JPH10282395A - Pulse motor drive device of camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse motor drive device of a camera in which the necessary accuracy of a pulse motor of 1-2 phase excitation drive type can be obtained while the power consumption is reduced. SOLUTION: Zoom lenses having a fixed first lens group L1, a movable second lens group L2, and a movable third lens group L3, a motor M1 for stop to open/close the stop of the zoom lenses, and a pulse motor M2 for second group to move the second lens group L2 are provided, the pulse motors M1, M2 comprise the pulse motors of 1-2 phase excitation type, a lens side control circuit 70 drives and stops the pulse motors M1, M2 with one-step angle unit during the photographing while the pulse motors M1, M2 are driven with the odd-numbered step angle unit otherwise, and constantly stops the motors at the detent position to cut off the excitation of the pulse motors M1, M2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor, and more particularly to a driving device for a pulse motor mounted on a digital still camera.

[0002]

2. Description of the Related Art A motor is used for an automatic focusing mechanism in a recent camera. In the case of a DC motor, as a means for detecting the position of the focus adjustment lens, a relative position detecting means for detecting a relative position from a reference position by an encoder or the like is known. When this encoder is used, a space for accommodating the encoder is required, and a means for detecting the output of the encoder is also required.

[0005] Therefore, it is conceivable to use a pulse (stepping) motor capable of stepwise controlling the rotation angle for the automatic focusing mechanism of the photographing lens. Large rotation torque,
The pulse motor of the 1-2 phase excitation method (half-step driving method) whose control circuit is relatively simple has a rotor where the rotor stops even in the non-excitation position and stops in the excitation state, but is adjacent when the excitation is turned off. It has a stable position (equilibrium position) where it rotates to any detent position and stops. Hereinafter, the excitation that stops at the detent position is called one-phase excitation, and the excitation that stops at the stable position is called two-phase excitation. That is, in the 1-2-phase excitation type pulse motor, when the excitation is cut off at the two-phase excitation position, the rotor rotates to one of the detent positions (one-phase excitation position) adjacent to the two-phase excitation position and stops. This is likely to cause an error in the stop position. Therefore, when stopping at the two-phase excitation position, the stable position cannot be maintained unless the two-phase excitation is maintained, but in this case, power consumption increases.

In recent years, what is called a digital camera or a digital still camera is a C-type digital camera instead of a silver halide film.
A CD imaging device is used. A CCD image sensor usually has a smaller latitude than a silver halide film, and requires precise exposure adjustment and focus adjustment at the time of photographing. However, other than when shooting, for example, the photographer
Alternatively, when observing with a liquid crystal display or the like, it is sufficient that the photographer does not feel blur.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the pulse motor, and is intended to reduce the power consumption of a 1-2-phase excitation drive pulse motor and obtain a required accuracy. The present invention provides a pulse motor drive control method.

[0006]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides a 1-2 phase excitation type pulse motor mounted on a camera.
A driving device for driving and stopping by phase excitation, wherein when the pulse motor is driven with high precision, when the pulse motor is stopped at the one-phase excitation position, the excitation is stopped at the one-phase excitation position to stop, and the two-phase excitation is performed. When stopped at a position, the excitation state is maintained and stopped, and when the pulse motor is not normally driven, drive control means is provided to always stop and stop excitation at a one-phase excitation position. Have. A pulse motor for moving the focusing lens of the taking lens,
Alternatively, when the present invention is applied to a pulse motor that drives the opening and closing of the aperture of a photographic lens, the high-precision driving is performed during photographing, and the normal driving is performed except during photographing. Furthermore, CCD
When mounted on a digital camera equipped with an image sensor, a memory means for storing image data captured by the CCD image sensor, and a liquid crystal display for displaying the image data, the digital camera includes When the image data is displayed on the liquid crystal display but is not recorded in the memory, the normal driving is performed. According to these configurations, it is possible to perform high-precision positioning in units of one step angle at the time of shooting requiring high accuracy, and to stop at the detent position at every other step angle when high accuracy is not required except during shooting. Power consumption can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a digital camera having a power zoom lens. Although not shown in detail, the digital camera includes a zoom lens unit including a power zoom lens, a CCD image pickup device, and the like, an image storage device such as a flash memory, and a camera unit including a color liquid crystal display. .

The configuration of the lens control system of the zoom lens unit will be described with reference to FIG. The zoom lens unit includes a fixed first lens unit L1, a movable second lens unit L3, and a third lens unit L3 as a lens system, and includes a lens-side control circuit (CPU) 70 that controls the entire zoom lens unit. I have. The lens-side control circuit 70 includes, as a 1-2-phase drive pulse motor, an aperture pulse motor M1 for driving an aperture, and a second lens group L2 for driving a zoom lens.
The group pulse motor M2 and the third group pulse motor M3 for driving the third lens group L3
6, 27 and 28 are connected. The pulse motors M1, M2, and M3 of the present embodiment are 1-2 phase excitation (half-step drive) type pulse motors.

