELE) can be selectively set.

For example, when the photographing state is set to f = 50 mm in the zooming operation, first, the lenses 11 and 12 are moved beyond the reference pulse switching point (in the present embodiment, the falling point, but may be the rising point) 35. The position 36 on the WIDE side is stopped as a standby position. Then, at this time, the control circuit 15 detects the voltage Va obtained as the absolute position signal so that the lenses 11 and 12 can move the lenses 11 and 12 to the standby position 3 without error.
Confirm that it stopped at 6. Then, the Focus pulse counter is reset in response to the confirmation.

Here, such a standby position is similarly provided at each of the zoom positions, and the voltage V
By detecting a, it is possible to confirm whether the lenses 11 and 12 have stopped without error at the standby positions corresponding to the selected zoom positions.

Incidentally, as a method of moving the lenses 11 and 12 to the standby position, Foc is applied from the point of detection of the reference pulse.
As a method of driving until the number of us pulses reaches a predetermined number corresponding to the standby position, there is a method of driving by performing position detection based on a continuous signal. When the camera starts operating according to the photographing operation of the photographer, the distance and luminance of the subject are measured, and then the focusing drive is started.

At this time, based on the distance data, the number of Focus pulses (focusing target value) for driving the first lens group 11 from the time when the reference pulse switching point 35 to be detected later is detected is determined in the control circuit 15. Called from memory.

When the lenses 11 and 12 are moved from the standby position 35 to TE.
When the signal moves toward the LE side and the signal of the reference pulse switching point 35 is detected, the number of Focus pulses is counted from the detection. Then, when the count number reaches the Focus pulse number called from the memory first, stop control of the lenses 11 and 12 is performed.

Since there is actually an effect of the inertia of the motor 1 and the like, the brake control of the motor 1 is performed a little before, and the lenses 11 and 12 are stopped just when the count number reaches the Focus pulse number. To Thereafter, the control circuit 15 performs film exposure control based on the subject luminance data.

When the exposure control is completed, the control circuit 15
It is reset to the original standby position 36. Here, the absolute position signal is detected again, and it is confirmed whether or not the lenses 11 and 12 have returned to the standby positions 36. Finally, the control circuit 15 winds up the film by one frame and ends the photographing operation.

As described above, in the present embodiment, the lenses 11 and
Before performing the focusing operation in the zoom position 12, it is confirmed that the lenses 11 and 12 are located at the standby positions corresponding to the zoom position.
Since the count of the s pulse is reset, it is possible to prevent the lens from malfunctioning due to erroneous pulse count or erroneous detection as in the related art.

This also allows the lenses 11 and 12 to move
It is also possible to prevent a so-called thrust by driving the lenses 11 and 12 in the TELE direction by erroneously detecting that they are in the MIDDLE area despite being at the ELE end. In the present embodiment, after the focusing operation is completed and the photographing operation is completed, the lenses 11 and 12 can be accurately returned to the (original) standby position before the focusing operation. However, it is easy to prevent problems such as erroneous pulse counting and erroneous detection.

Further, since it is possible to hold the camera at the standby position even at the time of changing the film, it is possible to eliminate the inconvenience of the conventional camera which is moved to the retracted position each time.

On the other hand, when the main switch is turned off to move the lens barrel with respect to the camera body in the retracted state, the control circuit 15 sets the absolute position signal Va to a predetermined value (for example, 0). , Control. For this reason,
There is no need to provide a retractable end switch as in the prior art.

In this embodiment, a camera using a film has been described. However, the present invention can be applied to a so-called digital camera.

[0049]

As described above, according to the present invention,
Prior to the focusing operation at the zoom position, it is confirmed that the lens barrel is in the standby state corresponding to the zoom position by detecting the absolute driving state by a continuous signal (Furthermore, the count of the number of generated control pulse signals is checked. Resetting), it is possible to prevent the lens barrel from malfunctioning due to erroneous pulse counting and erroneous detection as in the related art.

When the lens barrel operates after detecting the absolute driving state in the standby state (for example, when a photographing operation is performed), the lens barrel returns to the standby state corresponding to the result of the above detection. By doing so, it is possible to suppress the occurrence of problems such as erroneous counting of pulses regardless of how many times shooting is repeated.

Further, since it is possible to detect the absolute driving state in a state where the lens barrel is on standby by a continuous signal, it is possible to hold the lens barrel in the standby state even when changing the film. it can. Therefore, usability can be improved as compared with a conventional camera in which the lens barrel is reset and driven to a stored state or the like at the time of film exchange or the like.

Further, if the lens barrel is driven to the end of the movable range (for example, the storage state with respect to the camera body) based on the continuous signal, it is detected that the lens barrel is driven to the end of the movable range as in the prior art. It is not necessary to separately provide a switch or the like for performing the operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an absolute position detection board in the camera.

FIG. 3 is a configuration diagram of a circuit for detecting an absolute position of a photographing lens of the camera.

FIG. 4 is a diagram showing a relationship between the photographing lens and a signal state.

FIG. 5 is a diagram showing a relationship between a conventional photographing lens and a signal state.

[Explanation of symbols]

 Reference Signs List 1 motor 3 Focus pulse plate 4, 8 photo interrupter 7 reference pulse plate 10 lens barrel 11 first lens group 12 second lens group 13 contact piece 14 absolute position detection board

Claims (6)

[Claims] A lens barrel that moves two lens groups to set a plurality of zoom positions in a stepwise manner and changes a relative position of both lens groups within the set zoom position to perform focusing; Means for generating a reference pulse signal by one pulse for each of the zoom positions in accordance with the driving of the lens barrel; means for generating a control pulse signal by a plurality of pulses in each of the zoom positions in accordance with the driving of the lens barrel After driving the lens barrel to one of standby states provided for each of the plurality of zoom positions within the movable range of the lens barrel, from this standby state,
A control means for driving until the number of control pulse signals generated from the rise or fall of the reference pulse signal reaches the focusing target value, wherein the lens barrel is moved within the movable range of the lens barrel. It also has a means for generating a continuous signal that changes continuously with the driving, the control means, when the lens barrel is driven to each of the standby states, based on the continuous signal, A camera for detecting an absolute driving state in the movable range in a standby state. 2. The camera according to claim 1, wherein the control unit controls the driving of the lens barrel within a zoom position after detecting the absolute driving state in the standby state. 3. When the lens barrel operates after detecting the absolute driving state in the standby state, the control unit returns the lens barrel to a standby state corresponding to the result of the detection. The camera according to claim 1 or 2, wherein: 4. The control unit according to claim 1, wherein the control unit resets the count of the number of generations of the control pulse signal in response to detecting the absolute drive state in the standby state. Camera. 5. The camera according to claim 1, wherein the control unit drives the lens barrel to a movable range end based on the continuous signal. 6. The camera according to claim 5, wherein the movable range end is in a state where the lens barrel is housed in a camera body.