JPH06324248A - Controller for zoom device - Google Patents

Abstract

PURPOSE:To prevent the step out of a stepping motor for driving a rear group lens which occurs at the time of finishing zooming operation in a zoom device of two-groups. CONSTITUTION:This controller is applied to the zoom device constituted of a front group lens driven by a DC motor 42 and a rear group lens driven by the stepping motor 44. At the time of finishing the zooming operation, it is quite possible that the stepping motor 44 is in a dynamic state, but the step out is prevented from occurring after stopping energizing by moving the stepping motor 44 to a static stable state in the midst of the braking processing of the DC motor in such a case.

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 two-group type zoom device composed of a front lens group and a rear lens group, and more particularly to a motor control means during zoom operation.

[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 such a mechanism, a DC motor is used as a motor for driving the front lens group, and a stepping motor is used as a motor for driving the rear lens group. In addition, as a drive system thereof, it is general to adopt a so-called simultaneous drive system in which a stepping motor is driven in units of several pulses during continuous drive of a DC motor.

[0004]

By the way, in a stepping motor used for a zoom device of a camera, a rotor is arranged at either a static stable position or a dynamic stable position according to an excitation state of each phase. Is configured. When the rotor is in the static stable position (static stable state), the rotor remains in that position even when the excited state is released. However, when the rotor is in the dynamic position (dynamic state), when the excited state is released, the rotor may rotate to the static stable position.

Since the stepping motor has such a characteristic, in the conventional simultaneous driving method as described above, the stepping motor may be in a dynamic state when the zoom operation is completed. In such a case, if the stepping motor is de-energized and the excited state is released, the rotor of the stepping motor may rotate to a static stable position. The position of the rear lens group is obtained from the cumulative number of pulses of the pulse signal applied to the stepping motor, so when the rotor of the stepping motor rolls, the position of the rear group lens obtained from the cumulative number of pulses and the actual position are calculated. Will be different.

If such a positional shift, that is, a so-called step-out occurs, even if the rear lens group is driven to the focusing position during exposure, it is not arranged at a desired position, and there is a problem that it is out of focus.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a simultaneous drive type control device which does not cause step-out even if power supply to a stepping motor is stopped at the end of zoom operation. To do.

[0008]

In order to achieve the above object, when the stepping motor is in a dynamic state at the end of the zoom operation, the stepping motor is energized after a static stable state. It is possible to stop.

However, due to this processing, if the shift to the next sequence is delayed, there is a possibility that a photo opportunity may be missed.

Therefore, the control device according to the present invention comprises a front lens group driven by a DC motor and a rear lens group driven by a stepping motor. The zoom motor operates the stepping motor during continuous driving of the DC motor. It is applied to a zoom device that is driven in units of several pulses, and when the stepping motor is in a dynamic state at the end of the zoom operation, from when the braking process of the DC motor is started until the DC motor is stopped. It is characterized in that a means for bringing the stepping motor into a static stable state is provided therebetween.

[0011]

In the zoom device to which the present invention is applied, since the stepping motor is driven in units of several pulses such as one pulse during simultaneous driving, the stepping motor is in either a static state or a dynamic state at the end of the zoom operation. become. As described above, it is not preferable to keep the stepping motor in the dynamic state, so in the control device of the present invention, when the stepping motor is in the dynamic state at the end of the zoom operation, it is set to the static stable state, and The process is performed during the braking process of the DC motor for driving the front lens group.

[0012]

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

FIG. 1 shows a two-group type zoom device 2 of a camera to which the present invention can be applied. The lens barrel 4 of the zoom device 2 includes a fixed barrel 6 fixed to a camera body (not shown), an intermediate barrel 8 nestably housed in the fixed barrel 6, and a nest in the intermediate barrel 8. It is composed of a movable cylinder 10 that is housed in a manner.

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 an 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 from 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 lens group 28 is provided with a home position sensor (not shown) for detecting that the rear lens group 28 is at a reference position determined with respect to the movable barrel 10. And
The position of the rear lens group 28 is calculated by the pulse number of the stepping motor driven from the reference position.