The lens-side control circuit 70 further includes a second-group origin sensor 22 for detecting that the second lens unit L2 is at the origin position, and a third unit for detecting the absolute position of the third lens unit L3.
Group volume 40, aperture origin sensor 55 for detecting the aperture origin position (open position), color image sensor (CCD
An image sensor) 18, a zoom switch 71 having a tele switch and a wide switch, a release switch 72,
A photometric device 73 and a distance measuring device 74 for measuring the brightness of the subject are connected. The photometric device 73 is commonly used also as the CCD image pickup device 18, but is separately shown for the sake of notation. The distance measuring device 74 is not limited to a passive type or an active type, but the present embodiment is a passive type and detects a subject distance (photographing distance).

The CCD image pickup device 18 includes a CCD driver 7
7, the optical image information formed on the CCD image pickup device 18 is converted into an electric image signal and output to the signal processing circuit 75. The signal processing circuit 75 converts the input image signal into digital image data and records the digital image data in the image data storage device 76. Various storage media such as a built-in flash memory and a removable memory card are used as storage media for the image data storage device 76.

A battery 91 for supplying power to these electronic devices is mounted on a camera unit, and when a power switch 93 is turned on, via a DC / DC converter 92.
Alternatively, power can be directly supplied to each electronic device of the zoom lens unit, but these are assumed to be mounted on the zoom lens unit for the sake of simplicity. The power switch 93 is connected to the lens-side control circuit 70, and the lens-side control circuit 70 supplies power to each electronic device via the DC / DC converter 92 when the power switch 93 is turned on. Also, the power switch 93 of the present embodiment
The camera also functions as an imaging mode switch that takes an image when the release switch 72 is turned on and stores the digital image signal in the storage device 76.

As shown in FIGS. 2 to 5, the lens configuration of the zoom lens unit of this embodiment includes a fixed positive first lens unit L1, a movable negative second lens unit L2, and a positive third lens unit L2. This is a three-group configuration including a lens group L3. In this lens system, zooming (variable magnification) is performed by the second lens unit L2 and the third lens unit L.
Focusing is performed by moving the second lens unit L2, and focusing is a vari-focal type performed by moving the second lens unit L2. However, the relative position control between the second lens unit L2 and the third lens unit L3 is not performed by a cam groove. . Based on the set focal length information (position information of the second lens group L2) and the subject distance (photographing distance) information, the position of the second lens group L2 is controlled to be open, and the position of the third lens group L3 is controlled to be closed. It is. In the present embodiment, for the sake of simplicity, the second lens unit L2 is a focus adjustment lens group, the second group pulse motor M2 is a focus adjustment motor, the third lens group is a variable power lens group, The third group motor M3 will be described as a zoom motor for power zoom.

The pulse motors M1, M2, M3 of this embodiment
Is a 1-2 phase excitation pulse motor. Therefore, when the excitation is turned off, the motor stops at any one of the detent positions (one-phase excitation position). That is, if the excitation is turned off in the one-phase excitation state, the rotating shaft (rotor) stops at the detent position, and if the excitation is turned off in the two-phase excitation state, the rotation shaft (rotor) may stop at that position (equilibrium position). Tend to rotate to a detent position which is a one-phase excitation position on either side and stop at that detent position.

The number of pixels of a liquid crystal display mounted as a finder in a digital still camera is usually
The number is smaller than the number of pixels of the CCD imaging device 18. Therefore, even if a defocus exists at a few step angles in the number of step angles of the second group pulse motor M2, it is hardly perceived as defocus by the naked eye. On the other hand, the image data captured by the CCD image pickup device 18 is affected by the focus shift.
Similarly, in the case of the aperture, the exposure error is hardly perceived when the image is observed on the liquid crystal display, but the effect appears on the captured image data.

Therefore, in the embodiment of the present invention, when photographing, that is, when writing an image into the memory, the motor M
The motors M1 and M2 are normally driven in units of even-numbered step angles when high-precision driving is performed in units of one-step angle.

For example, when the release switch 72 is half-pressed or fully depressed, that is, at the time of photographing, the lens-side control circuit 70 adjusts the aperture value and the focus adjustment by one step angle (an integer) of the pulse motors M1, M2, M3. Number of pulses)
It is performed by high precision driving based on precision. That is, the pulse motor M
1, the number of drive pulses is set based on the aperture value that changes when M2 is rotated by one step angle and the moving distance of the second lens unit L2. On the other hand, when the release switch 72 is not turned on, the lens-side control circuit 70 performs the aperture value and the focus adjustment by the normal driving with the accuracy of the two step angles (even pulse number) of the pulse motors M1 and M2. In the present embodiment, the third group pulse motor M3 is mainly involved in the change of the focal length. Therefore, even if the third group pulse motor M3 is driven with the two-step angle accuracy, there is little possibility that the image data is adversely affected. Although driving is performed with angular accuracy, fine adjustment may be performed with one-step angular accuracy during shooting.

The overall structure of the zoom lens unit is shown in FIGS.
This will be described with reference to FIG. The lens barrel body 10 located in the lens side casing 11 is roughly divided into a front plastic body 12, a rear plastic body 13, and a portion between the front body 12 and the rear body 13, as is apparent from FIGS. And an aperture block 14 sandwiched between them. A plurality of guide rods 15 (only one is shown in FIG. 5) in a direction parallel to the optical axis are fixed between the front body 12 and the rear body 13.
The second group frame 16 holding the second lens group L2 and the third group frame 17 holding the third lens group L3 are movably guided. Behind the third group frame 17, a CCD
The image pickup device 18 is located, and the CCD image pickup device 18 is fixed to the rear body 13 via the substrate 20.
Reference numeral 19 denotes a crystal filter. A cover glass (parallel plane plate) 25 (FIGS. 2 and 3) located in front of the first lens unit L1 is fixed to the casing 11.

