JPH08327877A - Pulse motor control method for camera provided with lens standby position - Google Patents

Abstract

PURPOSE: To provide a control method for pulse motor of a camera provided with a lens standby position shortening a lens extension time and a lens returning time by providing the control reference and the lens standby position, extending a lens from the lens standby position and returning it to the standby position. CONSTITUTION: A number of lens extension steps and a number of accelerating/ decelerating steps are compared and a pulse motor 22 is controlled at a rate corresponding to a number of extension steps. The sum of a number of steps of the lens standby position equivalent to a number of lens returning steps and a number of extension steps is compared with the number of accelerating/ decelerating steps and the pulse motor 22 is controlled at a rate corresponding to a number of returning steps. At the time of driving the lens standby position, a quotient and a remainder are found by dividing a number of steps of the lens standby position by a number of driving pulse data, after detecting a reference signal, the pulse motor is driven by means of the driving pulse data with a number of times equivalent to the quotient and with a number of pulses equivalent to the remainder and stopped at an arbitrary lens standby position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor control method for a camera which electrically detects a reference signal of a pulse motor to drive a lens and which is provided with a lens standby position.

[0002]

2. Description of the Related Art In recent years, a pulse motor is used to extend a photographing lens to a focus position, and there is a camera in which one pulse motor is used to drive a photographing lens and to open / close a shutter. The invention described in Japanese Patent Application Laid-Open No. 5-232543 filed by the applicant of the present application is an example in which the photographing lens drive and the shutter opening / closing drive are performed by one pulse motor, and the basic reciprocating member is used as the home position by the pulse motor. The basic reciprocating member is driven to rotate in the forward and reverse directions, and when the basic reciprocating member is normally rotated from the home position, the lens advancing member is normally rotated through the ratchet substrate. At this time, the lens holding frame is moved to the distance measuring position by the cam action. Then, after the basic reciprocating member is rotated backward from the home position, the ratchet board is passed through the home position with the ratchet substrate left in that position. The shutter lever is opened by rotating the open / close lever.

The invention of the above publication also provides photoelectric detection means for increasing the pulse width while releasing the member (ratchet) for holding the lens extension position, or for detecting a predetermined vicinity position set near the control reference position. The technical idea is to reset the pulse motor from the position where the output signal of the photoelectric detection means has changed to a reference position by performing a predetermined control and stopping the pulse motor. Furthermore, in order to eliminate the effects of mechanical errors related to the shooting lens extension operation, this mechanical error is converted into the number of drive pulses applied to the pulse motor, and this is stored as a unique adjustment value for each camera. It also has a technical idea of storing in the means and performing the electric control by adding the above-mentioned unique adjustment value to the control value at the time of electric control when the photographing lens is extended to the focusing position.

[0004]

The present invention is an improvement of the invention described in the above publication. That is, one object of the present invention is to provide a lens standby position in addition to the control reference, and to extend the lens from this lens standby position and to return the lens from the lens extension position to the standby position, thereby providing a lens extension time, Another object of the present invention is to provide a pulse motor control method for a camera provided with a lens standby position that makes it possible to shorten the lens return time.

Another object of the present invention is to allow the lens standby position to be arbitrarily set, thereby reducing the amount of extension of the taking lens and reducing the time lag until the shutter operation. It is to provide a method for controlling a pulse motor of a camera provided with a position.

Still another object of the present invention is to provide a pulse motor control method for a camera provided with a lens standby position which can prevent erroneous detection and variations of the reference signal.

Still another object of the present invention is to provide a device for storing the focus adjustment amount from the reference signal output position of the pulse motor. Depending on the focus adjustment amount from the reference signal, it may take time to extend the lens during photographing. Therefore, by setting the lens standby position as an adjustment value before moving out the taking lens, the lens moving out amount at the time of shooting can be reduced accordingly, the lens moving out time can be reduced, and the time lag until the shutter operation can be reduced. An object of the present invention is to provide a pulse motor control method for a camera provided with a standby position.