As shown in FIG. 2, the control device of the present invention applied to the zoom device 2 having the above-mentioned structure is mainly composed of a CPU 40. The DC motor 42 for driving the front lens group 22 and the stepping motor 44 for driving the rear lens group 28 are provided to the CPU 40 by a logic driver circuit 46.
Connected through. Logic driver circuit 46
Can appropriately apply a high voltage and a low voltage to the DC motor 42 according to a signal from the CPU 40 to control rotation and braking of the DC motor 42. For example, when a high voltage of the same potential is applied to both terminals of the DC motor 42, the motor 42 is braked. Then, by applying a low voltage of the same potential to both terminals, the motor 42 can be held in a stopped state.

Further, 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 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 causes the rear lens group 2 to move.
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 (a) and (c) of FIG. 3 are called statically stable states. Even if the excitation is stopped in this state, the rotor 45 is stable and does not rotate unless external force is applied. On the other hand, (b) and (d) of FIG.
In this state, when the excitation is stopped, the rotor 45 moves to (a) in FIG.
Or, because it rotates to the position of (c), it is called a dynamic state.

[0022]

[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, 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 40
A battery check for the voltage of the battery 50 and the like is performed by a control signal from the CPU, and the information is input to the CPU 40.

Further, a position sensor 24 for detecting the position of the front lens group 22 and a home position sensor 36 for detecting the reference position of the rear lens group are connected to the CPU 40.

Next, referring to FIG. 4 to FIG.
The control of the zoom device 2 by U40 will be described.

First, FIG. 4 is a flow chart from the loading of the film into the camera to the standby state. That is, the main switch (SM) is ON (step 101), the back cover is closed and the back cover switch (SB) is ON (step 10).
2) The forced rewind switch (SMR) is off (step 103), the shutter button is not pressed and the release switch (SP1) is off (step 104), and the telephoto zoom The switch (STELE) is OFF (Step 1
05), wide-angle zoom switch (SWIDE) is OFF
(Step 106), the self-timer switch (SSELF) is OFF (step 107), the strobe mode switch (SMODE)
Is OFF (step 108), INF
It is sequentially determined that the switch (SINF) is OFF (step 109), and if all the above conditions are satisfied, the camera is placed in the standby state. Once in the standby state, step 101 to step 10
Repeat 9.

When the telephoto zoom switch (STELE) is pressed after the camera has been put in 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 state in which the lens barrel 4 is extended the longest, as shown in FIG. 1A), further zoom operation to the telephoto side cannot be performed. . In addition, even when the camera is in the standby state, it is also abnormal when it is located closer to the camera body than the wide end (the state in which the lens barrel 4 is most shortened in the standby state, as shown in FIG. 1B). Since it is considered, the process proceeds to step 213.

When the front lens group 22 is between the wide end and the telephoto end, the DC motor (front group motor) 42 for driving the front lens group is driven to move the front lens group 22 in the telephoto direction, that is, the front direction. (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 a lapse 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 process, as shown in FIG. 7, a predetermined pulse signal is output to set the phase of the stepping motor 44 (see FIG. 3) according to the value of the rear group pointer, and the stepping is performed. Each phase of the motor 44 is appropriately excited.

After this, the position of the front lens group 22 is detected (step 208), and the rear lens group driving 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).

In this way, the front lens group 22 reaches the telephoto end, or the telephoto zoom switch (STELE)
Is turned off (steps 209 and 21 in FIG. 5).
0), in order to surely stop the front lens group 22 at a desired position, the DC motor 42 is braked (step 211).

In this embodiment, the stepping motor 44
Is driven in a unit of one pulse, the rotor 45 thereof has a static stable position ((a) and (c) in FIG. 3) and a dynamic position ((b) and (c) in FIG. 3) during the zoom operation. )) Are arranged alternately. Therefore, just before the braking process,
The stepping motor 44 may be in a dynamic state.

Therefore, in the present invention, when the rotor 45 of the stepping motor 44 stops at the dynamic position, the rotor 45 is rotated to the static stable position during the braking process.