The second group frame 16 and the third group frame 17 are integrally provided with a second group pin 16a and a third group pin 17a which protrude upward. The second group frame 16 and the third group frame 17 are respectively provided with tension springs 16b, 1
7b, it is urged to move backward (toward the CCD image sensor 18).

A photosensor (origin sensor) 22 for detecting the origin position of the second group frame 16 (second lens group L2) is fixed to the front body 12.
Dog plate 23 cooperating with this photo sensor 22
Has been fixed. In this embodiment, the origin position of the second lens unit L2 is set as the infinity shooting position at the wide-angle end. When the second lens unit L2 is at this origin position, the dog plate 23 detects the photo sensor 22. Shield the light and detect the origin position. The amount of movement from this origin position is
The lens-side control circuit 70 manages the number of pulses of the second-group pulse motor M2 that moves the second lens group L2.
Note that the amount of movement from this origin is the second group pulse motor M2
Can also be managed based on the output of the pulsar using a pulsar linked to the pulsar.

FIG. 5 shows a state at the telephoto end. When the focal length changes from the telephoto end to the wide-angle end, the second group frame 16 (the second lens group L2) moves forward and the third group frame 17
(The third lens unit L3) moves backward. That is, when changing the focal length, the second group frame 16 (the second lens group L
2) and the third group frame 17 (third lens group L3) always move in opposite directions.

The second group frames 16 and 3 in the lens barrel body 10 described above.
The driving mechanism for driving the group frame 17 is the lens driving unit 3
As 0, it is separately assembled and mounted so as to straddle on the front body 12 and the rear body 13. Lower second master plate 32
On the lower surface, each output shaft is connected to the second master plate 32.
The second group pulse motor M2 and the third group motor M3 are fixed in a state orthogonal to. The first master plate 31 has a second group frame 1
The second group drive plate 35 having a cam groove (lead groove) into which the second group pin 16a of the sixth group is fitted, and the third group pin 17a of the third group frame 17
Drive plate 3 having a cam groove (lead groove) into which the groove is fitted
6 are coaxially pivoted on a common shaft 37. The second group pin 16a and the third group pin 17a are connected to respective tension springs 16b.
And 17b, the rear side of the cam groove (the CCD image pickup device 18
Side) is always in contact with the surface, and backlash is removed.

Between the first master plate 31 and the second master plate 32, two
A gear mechanism 38 for transmitting the rotation of the group pulse motor M2 to the second group driving plate 35, a gear mechanism 39 for transmitting the rotation of the third group pulse motor M3 to the third group driving plate 36, and a third mechanism driving plate 36 not shown. A volume mechanism (variable resistor) is supported. The lens-side control circuit 70 takes in the resistance value of this volume mechanism and converts it into position information of the third lens unit L3.

In FIG. 3, reference numeral 60 denotes the front body 1
The aperture driving unit drives the aperture block 14 sandwiched between the rear body 2 and the rear body 13. Aperture block 14
The front body 12 and the rear body 1
3 is fixed. The aperture block 14 includes a retainer 52 fixed to the substrate 50, an aperture blade 53, an opening / closing ring 54 for driving the aperture blade 53 to open and close, and an aperture origin sensor for detecting the origin position (maximum open position) of the aperture blade 53. As 55, a photo sensor (not shown) is provided. The lens side control circuit 70 detects the aperture origin position of the aperture block 14 (the aperture blade 53) via the photo sensor.

The iris drive unit 60 includes the iris block 1
Reference numeral 4 denotes another unit member that is fixed to the rear body 13 with the positions in the optical axis direction and the radial direction being different. An aperture pulse motor M1 is fixed to a substrate 61 of the drive unit 60, and a first gear 62a of an output shaft thereof is connected to a second gear 6a.
It meshes with the sector gear 62c via 2b. A radial arm 62d is provided integrally with the sector gear 62c, and an interlocking pin 63 that fits into the radial interlocking groove of the opening / closing ring 54 protrudes from the radius arm 62d.
That is, when the aperture pulse motor M1 rotates and the radius arm 62d rotates, the opening / closing ring 54 rotates and the aperture blade 5
3 is driven to open and close. The aperture pulse motor M1 stops at the detent position.

The lens-side casing 11 is rotatably connected to a body-side casing (not shown) through a substantially central cylindrical boss 81 (FIGS. 2 and 3) within a rotation angle range of less than 360 °. A liquid crystal display having a finder function for displaying a subject image formed on the CCD image pickup device 18 in addition to a zoom switch, a release switch, a signal processing circuit, an image data memory means,
It is possible to mount body side control means, various function switches, and the like. The electric circuit in the body-side casing and the electric circuit in the lens-side casing 11 are connected via a body-lens connection FPC board 82 passing through a cylindrical boss 81. That is, the body-lens connection FPC board 82 connected to the CPU in the body-side casing is connected to the cylindrical boss 8.
1 and is connected to a connector 83 provided on the board 20 and a connector 85 provided on the lens-side FPC board 84.
A printed circuit for connecting all the electric elements in the electronic device 1 and an electronic device such as a lens-side control circuit 70 are mounted.