Still another object of the present invention is to provide the following by driving to the lens standby position after the reset operation and the lens return in the one in which the lens standby position is set as the adjustment value before the taking out of the taking lens as described above. It is an object of the present invention to provide a pulse motor control method for a camera provided with a lens standby position that is prepared for a release and that can reduce the time lag until the shutter is operated in the next release.

[0009]

In order to achieve the above-mentioned object, the invention according to claim 1 compares the number of feeding steps and the number of acceleration / deceleration steps at the time of lens feeding, and a pulse corresponding to the number of feeding steps. The pulse motor is controlled at a rate. According to the second aspect of the present invention, when the lens is returned, the sum of the lens standby position step number corresponding to the lens return step number and the feeding step number is compared with the acceleration / deceleration step number, and the pulse corresponding to the return step number is compared. The pulse motor may be controlled at a rate.

According to a third aspect of the present invention, when the lens standby position is driven, the lens standby position step number is divided by the drive pulse data number to obtain the quotient and the remainder, and after the reference signal is detected, the quotient is obtained using the drive pulse data. By driving the pulse motor a corresponding number of times and driving the pulse motor with the number of pulses corresponding to the above-mentioned surplus, it is possible to stop at an arbitrary lens standby position.

According to a fourth aspect of the invention, the reference signal detection of the pulse motor can be selected when the lens is extended or when the lens is returned.

According to a fifth aspect of the present invention, the focus adjustment amount from the reference signal of the pulse motor is stored, and the lens standby position is set as the adjustment value before the taking lens is extended in accordance with the focus adjustment amount, and the lens standby position is set. The lens is driven to the position. As in the invention described in claim 6, the lens may be driven to the lens standby position after the reset operation or the lens return.

[0013]

According to the first aspect of the present invention, the number of feeding steps is compared with the number of acceleration / deceleration steps when the lens is fed, and if the number of feeding steps is close to the number of acceleration / deceleration steps, the pulse motor is controlled at a low pulse rate at a low speed. If the number of feeding steps is considerably larger than the number of acceleration / deceleration steps, the pulse motor is controlled at high speed with a high pulse rate. According to the second aspect of the invention, when the lens is returned, the sum of the lens standby position step number corresponding to the lens return step number and the feeding step number is compared with the acceleration / deceleration step number, and the lens return step number is the acceleration / deceleration step number. The pulse motor is controlled at a low pulse rate at a low speed when the value is close to, and the pulse motor is controlled at a high speed at a high pulse rate when the lens return step number is considerably larger than the acceleration / deceleration step number.

According to the third aspect of the present invention, when the lens standby position is driven, the lens standby position step number is divided by the drive pulse data number to obtain the quotient and the remainder, and after the reference signal is detected, the quotient is obtained by the drive pulse data. By driving the pulse motor a corresponding number of times and driving the pulse motor with the number of pulses corresponding to the above-mentioned surplus, the lens can be accurately moved to a predetermined lens standby position and made to stand by. The number of steps in the lens standby position may be set arbitrarily, whereby the lens can be stopped at any standby position.

According to the fourth aspect of the invention, the reference signal of the pulse motor is selected so as to be detected either when the lens is extended or when the lens is returned. When the reference signal is detected when the lens is extended and when the reference signal is detected when the lens is returned, the output timing of the reference signal may deviate due to hysteresis of the sensor or rattling of mechanical components. By selecting to detect either when the lens is extended or when the lens is returned,
There is no deviation in the output timing of the reference signal.

According to the fifth aspect of the present invention, the lens standby position is set as an adjustment value before the photographic lens is extended according to the focus adjustment amount, and the lens is driven to this lens standby position. Therefore, the lens is extended from the lens standby position. The lens extension amount at the time of minute photographing is reduced, the lens extension time is reduced, and the time lag until the shutter operation is reduced.

