JPH06324247A - Controller for camera - Google Patents

Abstract

PURPOSE:To provide a controller by which the home position of a rear group lens is checked even at the time of performing zooming operation in a two-group system zoom device. CONSTITUTION:In a camera having the zoom device constituted of a front group lens driven by a DC motor 42 and the rear group lens driven by a stepping motor 44; the controller checks whether or not the rear group lens is properly arranged at the home position by the use of a home position sensor 36 by moving the rear group lens to the home position when a focal distance is the longest at the time of performing the zooming operation. When abnormality is detected by checking the home position, only a specified switch such as a main switch is allowed to function and the input of other switches is made invalid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a zoom device, and more particularly to a home position check of a rear lens group of the zoom device.

[0002]

2. Description of the Related Art In recent years, in cameras, particularly compact cameras, there has been a demand for miniaturization of the entire outer shape.
An important issue is how to downsize the lens barrel. And in a camera with a two-group zoom device,
In order to reduce the size of the lens barrel, a mechanism in which the front lens group and the rear lens group are driven by separate motors tends to be adopted instead of the mechanical cam. In this mechanism, a DC motor is used as a motor for driving the front lens group,
A stepping motor is generally used as a motor for driving the rear lens group.

As this two-group type zoom device, there is one having a structure as shown in FIG. The lens barrel 4 of the zoom device 2 includes a fixed barrel 6 that forms a part of the camera body, an intermediate barrel 8 that is housed in the fixed barrel 6 in a telescopic manner, and is further housed in the intermediate barrel 8 in a nested manner. And the movable cylinder 10 that has been moved.

A front lens group 22 is provided in the front end of the movable barrel 10.
Is fixed, and is driven forward and backward integrally with the movable barrel 10 by a DC motor (not shown).

The front lens group 22 is provided in the movable barrel 10.
A rear lens group 28 is disposed behind (on the camera body side) so as to be movable back and forth. The rear group lens 28 is driven back and forth by a stepping motor (not shown).

It should be noted that FIG. 1A shows the maximum telephoto state with the longest focal length, and FIG. 1B shows the widest angle state with the shortest focal length.

In such a zoom device 2, the position of the front lens group 22 can be constantly detected by a position sensor 24 composed of a sliding resistor or the like. on the other hand,
Regarding the position of the rear group lens 28, a position where the rear group lens 28 comes closest to the front group lens 22 is set as a reference position (in this specification, this position is referred to as “home position”),
It is determined from the total (cumulative number of pulses) of the pulse signals output to the stepping motor. Then, the fact that the rear lens group 28 is arranged at the home position is detected by using a home position sensor including a limit switch or a photoelectric sensor.

[0008]

In the conventional zoom device as described above, the home position for moving the rear group lens to the home position and confirming whether or not the rear group lens is properly arranged at the home position. The check is performed only when the lens barrel is driven from the retracted position in the camera body to the widest angle state shown in FIG. 1 (b). For this reason, conventionally, the position of the rear lens group during the zoom operation can be obtained only from the cumulative pulse number stored in the RAM.

Therefore, when an abnormality occurs in the driving of the stepping motor due to a decrease in the driving voltage or the like, the position of the rear lens group obtained from the cumulative number of pulses is different from the actual position. There is. This misalignment,
If so-called step-out occurs, the rear group lens cannot be accurately arranged at the focusing position during exposure, and problems such as out of focus occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a camera control device capable of checking the home position of the rear lens group even during zooming.

Another object of the present invention is to limit the operable switches because proper photographing cannot be performed when an abnormality is found in the driving of the rear lens group by the home position check during zooming. Especially.

[0012]

In order to achieve the above object, a control device according to the present invention is a zoom device comprising a front lens group and a rear lens group, wherein the rear lens group is driven by a stepping motor. In a camera having the following, when the focal length becomes the longest during zoom operation, the rear group lens is arranged at the home position where the rear group lens comes closest to the front group lens,
It is characterized in that it is provided with a control means for controlling the driving of the stepping motor and a detection means for detecting that the rear group lens is arranged at the home position.

Further, according to the present invention, when the stepping motor is driven by the control means, and the detection means detects that the rear lens group is not located at the home position, a means for operating only a predetermined switch is provided. It is characterized by being provided. As such a switch, a main switch of the camera, a back cover switch that is turned on and off in conjunction with opening and closing of the back cover, and a forced rewind switch for forcibly rewinding the film can be considered.