The in-focus position of this zoom lens, that is, the second
The position of the lens unit L2 is uniquely determined by the position (set focal length) of the third lens unit L3 and the subject distance information measured by the distance measuring device 74. Therefore, the position of the second lens unit L2 (the number of driving pulses from the origin position) determined by the focal length and the subject distance is obtained in advance by calculation or by actual measurement, converted into table data, and written in, for example, the EEPROM 100. And
At the time of photographing, the table is read from the EEPROM 100 to set the position of the second lens unit L2, that is, the number of drive pulses from the origin position.

In one embodiment, this table is composed of a table 1 for one-step angle drive (for photographing) of high precision driving and a table 2 for two-step angle driving of normal driving (for other than photographing). Prepare two. In other words, the focus table 1 for high-precision driving includes the second group pulse motor M2
Are generated in an integer (in units of one), and the focus table 2 for normal driving is a second group pulse motor M2.
Are generated in even numbers (in units of two). Then, the focus table 1 is used when setting the number of drive pulses of the second group pulse motor M2 during shooting, and the focus table 2 is used when setting the number of drive pulses of the second group pulse motor M2 except during shooting.

Similarly, an appropriate aperture value based on the photometric value measured by the photometric device 73 and the aperture pulse motor M1
Is converted into table data, and when the aperture pulse motor M1 is driven, the number of drive pulses is read from this table and set. In this embodiment,
The number of drive pulses of the aperture pulse motor M1 is also the same as that of the second group pulse motor M2. The aperture table 1 for high-precision drive (for one-step angle drive) and the aperture table for normal drive (for even-step angle drive) 2, an aperture table 1 is used at the time of shooting, and an aperture table 2 is used except at the time of shooting.

In the case of driving at an even step angle, the set value can be obtained as an integer, and in the case of an odd number, it can be rounded down or rounded up. In general, in the case of a photographing lens, the depth of field is deeper on the far side than on the near side, and the CCD image pickup device may overflow and cause image collapse or smear when overexposed.
Therefore, in the case of the present embodiment, the second group pulse motor M2 is
Since the lens unit L2 is moved from the infinity in-focus position to the close-in-focus position, a round-up process is performed. Since the aperture pulse motor M1 drives the aperture blade 53 in a direction to close from the open position, the round-up process is performed.

Next, the control operation of the lens side control circuit 70 will be described. FIG. 6 shows a flowchart of an embodiment in which the photometry process and the focus adjustment process are repeatedly executed while the power switch 93 is on. In the present embodiment, while the power switch is turned on, the motors M1 and M2 are driven by an even-numbered step angle by normal driving,
It is characterized in that the motors M1 and M2 are driven one step angle by high precision driving when the release switch 72 is half-pressed. In this embodiment, the image data is written into the image data recording device 76 when the release switch 72 is fully pressed.

The power switch is turned on (the photographing mode is set)
When the start process is started, first, the lens side control circuit 70 initializes the internal RAM and the like, and
1, M2, M3 are driven to open the aperture blade 53 to the origin position (open position), and the second lens unit L2 and the third lens unit L3 are moved to the origin position, and the motors M1, M2, M
3 is stopped at the detent position (one-phase excitation position) (S
101). Next, the CCD driver 77 is started and the CCD driver 77 is started.
The imaging operation by the imaging element 18 is started (S10
2). Once activated, the CCD driver 77 of this embodiment is configured to repeat the imaging process until a process such as receiving a stop process or turning off the power is performed.

Next, it is checked whether or not the release switch 72 is half-pressed. If it is not half-pressed, that is, if the photographing is not performed, the processing from S104 is executed (S104).
103: YES, S104-S113, S129), if the release switch 72 is half-pressed, the photographing is performed.
The processing from step 114 is executed (S103: YES, S114)
S125, S129), and the release switch 72
If is pressed completely, a writing process of writing the image data to the image data recording device 76 is executed (S125:
YES, S127, S129).

[Normal Driving Operation (Operations Other Than Shooting)] The processing when the release switch 72 is not half-pressed is as follows. First, “0” is set to a shooting flag for identifying whether or not shooting is performed (S104). When "0" is set in the shooting flag, each table 2
Is selected, and the number of drive pulses of the pulse motors M1 and M2 is set as an even number. Next, the photometer 73 is operated to perform photometry (S105). Based on the measured value, the aperture value at which an appropriate exposure amount is obtained is determined by the number of drive pulses (even number) of the aperture pulse motor M1 from the aperture origin position. ) (S
107).

Then, the absolute position of the third lens unit L3 is detected via the third-group volume 40 (S109), and the distance measuring device 74 is operated to measure the distance (S111). Based on the position information of the group L3, the position of the second lens group L2 is set as the number of drive pulses (even number) for driving the second group pulse motor M2 from the origin position (S11).
3). Then, S104 to S1 until the power is turned off.
13 is repeated (S129: NO, S103 to S1)
13, S129).

[High-precision operation (operation during photographing)] The processing when the release switch 72 is half-pressed is as follows. First, "1" is set to a shooting flag for identifying whether or not shooting is performed (S114). When "1" is set in the photographing flag, each table 2 is selected, and the number of drive pulses of the pulse motors M1 and M2 is set to an integer without being an even number, thereby enabling drive at one step angle.