According to the sixth aspect of the invention, since the lens is driven to the lens standby position after the reset operation or after the lens is returned to prepare for the next release, the time lag until the shutter operation is reduced in the next release.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pulse motor control method for a camera having a lens standby position according to the present invention will be described below with reference to the drawings. FIG. 1 shows an electrical component block of a circuit used in an embodiment of the present invention, mainly a CPU.
1 and interface (hereinafter referred to as "IF") IC20
It consists of. From CPU 2 to DC-
A constant voltage power supply is supplied via the DC converter 3. The CPU 1 has a reset IC 4, a remote control IC 5, an AEIC 6 for inputting photometry data, an AFIC 7 for inputting distance measurement data, a date imprinting LED 8, a clock oscillator 9, a strobe light emitter 11, an external liquid crystal display element (hereinafter, the liquid crystal display element is "LCD") 12, operation switch 13 linked to the release button, finder display LCD 1
No. 4 driver 15, EEPRO for storing various adjustment values, etc.
M16, a personal computer 10 used for adjustment and inspection is connected.

The IFIC 20 controls the constant voltage control transistor 24 to control its constant voltage output. IFI
C20 is a pulse motor 22 for driving a focusing lens or the like.
The constant voltage driver 21, the display LED 23, the driver 31 of the zoom motor 32 and the film feeding motor 33, the driver 34 of the shutter 35, the driver 36 of the lamp 37 for performing various self-timer operations and other various operations, the shutter operation and other operations of each part. A photoreflector (PR) and a photointerrupter (PI) 38 for detecting, a film sensitivity, and a DX switch 39 for detecting various data relating to the film from the contacts of the film cartridge are connected.

When reset by the reset IC 4, the CPU 1 activates the DC-DC converter 3 and supplies a constant voltage of, for example, 5V to each IC. Each IC has a built-in power save function that consumes less current except when operating. The IFIC 20 is controlled by serial communication data from the CPU 1. When the CPU 1 periodically detects the operation of the operation switch 13 and determines that the release button has been pressed, the CPU 1 sends the photometric data to the A
Distance measurement data is fetched from FIC7 and strobe light emitter 1
Checking the charging voltage of 1 and performing a predetermined display by the external LCD 12, the finder LCD 14, and the display LED 23,
After driving the pulse motor 22 to extend the focusing lens to a predetermined position obtained from the distance measurement data, shutter opening / closing control is performed.

In the shutter opening / closing control, the IFIC 20 controls the operation of the constant voltage control transistor 24 based on the serial communication data from the CPU 1 to set the shutter drive voltage, and detects the reflected light from the shutter. Of a reflector (hereinafter referred to as "P
R ") signal. During shutter control, if the subject brightness is low, the strobe 11 emits light in accordance with the shutter operation. Strobe light emission is controlled by flashmatic control, guide number control, or the like so as to achieve proper exposure.

In FIG. 1, a part of the IFIC 20, a part including the constant voltage control transistor 24, and the constant voltage driver 21 constitutes a voltage setting part 40. A specific example of this voltage setting unit 40 is shown in FIG. In FIG. 2, the pulse motor 22 drives the focus lens. The shutter is driven by an electromagnetic plunger or the like (not shown). The output of the constant voltage control transistor 24 is supplied to the pulse motor 22 via the constant voltage driver 21. IFIC20
A control signal is output from the VCONT terminal to control the constant voltage control transistor 24 so that the output voltage of the constant voltage control transistor 24 input to the VSENS terminal matches the set voltage of the CPU 1. FP of IFIC20
The MV terminal is a terminal for outputting the output voltage switching signal of the constant voltage driver 21, and when it is “L”, the constant voltage driver 21 is made to function and is a constant voltage obtained by dividing the reference voltage by the ratio of the resistors R1 and R2. When the pulse motor 22 is driven and is “H”, the constant voltage driver 21 does not function and the constant voltage output of the constant voltage control transistor 24 is used to output the pulse motor 2
Drive 2