FIG. 9 shows the procedure in the braking process in detail. As shown in the figure, first, the energization of the front group motor 42 is temporarily stopped (step 501), and then, in order to forcibly stop the front group motor 42, a brake signal is output to the logic driver circuit 46. A high voltage of the same potential is applied to both terminals of the motor 42 (step 5
02).

In the configuration of this embodiment, it is known that the front group motor 42 is completely stopped within 50 ms after the brake signal is output. Therefore, after outputting the brake signal, the brake timer set to 50 ms is started (step 503). Then, a process of unifying the state of the stepping motor 44 into a static stable state is performed by the time 50 ms has elapsed after the start of the brake timer (steps 504 to 507).
First, it is detected whether or not the value of the rear group pointer at that time is an odd number (step 504). 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. It becomes a target state.
Therefore, when the value of the rear group pointer is an odd number, that is, "1" or "3", the stepping motor 44 is changed from the dynamic state to the static stable state.

In order to bring the stepping motor 44 into a static stable state, the rear group drive counter is set to "1" in step 505, and the rear group N is set in step 506.
The pulse driving process is executed to drive the stepping motor 44 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 rotor 45 thereof is arranged at the static stable position. Of course, even if the numerical value set in the rear group drive counter in step 505 is an odd number of 3 or more, the stepping motor 44 will be in a static stable state. However, in order to minimize the movement of the rear lens group 28, the set value at this time is preferably "1" or "3".

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. The state is maintained and the process waits until the set time of the brake timer elapses (step 507). Finally, in order to hold the DC motor 42 in a stopped state, a motor holding signal is output to the logic driver circuit 46 and a low voltage of the same potential is applied to both terminals of the DC motor 42 (step 508).

Since the stepping motor 44 is in a static stable state after the front group motor braking process is completed in this way, even if the energization of the stepping motor 44 is stopped after that, the rotation of the stepping motor 44 is stopped. Child 45
Does not rotate, preventing step-out. Further, since the process of changing the stepping motor 44 from the dynamic state to the static stable state is also performed during the braking process of the DC motor 44, the time required for the entire zoom operation process does not increase.

When the front group motor braking process is completed, the front group motor drive flag previously set in the rear group drive process (step 207) is cleared (step 21).
2) Then, it is confirmed that the telephoto zoom switch (STELE) is turned off (step 213), and the telephoto side zoom process is ended.

Although the above embodiment relates to the zoom operation on the telephoto side, the zoom operation to the wide angle side is also processed in substantially the same flow.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. For example, it will be easily understood by those skilled in the art that the type of stepping motor, the excitation pattern, and the like differ depending on the zoom device, but the processing procedure is changed accordingly.

[0052]

As described above, according to the present invention, the stepping motor does not enter a dynamic stable state at the end of the zoom operation, and therefore, even if the stepping motor is de-energized, step-out occurs. There is no. Therefore, the position of the rear lens group is always accurately grasped by the CPU, and the zoom device can be operated properly. For example, when the exposure process is performed after the zoom operation is completed, the rear lens group can be reliably arranged at the focusing position, and the occurrence of blurring can be prevented.

Further, since the process of changing the stepping motor from the dynamic state to the static stable state is also performed during the braking process of the DC motor, it does not affect the processing time of the entire zoom operation. Therefore, the time required to move from the zoom operation to the next sequence is no different from the conventional configuration.

[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, in which (a) shows the most telephoto state and (b) shows the most wide-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 front group motor brake process 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 (1)

[Claims] 1. A zoom device comprising a front lens group driven by a DC motor and a rear lens group driven by a stepping motor, wherein the stepping motor is operated during continuous driving of the DC motor during zoom operation. In a zoom device that is driven in units of several pulses, when the stepping motor is in a dynamic stable state at the end of the zoom operation, from when the braking process of the DC motor is started until the DC motor is stopped A control device for a zoom device, characterized in that a means for bringing the stepping motor into a static stable state is provided between the two.