Next, the photometer 73 is operated to perform photometry (S115). Based on the measured value, the aperture value at which an appropriate exposure is obtained is determined by the drive pulse of the aperture pulse motor M1 from the aperture origin position. It is set as a number (an integer including an even number and an odd number) (S117). And 3rd group volume 4
0, the absolute position of the third lens unit L3 is detected (S1
19), the distance measuring device 74 is operated to measure the distance (S12).
1) The position of the second lens unit L2 is set as the number of drive pulses (an integer including an even number and an odd number) for driving the second group pulse motor M2 from the origin position based on the distance measurement value and the position information of the third lens unit L3. It is set (S123). Then, it is checked whether the release switch 72 is fully pressed,
If it is fully pressed, the image data captured by the CCD image sensor 18 is written to the image data recording device 76 (S125: YES, S127). If it is not fully pressed, it is not written (S125: NO). Until is turned off, the processing of S114 to S127 is repeated.

When the power is turned off, an end process is executed and the operation is stopped (S129: YES, S131). The end processing includes at least power-off processing and stop processing of the CCD driver 77, but may also include origin movement processing of the motors M1, M2, and M3.

While the above process is repeated, the motors M1 and M2 are driven by a timer interrupt. An outline of the processing will be described with reference to the flowcharts shown in FIGS.

[Normal Drive] First, the timer interrupt operation during normal drive will be described. In the normal drive, “0” is set in the shooting flag, and the M1 set value and the M2 set value, which are the number of drive pulses of the motors M1 and M2, are set as even numbers. The current values of M1 and M2 are the pulse motor M
1, M2 means the number of pulses driven from the origin position.
The pulse motors M1 and M2 count the first two-phase excitation as one pulse or one step angle with the detent position as the initial position.

When the timer interrupt is entered, since the photographing flag is "0", it is checked whether the current value of M1 (the number of pulses for driving the aperture pulse motor M1) is an even number (S).
201; YES, S203). If it is an odd number, it is excited by +1 step (one step driving in the forward direction), the current value of M1 is incremented by 1, the excitation of the pulse motor M1 is turned off, and the process proceeds to S211 (S203; NO, S205,
S207, S209, S211). In other words, when the current value of M1 is an odd number, it is a two-phase excitation position, so that one-phase excitation is performed to rotate to the detent position, and the excitation is turned off.
On the other hand, if the M1 current value is an even number, the pulse motor M
Since 1 is stopped at the detent position, S205 to S
Skip 209 and proceed to S211. By the above processing, during normal operation, the process always proceeds to S211 with the excitation turned off at the detent position.

In S211, it is checked whether the current M1 value is equal to the M1 set value. If it is smaller, the diaphragm pulse motor M1 is excited by +1 step and the current value of M1 is set to 1
Increment (S211: NO, S213: YES, S
215, S217), if larger, pulse motor M for aperture
Excitation of 1 for -1 step (drive for 1 step in reverse direction)
And decrement the M1 current value by 1 (S211: NO,
S213: NO, S219: YES, S221, S22
3). Then, it is checked whether or not the current value of M1 is even. If it is even, the excitation of the aperture pulse motor M1 is turned off because it is a detent position, and if it is odd, the excitation is in a two-phase excitation position and the process proceeds to the motor M2 without turning off the excitation (S22).
9, S231). In other words, the aperture pulse motor M1 is M
When the current value is at a detent position where the current value is an even number, the excitation is turned off.

When the M1 current value becomes equal to the M1 set value, that is, since the aperture pulse motor M1 is at an even-numbered detent position, the aperture pulse motor M1
(S211: YE)
S, S227, S229: YES, S231). As described above, during normal operation, the aperture pulse motor M1 is set to S20.
In steps S209 to S209, even-number step driving, that is, driving to the detent position, is performed, and S213 to S217 or S21 is performed.
In the processing from 9 to S223, the odd-numbered step drive, that is, the drive to the equilibrium position between the detent positions is performed.

The second group pulse motor M2 is also driven in the same manner as the stop pulse motor M1. That is, when the motor M2 process is started, it is checked whether or not the current value of M2 (the number of pulses driving the second group pulse motor M2) is an even number because the shooting flag is "0"(S301; YES, S303). If it is an odd number, it is excited by +1 step (drive one step forward)
Then, the current value of M2 is incremented by 1, the excitation of the second group pulse motor M2 is turned off, and the process proceeds to S311 (S303; NO,
S305, S307, S309, S311). That is,
When the current value of M2 is an odd number, it is a two-phase excitation position,
The phase is excited to rotate to the detent position, and the excitation is turned off. On the other hand, if the current value of M2 is an even number, the pulse motor M2 for the second group is stopped at the detent position.
The process skips 305 to S309 and proceeds to S311. By the above processing, during normal operation, the process always proceeds to S311 with the excitation turned off at the detent position.

In S311, it is checked whether the current M2 value is equal to the M2 set value. If it is smaller, the second group pulse motor M2 is excited by +1 step (one step driving in the forward direction) and the current value of M2 is incremented by 1 (S31).
1: NO, S313: YES, S315, S317), if it is larger, the second group pulse motor M2 is excited by -1 step (driven by one step in the reverse direction) and the current value of M2 is decremented by 1 (S311: NO, S313). : NO, S319: YE
S: S321, S323). Then, it is checked whether or not the M2 current value is an even number. If it is an even number, the excitation of the second group pulse motor M2 is turned off because it is a detent position, and if it is an odd number, the excitation is turned off since it is a two-phase excitation position (S329, S331). That is, the second group pulse motor M
When 2 is in the detent position where the current value of M2 is even, the excitation is always cut off.