[0014]

[Function] When the focal length is maximized during zoom operation,
That is, when the front lens group is moved to the telephoto end, the rear lens group is located closest to the home position. Therefore, in the present invention, at this time, the rear lens group is moved to the home position to perform the home position check.

If an abnormality is detected in the home position check, only a predetermined switch such as the main switch is made to function and the input of the other switches is invalidated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

The two-group type zoom device of the camera to which the present invention is applied is the same as that described above with reference to FIG. 1, but its configuration is further improved in order to clarify the contents of the present invention. It will be described in detail.

The lens barrel 4 of the zoom device 2 includes a fixed barrel 6 forming a part of the camera body, an intermediate barrel 8 nestably housed in the fixed barrel 6, and a nestable barrel in the intermediate barrel 8. It has a triple structure composed of the movable barrel 10 housed in.

A spiral groove 12 is formed on the inner surface of the fixed barrel 6, and an engaging portion 14 provided on the outer surface of the end portion of the intermediate barrel 8.
Are engaged in the spiral groove 12. The intermediate cylinder 8 can be rotated in both forward and reverse directions by a DC motor (not shown) via a transmission mechanism 16, and is expanded and contracted with respect to the fixed cylinder 6 by the rotation.

A spiral groove 18 is also formed on the inner surface of the intermediate cylinder 8, and the engaging portion 20 on the outer surface of the end portion of the movable cylinder 10 is engaged with the spiral groove 18. Since the movable barrel 10 is not rotatable with respect to the fixed barrel 6, when the intermediate barrel 8 is rotated, it is expanded and contracted in the same direction as the expansion and contraction of the intermediate barrel 8.

A front lens group 22 is fixed to the tip of the movable barrel 10. Therefore, the front lens group 22 is moved back and forth by controlling the drive of the DC motor to expand and contract the intermediate cylinder 8 and the movable cylinder 10. Therefore, this DC motor functions as a driving motor for the front lens group 22.
Incidentally, reference numeral 24 is a position sensor for detecting the position of the movable member 26 which moves integrally with the intermediate barrel 8, but the position of the front lens group 22 is uniquely determined by the position of the intermediate barrel 8. Since it is determined, the position of the front lens group 22 can be detected at any time by the output signal from the position sensor 24.

The front lens group 22 is provided in the movable barrel 10.
A rear lens group 28 is disposed behind (on the camera body side) so as to be movable back and forth. Although not shown clearly in FIG.
Inside the moving barrel 10, a two-phase stepping motor is arranged as a rear lens group driving motor, and the feed screw 30 connected to the rotation shaft of the stepping motor is attached to the feed screw 30.
A female screw member 34 integrated with the lens frame 32 of the rear lens group 28.
Are screwed together. Therefore, the rear lens group 28 is moved back and forth by controlling the driving of the stepping motor.

The rear group lens 28 has a home position at a position closest to the front group lens 22, and the moving barrel 1
Inside 0, a home position sensor (not shown) for detecting that the rear lens group 28 is in this home position is provided. The position of the rear lens group 28 is calculated by the cumulative number of pulses of the pulse signal applied to the stepping motor with the home position as a reference. Although various types of home position sensors can be used, in this embodiment, a limit switch is used and the rear lens group 28 is used.
This limit switch is turned on when is placed in the home position.

As shown in FIG. 2, the control device of the camera having such a zoom device 2 is mainly composed of a CPU 40. The DC motor 42 for driving the front lens group 22 or the lens barrel 4 and the stepping motor 44 for driving the rear lens group 28 are arranged in the CPU 40 as a logic circuit.
It is connected through the driver circuit 46. logic·
The driver circuit 46 responds to a signal from the CPU 40,
By appropriately applying a high voltage and a low voltage to the DC motor 42, the rotation and braking of the motor 42 can be controlled. A pulse signal is issued from the CPU 40 to the stepping motor 44 in accordance with the excitation patterns shown in the table below, and the A phase and the B phase of the stepping motor 44 are appropriately excited.