The FPM0 to FPM3 terminals of the IFIC 20 are pulse control output terminals for driving and controlling the pulse motor 22. FIG. 3 shows a logical value of the constant voltage driver 21 when the pulse motor 22 is driven by two-phase excitation. The data transmitted from the CPU1 to the IFIC20 is
The IFIC 20 is one of the four data 0Ah, 06h, 09h, 05h shown in FIG. 3, and the IFIC 20 corresponds to the above-mentioned data transmitted from the CPU 1 and the FPM0 to FP.
A pulse control signal is output from the M3 terminal to the constant voltage driver 21. The constant voltage driver 21 uses the above FPM0 to FPM.
A drive pulse is input to the pulse motor 22 according to a combination of pulse control signals from the PM3 terminal to control the rotation of the pulse motor 22. The order of drive pulses when the lens is extended is HH, HL, LH, LL, and the order of drive pulses when the lens is returned is HH, LH, LL, H.
It is L.

As described above, the photographing lens is driven by the rotational driving of the pulse motor 22. FIG. 4 shows an example of photographing lens position control, in other words, pulse motor control. In FIG. 4, the lens position (rotational position of the pulse motor 22) is moved to the home position HP and the lens standby position, respectively, and is extended so as to be focused on the subject distance in the range from the closest distance to the infinity. . The lens standby position may be set to any position, but in the example shown in FIG. 4, the lens standby position is set near the lens position for focusing at a close range, and the pulse motor reference position is set between the home position HP and the lens standby position. The signal (PI) is switched. Further, in the example of FIG. 4, the front side of the lens extension range is the closest distance and the front side is the infinite distance, but depending on the lens design, the front side may be the infinite distance and the front side may be the close distance.

The pulse motor reference signal serves as a reference for counting the number of drive pulses in controlling the pulse motor 22 by the drive pulse, and is from "H" to "L" when the photographing lens reaches a predetermined position. , Or from “L” to “H”. The pulse motor 22 is
The position can be controlled by the number of drive pulses,
The position may not match the number of drive pulses due to step out, etc., so the pulse motor reference signal is output every time a series of operations is performed, and the drive pulses are counted from the time when this reference signal is output. It is like this.

In FIG. 4, first, it is assumed that the taking lens is at the lens standby position, and the lens is extended from this standby position to the in-focus position according to the distance measurement data. As shown in FIG. 5, initially, there is an acceleration section in which the pulse motor is driven at a low pulse rate, and there is a lens extension drive section in which the pulse motor is driven at a next higher pulse rate, which is low again when the extension position approaches the target position. There is a deceleration section of the pulse rate, and it stops at the target position, and the shutter is opened and closed at this position. As described above, when the lens standby position is extended to the target position, and because there is a lens extension drive section that is driven at a high pulse rate, the taking lens is rapidly extended, and the time lag until the shutter operation is reduced. To do. Whether to increase or decrease the pulse rate when the lens is extended depends on the comparison between the number of extension steps and the number of acceleration / deceleration steps. When the target position for lens extension is near the lens standby position and the number of extension steps is close to the number of acceleration / deceleration steps, the lens extension is performed at a low pulse rate only in the acceleration section and the deceleration section.

When the opening / closing operation of the shutter is completed, the lens return drive to the home position and the lens standby position drive for moving the lens to the standby position are performed. Figure 4,
As shown in FIG. 5, in the lens return drive, initially, there is a deceleration section in which the pulse motor is driven in the reverse direction at the low pulse rate, and there is a lens return drive section in which the pulse motor is driven at the next higher pulse rate. The lens return section passes through the lens standby position, and when it approaches the home position, there is a deceleration section with a low pulse rate and reaches the home position.
When the home position is reached, the pulse motor is driven again in the forward rotation direction to reach the lens standby position. Driving to this lens standby position also has an acceleration section first, and then a lens standby position drive section with a drive pulse of a higher rate,
After the deceleration section, the lens reaches the lens standby position and stops. The pulse motor reference signal is changed from "H" to "L" within the lens standby position drive section, and the drive pulse is newly counted from this change point.