When the M2 current value becomes equal to the M2 set value, that is, since the second group pulse motor M2 is at an even-numbered detent position, the second group pulse motor M2 is excited and returns (S311: YES, S327,
S329: YES, S331). As described above, in the normal operation, the second group pulse motor M2 is driven to the even-numbered step, that is, the detent position in the processing of S303 to S309, and is driven to the odd-numbered step, that is, the detent position in the processing of S313 to S317 or S319 to S323. It drives to an equilibrium position between the detent position.

As described above, in the normal driving operation other than the photographing operation, the motors M1 and M2 are driven in even-numbered steps, and are always stopped at the even-numbered steps at the detent position to stop the excitation. Stop position control is now possible.

Next, a description will be given of a high-precision driving operation at the time of photographing. The high-precision driving operation of this embodiment is performed by the motors M1 and M
2 is driven in units of one step angle, excitation is maintained and stopped at a stable position (odd step position) which is not a detent position, and after photographing is completed, the excitation is returned to the detent position (even step position) to turn off the excitation. Have.

[High Accuracy Driving] Next, high accuracy driving processing will be described. In the high-precision driving process, the shooting flag is set to “1” in S114, and an odd value may be set to the M1 and M2 set values that are the number of pulses for driving the motors M1 and M2. It is different from the driving process.

When the timer interrupt process starts, since the shooting flag is "1", it is immediately checked whether the current M1 value is equal to the M1 set value (S201: YES, S21).
1). The processing when the M1 current value is not equal to the M1 set value is the same as that in the normal driving processing.

When the current M1 value becomes equal to the M1 set value, the photographing flag is 1, so that the excitation cutting process in S227 is skipped and it is checked whether the current M1 value is an even number (S211: YES, S225: NO, S229). When the current value of M1 is an even number, since the aperture pulse motor M1 is at the detent position, the excitation of the aperture pulse motor M1 is turned off and the process proceeds to the motor M2 (S229: YES, S23).
1). However, when the current value of M1 is an odd number, the pulse motor M1 is not at the detent position, so that the excitation of the pulse motor M1 is not turned off, that is, the two-phase excitation is maintained. By this processing, the aperture pulse motor M1, that is, the aperture blade 53 is placed in an odd step position (two-phase excitation position).
And an appropriate amount of received light can be given by the CCD image pickup device 18.

The second group pulse motor M2 is also driven in the same manner as the stop pulse motor M1. That is, when the motor M2 process is started, since the shooting flag is "1", it is immediately checked whether the current M2 value is equal to the M2 set value (S30).
1: YES, S311). The processing when the M2 current value is not equal to the M2 set value is the same as that in the normal driving processing.

When the current value of M2 is equal to the set value of M2, since the photographing flag is 1, the excitation disconnection processing of S327 is skipped, and it is checked whether the current value of M1 is even (S311: YES, S325: NO, S329). When the current value of M1 is an even number, the second group pulse motor M2 is in the detent position, so that the second group pulse motor M2 is excited and returns (S329: YES, S331). But,
When the current value of M1 is an odd number, the second group pulse motor M2 is not at the detent position, so the excitation of the second group pulse motor M21 is not turned off, that is, the two-phase excitation is maintained. By this processing, the second group pulse motor M2, that is, the second lens group L
2 is held at an odd step position (two-phase excitation position), and C
A clear focused subject image can be formed by the CD imaging device 18.

[Returning process after stopping at odd-numbered position by high-precision driving]
203 to S209, S303 to S in motor 2 processing
In the process 309, the pulse motors M1 and M2 are moved to the odd-numbered step positions (2
After stopping at the phase excitation position, the equilibrium position, and the non-detent position), when the release switch 72 is turned off, the pulse motors M1 and M2 are turned to the even-numbered step positions (one-phase excitation position,
(Detent position).

When the release switch 72 is turned off, S
In step 104, “0” is set in the shooting flag, and in step S107,
In S113, the M1 set value and the M2 set value are set to even numbers. Therefore, when the timer interrupt process is started, S201 to S203 and S301 to S3
Go to 03. Here, if the current value of M1 is not an even number (if it is an odd number), that is, if the stop pulse motor M1 is stopped at an odd step position (two-phase excitation position, non-detent position), the stop pulse motor The motor M1 is two-phase excited. Then, the aperture pulse motor M1 is driven one step forward to rotate to the detent position,
The excitation is turned off after incrementing the current value by one (S2
01: YES, S203: NO, S205, S207, S2
09).

Similarly, if the current value of M2 is not an even number (if it is an odd number), that is, if the second group pulse motor M2 is stopped at an odd step position (two-phase excitation position, non-detent position), The two-group pulse motor M2 is excited in two phases. Therefore, the second group pulse motor M2 is moved forward by 1
Step drive to rotate to detent position, M2 current value is incremented by 1, then excitation is cut off (S301:
YES, S303: NO, S305, S307, S30
9).