In the table below, there is a rear lens group pointer, which is RAM data, and the CPU 40 uses the rear lens group 2
When 8 is moved to the next phase, each phase of the stepping motor 44 is excited with an excitation pattern according to the value of the rear group pointer. FIG. 3 is a conceptual diagram of the configuration and operation of the stepping motor 44 used in the camera of this embodiment. FIGS. 3A to 3D show rear group pointers “0” to “3”, respectively. It shows the state. As is clear from FIG. 3, when the pulse signal is output in the circulation pattern in which the value of the rear group pointer is increased by 1 point from “0” to “3” and then returns to “0” again, the stepping motor 4
The rotor 45 of No. 4 rotates in the forward rotation direction, and the rear lens group 28
Moves rearward, that is, in the direction away from the front lens group 22. Further, in the circulation pattern in which the value of the rear group pointer is decreased by 1 point from "3" to "0" and then returned to "3" again, the stepping motor 44 rotates in the reverse direction,
The rear lens group 28 moves forward. The states shown in FIGS. 3A and 3C are called static stable states, and even if the excitation is stopped in this state, the rotor 45 is in a stable state and does not rotate unless external force is applied. On the other hand, the states of (b) and (d) of FIG. 3 are called dynamic stable states because the rotor 45 rotates to the position of (a) or (c) of FIG. 3 when the excitation is stopped.

[0026]

[Table 1]

A switch section 48 is connected to the CPU 40. The switch unit 48 includes a main switch (SM), a back cover switch (SB), a shutter switch interlocking release switch (SP1, SP2), a self-timer switch (SSELF), a strobe mode switch (SMODE), and a forced rewind switch. (SMR), INF switch (SINF) for shooting a distant view, and zoom switch (STEL) for zooming to the telephoto side.
E), a zoom switch (SWIDE) for performing a zoom operation on the wide angle side, etc. are included, and ON / OFF signals of these switches are input to the CPU 40.

Further, the position sensor 24 for detecting the position of the front lens group 22 and the home position sensor 36 for detecting the home position of the rear lens group 28 are CPU4.
It is connected to 0.

Furthermore, a battery 50 is connected to the CPU 40 via a regulator circuit (REG circuit) 52. The battery 50 also functions as a drive power source for the zoom device 2. A battery check circuit (BC circuit) 54 is connected to the battery 50, and the CPU
The control signal from the battery 40 is used to check the battery voltage such as the voltage of the battery 50, and the information is input to the CPU 40.

Next, the control for the home position check according to the present invention will be described with reference to FIGS.

First, FIG. 4 is a flow chart from the loading of the film into the camera to the standby state (shootable state). That is, the main switch (SM) is O
N (step 101), the back cover is closed and the back cover switch (SB) is ON (step 102), and the forced rewind switch (SMR) is OFF. (Step 103), the shutter button is not pressed, the release switch (SP1) is OFF (step 104), the telephoto zoom switch (STELE) is OFF (step 105), wide angle Zoom switch (SWID
E) is OFF (step 106), self-timer switch (SSELF) is OFF (step 107), and strobe mode switch (SMODE) is OFF (step 1)
08) and that the INF switch (SINF) is OFF (step 109) are sequentially determined, and when all the above conditions are satisfied, the camera is set to the standby state. Once in the standby state, step 101
~ Step 109 is repeated.

When the telephoto zoom switch (STELE) is pressed after the camera has been put into the standby state in this way, the telephoto side zoom processing detailed in FIG. 5 is executed (step 110).

In this telephoto side zoom process, first, a battery check (BC) process is performed to make the battery 50
Is measured (step 201), and it is determined whether the voltage is less than or equal to a predetermined value (step 202). Then, when the voltage is equal to or lower than the predetermined value, the process proceeds to step 213,
This process is completed after waiting for the telephoto zoom switch (STELE) to be turned off.

When the voltage of the battery 50 is higher than a predetermined value,
That is, when it is determined that the position is within the normal range, the position of the front lens group 22 is detected by the signal from the position sensor 24 (step 203). If it is determined in step 204 that the position of the front lens group 22 is not equal to or greater than the wide (WIDE) end and less than the tele (TELE) end, it is determined that further zoom operation cannot be performed, and the process proceeds to step 213. Then, the process ends. That is, when the position of the front lens group 22 is at the telephoto end (the most telephoto state shown in FIG. 1A in which the lens barrel 4 is extended the longest), the zoom operation to the telephoto side is performed further. I can't. In addition, even when the camera is in the standby state, it may be located closer to the camera body than the wide end (the widest angle state shown in FIG. 1B in which the lens barrel 4 is most shortened in the standby state). Since it is considered abnormal, step 2
Move to 13.