Further, when the camera is reset, for example, when the lens barrier is retracted from the lens front surface to use the camera from the housed state in which the lens front surface is shielded by the lens barrier, the reset operation is performed. .
The reset operation is, as shown in FIGS. 4 and 6, an operation of returning the lens from the lens standby position to the home position, and then extending it to the lens standby position again. The returning operation from the lens standby position to the home position is performed in the deceleration section by the low-rate drive pulse. The operation from the home position to the lens standby position is performed through an acceleration section, a lens standby position drive section with a high-rate drive pulse, and a deceleration section, in the same manner as the above operation. In this way, at the time of reset, the pulse motor reference signal newly output can be utilized by returning to the home position and then driving to the lens standby position. The deviation between the number of drive pulses and the lens position is corrected every time, and the lens position can be accurately controlled.

The pulse motor reference signal changes between "H" and "L" when the lens passes a predetermined reference position. In the illustrated example, "H" is output when the lens is extended.
To “L”, and when returning the lens, “L” to “H”
Convert to. Which one is used as the reference position signal can be arbitrarily selected. However, since there is a difference in the signal output timing between when the lens is extended and when the lens is returned due to mechanical backlash, the positional relationship of the sensor, hysteresis, etc., either one is selected.

Next, the operation described above will be described with reference to FIGS.
This will be described with reference to the flowchart shown in FIG. The lens return direction is set to FCOUNT_F = 0. At this time, the home position HP is used to perform the reference positioning of the pulse motor, and the lens extension direction is set to FCOUNT_F = 1.
At this time, the description will be given on the assumption that the reference positioning of the pulse motor is performed at the lens standby position.

FIG. 7 shows the operation at the time of resetting the pulse motor. When the CPU 1 is reset, the lens position, that is, the pulse motor rotation position is initialized.
First, interrupts are prohibited in order to accurately output the drive pulse width of the pulse motor. The output of the photo interrupter (hereinafter referred to as “PI”) that is the pulse motor reference signal is “L”
Whether the pulse motor position is closer to the home position than the current pulse motor reference position,
It is detected whether the lens is on the standby position side. If PI = L, it is on the lens standby position side. WOR if PI = H
K_0L = 32 is set, and the reset pulse width is set. This WORK_0L is a pulse count RAM, and WORK_0L = 32 means that the pulse motor drive NG flag (PMNG_B) determination pulse number when PI does not change even if the pulse motor is driven is set to "32". I mean. Therefore, if PI does not become 0 even if the output pulse is output 32 times, PMN
The pulse motor drive NG flag is set with G_B = 1.

In FIG. 7, "reset pulse width setting"
Is for setting the pulse motor drive pulse width when the lens position is initially set. When PI = L from the beginning or when PI changes from “L” to “H”, WOR
K_0L = FFH (for example, 255) is set, the reset pulse width is set, and then the return pulse is output. If PI is changed from "L" to "H" by this return pulse output, pulse motor home position drive RDHP_S
And then drive PRE_S from the pulse motor home position to the lens standby position to complete the lens position initialization. Even if PI does not switch to “H” after conversion to “L”, PMNG_B = 1 is set and the pulse motor drive NG flag is set.

FIG. 8 shows the operation of the pulse motor home position drive RDHP_S. FCOUNT_F is PI
1 is a flag indicating the reference direction of the signal. When 0, “L” to “H”, that is, the lens returning direction, and when 1 is “H” to “L”, that is, the lens moving direction. It is set in the EEPROM 16 shown, and after adjustment, it is fixed to either one and lens control is performed. FCOU
When NT_F = 0, RDHPPM = PMDD and pulse motor drive data PMDD when the PI signal changes from “L” to “H” is stored. After that, a return pulse is output to drive the pulse motor toward the home position. And when FCOUNT_F = 0, PMD
The number of times D = PME (PME_COUNT = 3) is counted and set to the home position. PME is EEPR
It is the home position pulse motor drive data stored in the OM.