By the above processing, it is possible to drive with even more accurate odd-numbered pulses at the time of photographing, and to return to an even-pulse position where excitation is unnecessary when the photographing is completed, thereby turning off the excitation, thereby reducing power consumption. Is now possible.

When the zoom switch 71 is turned on while repeating the above processing, the lens side control circuit 70 executes an interrupt processing to drive the motors M2 and M3 by two steps. The motor driving operation during zooming will be described. In the telephoto end state shown in FIG. 5, when the zoom switch 71 is turned on in the wide direction, the lens side control circuit 70 is interrupted by the second group pulse motor M
The second group frame 16 (the second lens group L2) is driven forward by the two-step angle unit, and the third group motor 17 is driven forward by the two-step angle unit (even number step) by the third group frame 17 (the third lens unit). The group L3) is moved backward. Lens side control circuit 70
Means that every time the motors M2 and M3 are driven by two step angles, M
The 2 current value and the M3 current value are decremented by 2. When the zoom switch 71 is turned off, that is, when the stop signal is received, the lens-side control circuit 70 stops the motors M2 and M3. However, since the current values of M2 and M3 are even numbers, that is, the detent positions of the one-phase excitation, the lens-side control circuit 70 performs excitation. Cut and stop.

On the other hand, when the zoom switch is turned on in the telephoto direction, the lens side control circuit 70 is interrupted by
By driving the second group pulse motor M2 in units of one step angle,
The second group frame 16 (second lens group L2) is moved backward,
By driving the group motor M3 in units of two step angles, the third group frame 17
(The third lens unit L3) is moved forward. The lens-side control circuit 70 increments the M2 current value and the M3 current value by 2 each time the motors M2 and M3 are driven by two step angles. When the lens side control circuit 70 reaches the telephoto end or when the zoom switch 71 is turned off, that is, when the stop signal is received, the motors M2 and M3 are turned on when the current values of M2 and M3 are even numbers, that is, when the one-phase excitation Turn off the excitation at the detent position and stop.

Since the position of the third lens group L3 can be detected by the third group volume 40, the number of drive pulses of the third group pulse motor M3 does not have to be counted.

Based on the focal length set by the above-described zooming process, the lens side control circuit 70 drives the stop pulse motor M1 and the second group pulse motor M2 with high precision. The number of drive pulses of the aperture pulse motor M1 is set based on the subject luminance information from the photometric device 73,
Based on the number of driving pulses, the aperture blade motor 5 is driven from the aperture origin position (detection position by the aperture origin sensor 55) to the set aperture value to set the aperture blade 5
3 is set. Further, the number of drive pulses of the second group pulse motor M2 is set based on the set focal length information and the subject distance information by the distance measuring device 74, and based on this number of drive pulses, the second group lens origin position (the second group origin) The second lens group L2 moves along the optical axis while being controlled in position by the second group pulse motor M2 driven from the (detection position by the sensor 22), and focuses. That is, when the position (focal length) of the third lens unit L3 is determined by the zoom switch 71, the position of the second lens unit L2 is uniquely determined by the set focal length and the subject distance information by the distance measuring device 74. By the above operation of moving the second lens unit L2 to the determined in-focus position, an in-focus subject image is formed on the CCD image sensor 18.

When the release switch 72 is pressed halfway, the photometric device 73 and the distance measuring device 74 operate normally, and when the release switch 72 is fully pressed, high accuracy operation is achieved. Wear can be reduced.

As described above, in the present embodiment, the 1-2-phase excitation pulse motors M1, M2, and M3 are driven in even-numbered steps except when photographing, and when they are stopped, the excitation is always cut off at the detent position. Wear can be reduced. At the time of photographing, the pulse motors M1 and M2 are set to 1
Since the step driving is performed, it is possible to capture an image with a more accurate light receiving amount and focus. Therefore, especially when applied to a digital still camera equipped with a liquid crystal display, by driving normally when observing a subject, it is possible to reduce power consumption while obtaining an image quality that does not hinder observation on the liquid crystal display,
By performing high-precision driving at the time of shooting, that is, when writing captured image data to the memory, it is possible to obtain high-quality image data with accurate focus and a more appropriate amount of received light.

In the illustrated embodiment, the on / off state of the release switch 71 is directly detected by the lens side control circuit 70. However, when the zoom lens unit and the camera unit are provided separately and independently, the release switch is used. The on / off state of 71 is detected by the camera body side control circuit, and a release switch on signal is received by communication between the lens side control circuit and the camera body side control circuit.
Is replaced with a determination as to whether or not this signal has been received. Alternatively, the configuration is such that the photographing flag is received by communication from the camera body side control circuit.

The embodiment of the present invention applied to a digital camera equipped with three 1-2-phase excitation pulse motors has been described above. However, the present invention is not limited to this embodiment, and is not limited to this embodiment. The present invention can be applied to any camera provided with a pulse motor. Further, in the illustrated embodiment, the zoom lens unit having the photographing lens and the camera body unit having the image data storage unit are formed separately, but the present invention is applied to a digital still camera in which these are integrated. You can also.