When the front lens group 22 is located between the wide end and the telephoto end, the DC motor (front group motor) 42 for driving the front group lens is driven to move the front group lens 22 in the telephoto direction, that is, to the front. (Step 205). Then, the driving direction is set to the telephoto direction (TELE) (step 2
06).

After this, the telephoto zoom switch (STEL
Until E) is turned off or the front lens group 22 reaches the tele end, drive processing of the rear group lens drive stepping motor 44 (rear group drive processing) and position detection of the front lens group 22 (front group). (Position detection) is repeated (step 207)
~ 210). During this period, the DC motor 4 for driving the front lens group
2 is continuously driven.

The rear lens group driving process will be described with reference to FIG.

First, immediately after the DC motor 42 starts to be driven, the routine proceeds from step 301 to step 302, the timer is started, and after the elapse of a fixed time (100 ms in this embodiment), the front group motor drive flag is set. (Steps 303 and 304). Then, the rear group phase output processing is performed so that the stepping motor 44 has a phase corresponding to the value of the rear group pointer written in the RAM (step 305).

In the rear group phase output processing, as shown in FIG. 7, a predetermined pulse signal is output and stepping is performed in order to set the phase of the stepping motor 44 according to the value of the rear group pointer (see FIG. 3). Each phase of the motor 44 is appropriately excited.

After that, the position of the front lens group 22 is detected (step 208), and the rear lens group drive process is performed again (step 207). Here, since the front group motor drive flag has already been set, steps 301 to 3
Move to 06, 307.

Step 307 is stepping motor 4
4 is driven by N pulses, where N is step 3
In 06, it corresponds to the numerical value set in the rear group drive counter. In this step, since "1" is set in the rear group drive counter, the stepping motor 44 is driven by one pulse, and the rear group lens 28 moves in the telephoto direction by a distance corresponding thereto.

The processing of step 307 is shown in detail in the flowchart of FIG. In this process, first, since the driving direction is set to the telephoto direction (TELE), the process proceeds from step 401 to step 402.
When the rear group cumulative pulse number corresponding to the position of the rear group lens 28 is “0”, this means that the rear group lens 28 is at the reference position and is closest to the front group lens 22. Therefore, it is determined that no further movement in the telephoto direction is possible, and this processing ends.

On the other hand, when the rear group cumulative pulse number is "1" or more, the rear group lens 28 is moved forward by one pulse, so "1" is subtracted from the rear group cumulative pulse number in advance. (Step 403). Next, "1" is subtracted from the value of the rear group pointer corresponding to the current phase of the stepping motor 44 (step 404), and the subsequent step 407.
The stepping motor 44 is driven to the next phase with.
When the value of the rear group pointer becomes negative, "3" is set as the value of the rear group pointer (steps 405, 4).
06).

When a pulse signal corresponding to the value of the rear group pointer is output in step 407, the rotor 45 of the stepping motor 44 rotates in the reverse direction and the rear group lens 28 moves in the telephoto direction, as described above. Then, after waiting for a certain period of time (steps 408 and 409), "1" is subtracted from the value of the rear group drive counter (step 41).
0). As a result, the value of the rear group drive counter becomes "0", and this processing ends (step 411).

After the rear lens group driving process and the front lens group position detecting process (steps 207 and 208) are repeated, if the telephoto zoom switch (STELE) is turned off, the front lens group 22 is set to the desired position. In order to surely stop at the position, the DC motor 42 is braked (step 211). Then, the rear group driving process (step 20
The front group motor drive flag set in 7) is cleared (step 212), and the telephoto zoom switch (STELE)
Check that is turned off (Step 21
3) Then, the telephoto side zoom process ends.

On the other hand, according to the present invention, when the front lens group 22 reaches the tele end, the rear lens group 28 is used.
The process moves to the home position check process (steps 209, 214 to 219). In this process, first, in order to surely stop the front lens group 22 at the telephoto end,
Execute front group motor brake processing (step 21)
4). Thereafter, in order to bring the stepping motor 44 into a static stable state, the value of the rear group pointer at that time is detected, and it is detected whether or not it is an odd number (step 215).
As described above, in this embodiment, when the value of the rear group pointer is "0" or "2", the stepping motor 44 is in the static stable state, and when it is "1" or "3", the stepping motor 44 moves. Will be in a stable state. Therefore, when the value of the rear group pointer is an odd number, that is, "1" or "3", the rear group drive counter is set to "1" in step 216, and the rear group N pulse drive processing is executed in step 217. Then, the stepping motor 44 is driven by one pulse. This rear group N pulse drive processing is the processing shown in FIG. When the stepping motor 44 is driven by one pulse in this way, the stepping motor 44 is in a static stable state.