When FCOUNT_F = 1, the number of drive pulses (PME_COUNT = 10) is output to set the home position. In this way, PME_COUNT
Is the number of times PMDD = PME or the number of drive pulses depending on FCOUNT_F. In FIG. 8, “weight 10 mS is the pulse motor stop stabilization time. In this way, driving to the home position is completed.

9 to 11, the lens is driven to the home position and then to the lens standby position (PRE_
STEP) is shown. Here, the pulse motor control method changes depending on FCOUNT_F. FCOUNT_F =
In the case of 1, the pulse motor is driven to extend the lens until PI = L. Here, as described with reference to FIG. 4, an acceleration section with a predetermined approach pulse width,
Following this, there is a lens standby position drive section with a predetermined extension pulse width. When PI = L, the reference position of the pulse motor at the lens standby position is determined by calculation. Specifically, PRE_STEP / 4 is calculated to obtain the integer part of the quotient and the integer part of the remainder. The reason that the denominator of the above arithmetic expression is 4 is that the number of pulse data is four as HH, HL, LH, and LL as described with reference to FIG. In FIG. 9, “WORK_1L = PME_COU”
“8” of “NT + 8” is a margin value for detecting PI = L. When FCOUNT_F is 0, the PI signal detection is not necessary because the reference position of the pulse motor has already been determined at the home position.

In FIG. 10, the number to be compared with PRE_STEP is changed depending on whether FCOUNT_F is 0 or 1.
That is, when FCOUNT_F = 0, FMRES *
2. If FCOUNT_F = 1, then FMRES.
The difference in the comparison values here is that when FCOUNT_F = 1, the lens advance acceleration has already been completed, and therefore only deceleration is performed. The above FCOUNT_F is determined, and the PRE_STEP number is divided into acceleration / constant speed / deceleration states to set pulses and drive the pulse motor.
P in comparing PRE_STEP and WORK_0L
If RE_STEP is large, accelerate the pulse motor.
The lens is extended to the lens standby position by controlling in order of constant speed drive and deceleration. When PRE_STEP is smaller than WORK_0L, the pulse motor is controlled only by acceleration / deceleration to extend the lens to the lens standby position. The pulse width has a relationship of acceleration = deceleration> constant speed, and if expressed by a pulse rate, the relationship of acceleration = deceleration <constant speed.

If PRE_STEP is greater than WORK_0L and FCOUNT_F = 0, then FIG.
Jump to the lens extension flow chart shown in 2,
The lens is extended to the lens standby position. On the other hand, FC
In the case of OUNT_F = 1, PMDD = PME is driven, the pulse motor is driven a number of times corresponding to the quotient of PRE_STEP / 4 calculated previously, and then the lens is extended by the number of pulses corresponding to the remainder of PRE_STEP / 4 to set the lens standby position. Set to.

Next, the lens extension operation up to the in-focus position will be described with reference to FIGS. In FIG. 12, the number of pulses required to drive from the lens standby position to the in-focus position is FSTEP based on the distance measurement result.
By comparing STEP with FMRES * 2, it is determined whether there are more pulses than required for pulse motor acceleration / deceleration, and FST is applied to each state of acceleration / constant speed / deceleration.
Divide the EP number and set the pulse number. Above FSTE
When P is larger than FMRES * 2, the pulse motor is controlled in the order of acceleration / constant speed / deceleration to extend the lens to FSTEP. If FSTEP is smaller than FMRES * 2, the pulse motor is controlled only by acceleration / deceleration and FSTE
The lens is extended to P. The pulse width has a relationship of acceleration = deceleration> constant speed, and if expressed by a pulse rate, the relationship of acceleration = deceleration <constant speed.