[0065]

As is apparent from the above description, according to the present invention, the camera is equipped with a 1-2-phase excitation type pulse motor, and is stopped in units of one step angle in high-precision operation.
During normal operation where high precision is not required, the drive is performed in even-numbered step angle units, the excitation is stopped at the detent position, and the excitation is cut off. Therefore, it is possible to reduce the battery consumption while enabling high precision drive. If this pulse motor is used for focus adjustment, it is possible to reduce the power consumption while enabling highly accurate focus adjustment.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of an embodiment of a digital still camera to which the present invention is applied.

FIG. 2 is a left side view of a cross section of a case showing one embodiment of a zoom lens unit according to the present invention.

FIG. 3 is a right side view of the same.

FIG. 4 is a front view of the same.

FIG. 5 is a partially longitudinal left side view showing a telephoto end of the lens unit before the lens drive unit is incorporated.

FIG. 6 is a flowchart showing an outline of an embodiment of a basic operation of the digital still camera to which the present invention is applied.

FIG. 7 is a diagram showing, in a flowchart, one embodiment of a pulse motor driving process in the digital still camera.

FIG. 8 is a flowchart showing one embodiment of a pulse motor driving process in the digital still camera.

[Description of Signs] L1 First lens group L2 Second lens group L3 Third lens group M1 Aperture pulse motor M2 Second group pulse motor M3 Third group pulse motor 10 Lens barrel 11 Casing 12 Front plastic body 13 Rear plastic body 14 Aperture block 16 2nd group frame 17 3rd group frame 18 CCD image sensor 22 2nd group origin sensor (lens initial position detecting means) 26 27 28 Motor driver 30 Lens drive unit 40 Volume for 3rd group (variable resistor) 53 Aperture blade 55 Aperture Origin sensor (aperture initial position detection means) 70 Lens side control circuit (drive control means, calculation means) 71 Zoom switch 72 Release switch 73 Photometry device 74 Distance measurement device 75 Signal processing circuit 76 Image data storage device 77 CCD driver

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Sato 2-36-9 Maenocho, Itabashi-ku, Tokyo Inside Asahiko Gaku Kogyo Co., Ltd. (72) Inventor Yuki Shiba 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Gaku Kogyo Co., Ltd. (72) Inventor Tatsuya Yoshida 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Nobuyuki Nagai 2-36-9, Maeno-cho, Itabashi-ku, Tokyo No Asahi Gaku Kogyo Co., Ltd.

Claims (8)

[Claims] 1. A drive device for driving and stopping a 1-2-phase excitation type pulse motor mounted on a camera by a 1-2-phase excitation. When the pulse motor is driven with high precision, When the motor is stopped at the one-phase excitation position, the excitation is stopped at the one-phase excitation position and stopped. When the motor is stopped at the two-phase excitation position, the excitation is maintained and stopped. A pulse motor drive device for a camera, comprising: a drive control means for always stopping and stopping excitation at a one-phase excitation position. 2. A driving device for driving a 1-2-phase excitation type pulse motor mounted on a camera by a 1-2-phase excitation in response to a drive signal and stopping in response to a stop signal. When the motor is driven with high accuracy, when the stop signal is received at the one-phase excitation position, the excitation is stopped at the one-phase excitation position, and when the stop signal is received at the two-phase excitation position, the two-phase excitation is maintained. When the pulse motor is normally driven, when the stop signal is received at the one-phase excitation position, the excitation is stopped at the one-phase excitation position, and when the stop signal is received at the two-phase excitation position, one more phase is received. A pulse motor driving device for a camera, comprising: drive control means for exciting and then stopping the excitation at the one-phase excitation position to stop the excitation. 3. The pulse motor driving device for a camera according to claim 1, wherein the pulse motor is a pulse motor for moving a focusing lens of a photographing lens, and the drive control unit is configured to control the driving of the camera during photographing. A pulse motor driving device for a camera, wherein the driving is performed with high precision and the normal driving is performed except during photographing. 4. A pulse motor driving device for a camera according to claim 1, wherein said pulse motor is a pulse motor for driving an aperture of a photographic lens to open and close, and said drive control means is configured to control said high level during photographing. A pulse motor driving device for a camera, wherein the driving is performed with accuracy and the normal driving is performed except during photographing. 5. The pulse motor drive device for a camera according to claim 3, wherein the drive control means stops the pulse motor at a two-phase excitation position while maintaining the two-phase excitation state during the photographing. A pulse motor driving device for a camera, wherein when the photographing is completed, the pulse motor is excited by one phase after the photographing is completed, and then the excitation is stopped at the one-phase excitation position and stopped. 6. The pulse motor driving device for a camera according to claim 3, further comprising a calculating means for calculating the number of driving pulses for driving the pulse motor, wherein the calculating means calculates the number of driving pulses during photographing. A pulse motor driving device for a camera, wherein the number of driving pulses is set to an even number except when photographing is performed. 7. A pulse motor driving device for a camera according to claim 1, further comprising: a digital still camera including a CCD imaging device and a memory unit for storing image data captured by the CCD imaging device. A pulse motor driving device for a camera, wherein image data picked up by a CCD image pickup device is recorded in the memory means during the photographing. 8. A pulse motor driving device for a camera according to claim 1, wherein the image pickup device includes a CCD image pickup device, a memory unit for storing image data picked up by the CCD image pickup device, and a display device for displaying the image data. The drive control unit is driven with high precision when recording the image data in the memory unit, and displays the image data on the liquid crystal display. A pulse motor driving device for a camera, wherein the normal driving is performed when recording is not performed.