When the stepping motor 44 is in the static stable state, or when the value of the rear group pointer is "0" or "2" from the beginning and the stepping motor 44 is in the static stable state, the stepping motor 44 is set to the static stable state. In that state, the next rear group HP drive process is executed (step 21).
8).

The rear group HP driving process is a process for checking the home position, and as will be understood from FIG.
When the rear group lens 28 is moved to the home position and the limit switch, which is the home position sensor, is not turned on, it is determined that there is an abnormality and the HP detection error flag is set. This process will be described in more detail with reference to FIG.

First, after clearing the HP check drive counter indicating the number of drive processes (rear group N pulse drive process) applied to the stepping motor 44 for driving the rear lens group 28 (step 501), the rear group The driving direction of the stepping motor 44 is set to the reverse direction so that the driving direction of the lens 28 is the front lens group 22 side, that is, the front side (step 502). Then, as a precaution, the HP detection error flag is also cleared (step 503).

Next, in order to excite the stepping motor 44 in a phase corresponding to the value of the rear group pointer at that time, rear group phase output processing is performed (step 504). In the subsequent step 505, in order to stabilize the excitation state of the stepping motor 44, a waiting time of a certain time, in this embodiment about 10 ms, is provided.

After that, a process for driving the stepping motor 44 by N pulses is performed (steps 506 to 50).
8). Here, N corresponds to the numerical value set in the rear group drive counter in step 506. Therefore, in this processing, the rear group drive counter is set to "4", and therefore steps 401 to 411 are repeated four times in the processing of FIG. 8, the stepping motor 44 is driven by four pulses, and the rear group lens 28 Moves forward by a distance equivalent to that.

After this, if the group N pulse drive processing is completed, the home position sensor 36 is turned off after 10 ms.
N / OFF is detected (steps 509 to 512). In this embodiment, even if the home position sensor 36 is turned on for the first time, there is a possibility of malfunction, so it is decided to detect ON / OFF of the home position sensor 36 again after 2 ms.

When the home position sensor 36 is OFF, it is determined whether or not the value of the HP check drive counter is "180" or less (step 513). "1" is added to this HP check drive counter every time the stepping motor 44 is driven by four pulses (step 507), but the value of this counter is "18".
If it is "0" or less, there is a possibility that the rear lens group 28 has not yet reached the home position. this is,
This is because it is necessary to send the pulse signal to the stepping motor 44 720 times (180 counters) to move the rear lens group 28 from the position farthest from the home position to the home position. If the home position sensor 36 is OFF and the HP check drive counter is "180" or less, it can be considered that the rear lens group 28 has not reached the home position, and therefore steps 506 to 512 are executed. I will repeat. Then, the home position sensor 36 is turned off.
And the HP check drive counter is "180".
If it exceeds, it is considered that there is an abnormality in the driving of the rear lens group 28, the HP detection error flag is set (step 514), and this processing is exited.

On the other hand, when the value of the HP check drive counter is within "180", the home position sensor 36 is turned on.
If it is set, the rear lens group 28 is moved to the standby position separated from the home position by a few pulses toward the camera body. Here, in order to move by 8 pulses, first, the drive direction of the stepping motor 44 is set to the forward rotation direction (step 515), and "8" is set to the rear group drive counter (step 516). Then, after performing the rear group N pulse drive processing (step 517), about 1
After waiting 0 ms, the excited state of the stepping motor 44 is stabilized (step 518). In the rear group N pulse drive process, the process proceeds from step 401 to step 412 in FIG. 8 and steps 401 to 411 are repeated eight times.

When the rear lens group 28 is moved to the standby position in this way and there is no abnormality, the home position sensor 36 is turned off. However, even if the ON / OFF detection of the home position sensor 36 is performed twice (steps 519 to 521), if the home position sensor 36 remains ON, it is determined that some abnormality has occurred and HP detection is performed. The error flag is set (step 514).

If the home position sensor 36 is OFF in steps 519 to 521, this is normal, and therefore the HP detection error flag is not set and
After this, the group HP drive processing is exited.