Next, the lens returning operation will be described with reference to FIGS. 14 and 15. Here, FCOUNT_F is 0
1 or FSTEP + PRE_STEP, that is, the number to be compared with the pulse number from the lens return start position to the home position is changed. That is, FCOUNT
When _F = 0, FMRES * 2 + 8. This "8" is the shift amount of the deceleration position, and is for surely detecting the reference signal by decelerating before outputting the pulse motor reference signal. When FCOUNT_F = 1, FMRES * 2. This FMRES * 2 + 8 or F
By comparing MRES * 2 with the acceleration / deceleration step number WORK_0L, it is determined whether there are more pulse numbers than the pulse number required for pulse motor acceleration / deceleration, and further acceleration / deceleration
The number of pulses is set by dividing the number of FSTEP + PRE_STEP into each state of constant speed and deceleration. Above FSTEP + P
If RE_STEP is greater than WORK_0L, the pulse motor is controlled in the order of acceleration / constant speed / deceleration to return the lens toward the home position. FSTEP + PRE
If _STEP is smaller than WORK_0L, the pulse motor is controlled only by acceleration / deceleration to return the lens toward the home position. The pulse width has a relationship of acceleration = deceleration> constant speed, and if expressed by a pulse rate, the relationship of acceleration = deceleration <constant speed.

By driving the lens toward the home position, if PI = H at the pulse motor reference position, drive to the pulse motor home position RDH.
P_S is executed, and then drive PRE_S is further executed from the pulse motor home position to the lens standby position. This places the lens in the standby position, ending the lens return sequence.

Although the embodiments shown in the drawings have been described above, the present invention is not limited to the structures of the embodiments shown in the drawings, and can be arbitrarily designed within the scope not departing from the technical idea described in the claims. You can change it. That is, in the illustrated embodiment, the PRE_STEP position (lens standby position) is set between the pulse motor reference signal output position and the close-range in-focus position, but it may be set to any position depending on various design conditions. It doesn't matter. For example, it may be set between the closest focus position and the infinity focus position, or between the infinity focus position and the pulse motor reference signal output position. Various modifications are conceivable, such as variable according to the shooting result and shooting mode.

Further, in the illustrated embodiment, the pulse motor reference signal output position is set near the in-focus position at the close range, but it may be provided near the in-focus position, or at the close range. It may be provided between the position and the infinity in-focus position.

As is clear from the description of the above embodiment, the pulse motor reference signal is output and the lens is extended from the pulse motor reference signal to the predetermined lens standby position. It is possible to set the lens standby position as an adjustment value and drive the lens to this lens standby position before the shooting lens is extended according to the amount. This makes it possible to reduce the lens extension amount at the time of shooting to reduce the lens extension time, and reduce the time lag until the shutter operation.

[0044]

According to the first aspect of the present invention, when the lens is extended, the number of feeding steps is compared with the number of acceleration / deceleration steps, and the pulse motor is controlled at a pulse rate according to the number of feeding steps. If the number of feeding steps is close to the number of acceleration / deceleration steps, the pulse motor can be controlled at low speed with a low pulse rate, and if the number of feeding steps is considerably larger than the number of acceleration / deceleration steps, the pulse motor can be controlled at high speed with a high pulse rate. Therefore, the lens extension time can be shortened regardless of the lens extension amount.

According to the second aspect of the present invention, when the lens is returned, the sum of the lens standby position step number corresponding to the lens return step number and the feeding step number is compared with the acceleration / deceleration step number to obtain the return step number. Since the pulse motor is controlled at the corresponding pulse rate, if the lens return step count is close to the acceleration / deceleration step count, the pulse motor is controlled at a low pulse rate and the lens return step count is considerably larger than the acceleration / deceleration step count. The pulse motor can be controlled at high speed with a high pulse rate, and the lens return time can be shortened from any lens extension position.

According to the third aspect of the present invention, after the reference signal is detected, the quotient and the remainder obtained by dividing the lens standby position step number by the driving pulse data number are obtained, and the number of pulses corresponding to the quotient in the driving pulse data is counted. Since the motor is driven and the pulse motor is driven with the number of pulses corresponding to the above-mentioned surplus, the lens standby position can be arbitrarily set by arbitrarily setting the number of steps of the lens standby position. It is possible to reduce the lens extension amount and the lens extension time, and to reduce the time lag until the shutter operation.

According to the fourth aspect of the present invention, the reference signal detection of the pulse motor can be selected either when the lens is extended or when the lens is returned. Therefore, the positional relationship between the sensor and the rising edge or the rising edge of the sensor output can be selected. It is only necessary to select a better one in consideration of the positional relationship of the falling edges, and it is possible to prevent erroneous detection and variations in the pulse motor reference signal.

According to the fifth aspect of the present invention, since the lens standby position is set as the adjustment value before the taking-out lens is extended, the moving-out amount of the taking lens is reduced by that amount and the moving-out time is reduced. Therefore, it is possible to reduce the time lag until the shutter is operated.

According to the sixth aspect of the present invention, the lens is driven to the lens standby position after the reset operation and the lens return, so that the lens can be prepared for the next release, and the shutter is operated even in the next release. The time lag can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a pulse motor control method for a camera provided with a lens standby position according to the present invention.

FIG. 2 is a circuit diagram showing a specific example of a voltage setting unit in the above embodiment.

FIG. 3 is a diagram showing logical values of a constant voltage driver in the above embodiment.

FIG. 4 is a diagram showing a lens extension and lens returning operation of the above embodiment.

FIG. 5 is a timing chart showing signals of various parts at the time of release in the above embodiment.

FIG. 6 is a timing chart showing signals of respective parts at the time of resetting in the embodiment.

FIG. 7 is a flowchart showing an operation at the time of resetting in the embodiment.

FIG. 8 is a flowchart showing a home position drive operation of the above embodiment.

FIG. 9 is a flowchart showing the driving operation from the home position to the lens standby position in the above embodiment.

10 is a flowchart showing an operation following the operation of FIG.

11 is a flowchart showing an operation following the operation of FIG.

FIG. 12 is a flowchart showing a lens extension operation of the above embodiment.

FIG. 13 is a flowchart showing an operation that follows the operation of FIG.

FIG. 14 is a flowchart showing a lens returning operation of the above embodiment.

FIG. 15 is a flowchart showing an operation that follows the operation of FIG.

[Explanation of symbols]

 1 CPU 22 Pulse motor

Claims (6)

[Claims] 1. A camera provided with a lens standby position for electrically detecting a reference signal of a pulse motor to drive a lens, compares the number of feeding steps and the number of acceleration / deceleration steps when the lens is extended, and calculates the number of feeding steps. A pulse motor control method comprising controlling a pulse motor at a pulse rate according to the above. 2. A camera having a lens standby position for electrically driving a lens by electrically detecting a reference signal of a pulse motor, and at the time of returning the lens, the lens standby position step number and the extension step number corresponding to the lens return step number. Is compared with the number of acceleration / deceleration steps, and the pulse motor is controlled at a pulse rate according to the number of return steps. 3. A camera provided with a lens standby position for electrically detecting a reference signal of a pulse motor to drive a lens, wherein the lens standby position step number is divided by the number of drive pulse data when the lens standby position is driven. After obtaining the quotient and the remainder, and detecting the reference signal, drive the pulse motor a number of times corresponding to the above quotient with the drive pulse data and drive the pulse motor with the number of pulses corresponding to the above remainder to stop at any lens standby position. A method for controlling a pulse motor. 4. In a camera having a lens standby position for electrically detecting a reference signal of a pulse motor to drive a lens, the reference signal detection of the pulse motor is selected when the lens is extended or when the lens is returned. Possible pulse motor control method. 5. In a camera provided with a lens standby position for electrically detecting a reference signal of a pulse motor to drive a lens, a focus adjustment amount from the reference signal of the pulse motor is stored,
Before extending the taking lens according to this focus adjustment amount,
A pulse motor control method in which the lens standby position is set as an adjustment value and the lens is driven to this lens standby position. 6. A pulse motor control method for driving a lens to a lens standby position after a reset operation and after returning the lens in a camera provided with a lens standby position for electrically driving a lens by electrically detecting a reference signal of the pulse motor. .