After this, an abnormality was discovered in the group HP drive processing,
When the HP detection error flag is set, the process proceeds to error processing (steps 219 and 220). This HP
When the detection flag is set, there is an abnormality in the operation of the stepping motor 44 or other elements, and RA
Rear group lens 28 obtained from the cumulative number of pulses which is M data
Since the position of and the actual position are different, there is a high possibility that the focus will not be achieved even if the exposure process is performed thereafter. Therefore, in the error processing, as shown in FIG. 10, a switch unrelated to the shooting processing, for example, the main switch (S
M), the back cover switch (SB), and the forced rewinding switch (SMR) only function. As a result, even if the main switch (SM) is turned off and the lens barrel 4 is housed in the camera body, or the film is forcibly rewound to the paltone and taken out from the camera body, zoom operation or Exposure and the like cannot be performed.

On the other hand, if the HP detection error flag is not set in the rear group HP drive processing, it is determined that the drive lens 28 is normally driven, and step 219 is performed.
From step 212 to step 213, the process returns to the standby state.

If the rear group lens 28 is placed at the home position in the rear group HP drive processing so that the cumulative pulse number is cleared, the stepping motor 4
Even if there is a slight step-out on the front lens group 4, the front lens group 22
Is effective because the normal state is restored each time the tele end reaches.

The preferred embodiments of the present invention have been described above in detail, but it goes without saying that the present invention is not limited to the above embodiments. For example, in the above embodiment, the switches that can function in the error handling are limited to the main switch (SM), the back cover switch (SB), and the forced rewind switch (SMR), but other switches are included. May be.

In the above embodiment, the stepping motor 4 is used.
4 and the DC motor 42 are simultaneously driven, the stepping motor 44 and the DC motor 42
The present invention is also applicable to a system in which are driven alternately.

[0062]

As described above, according to the present invention, the home position of the rear lens group is checked even during zoom operation, so that the operation accuracy of the zoom device is improved and problems such as defocusing can be prevented. You can

Further, when an abnormality is detected by the home position check, the switch is limited, so that photographing is not repeated in the abnormal state, and deterioration of the failure can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a two-group type zoom device of a camera to which the present invention is applied, FIG.
(B) shows the widest angle state.

FIG. 2 is a block diagram showing a CPU constituting a control device according to the present invention.

FIG. 3 is a conceptual diagram showing a configuration and operation of a stepping motor for driving a rear group lens of a zoom device.

FIG. 4 is a flowchart showing an example of processing until the camera reaches a standby state.

FIG. 5 is a flowchart showing an example of a telephoto side zoom process executed by the control device of the present invention.

FIG. 6 is a flowchart showing an example of a rear group drive process executed by the control device of the present invention.

FIG. 7 is a flowchart showing an example of a rear group phase output process executed by the control device of the present invention.

FIG. 8 is a flowchart showing an example of a rear group N pulse drive processing executed by the control device of the present invention.

FIG. 9 is a flowchart showing an example of a rear group HP drive process executed by the control device of the present invention.

FIG. 10 is a flowchart showing an embodiment of error processing executed by the control device of the present invention.

[Explanation of symbols]

2 ... 2 group type zoom device, 4 ... lens barrel, 6 ... fixed barrel,
8 ... Intermediate barrel, 10 ... Moving barrel, 16 ... Transmission mechanism, 22 ... Front group lens, 24 ... Position sensor, 28 ... Rear group lens, 36 ... Home position sensor, 40 ... CPU, 4
2 ... DC motor, 44 ... Stepping motor, 46 ... Logic driver circuit, 48 ... Switch section, 50 ... Battery, 52 ... Regulator circuit, 54 ... Battery check circuit.

Claims (3)

[Claims] 1. A zoom device comprising a front lens group and a rear lens group, wherein the rear lens group is driven by a stepping motor, wherein the focal length is longest during zoom operation. When the rear lens group becomes closer to the front lens group, the rear lens group is arranged at a home position where the rear lens group comes closest to the front lens group. A control device for a camera, comprising: a detection unit that detects that the camera is placed at a position. 2. A means for causing only a predetermined switch to function when the detection means detects that the rear lens group is not arranged at the home position when the stepping motor is driven by the control means. The camera control device according to claim 1, further comprising: 3. The predetermined switch is a main switch of the camera, a back cover switch that is turned on and off in association with opening and closing of the back cover, and a forced rewind switch for forcibly rewinding the film. The control device for the camera according to claim 2.