JPH09219997A - Step motor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a stepping motor, a step-out of a rotor is accurately detected with a relatively simple configuration regardless of the position of the stepped-out rotor. As a configuration of a step motor, a rotor whose outer peripheral surface is equally divided and is alternately magnetized with different polarities, at least two magnetic pole portions facing the magnetized portion of the rotor, and each magnetic pole portion are provided. At least two coils for exciting the magnetic pole portion, a signal pattern in which a binary signal is recorded at a first duty ratio by being rotated in conjunction with the rotor and equally divided in a circumferential direction, and a second duty ratio. A turntable in which a signal pattern in which a binary signal is recorded and a signal pattern in which a binary signal is recorded at a third duty ratio are arranged in order, and a detection unit that detects information on the turntable are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor used in a lens driving device for a camera.

[0002]

2. Description of the Related Art One in which a camera lens is driven by a step motor is disclosed in, for example, Japanese Patent Laid-Open No. 3-18.
It is known from Japanese Patent No. 0823. An advantage of driving the lens with the step motor is that the lens can be accurately fed according to the number of energizing pulses. However, when the driving load of the lens increases for some reason, the step motor is out of step, and a deviation occurs between the lens feed amount and the number of drive pulses of the step motor. Therefore, a pulse signal is generated according to the rotation of the output shaft of the step motor, and whether or not the step-out occurs depending on whether or not the relationship between the number of pulse signals and the number of drive pulses is a predetermined relationship. There is a way to know that.

As described above, a pulse signal is generated,
The reason why the lens feed-out position is detected in a pseudo manner by detecting it is that it is generally cheaper than the method of detecting the absolute position. In particular,
There is a method of generating a pulse signal by printing light-shielding paint in a radial pattern on a transparent disk and detecting it with a photo interrupter.

[0004]

However, in the above lens drive device, when the step motor out-of-step occurs in the vicinity of the generation of the pulse signal, the rotor of the step motor does not rotate even though the rotor is not rotating. Due to the vibration, a pulse signal may be generated as if the rotor is rotating normally, and there is a drawback that step-out cannot be detected.

Therefore, the first object of the present invention is to make it possible to accurately detect the step-out by a method of detecting a binary signal which is a simple detecting means even if the step-out occurs at any position of the rotor. It is to be.

Secondly, in addition to the above-mentioned object, an object of the present invention is to make it possible to detect whether a step-out has occurred or not by detecting a time interval of a pitch as coarse as possible.

Thirdly, an object of the present invention is to make it possible to accurately detect out-of-step even by a photosensor having no fine pitch resolution.

A fourth object of the present invention is to downsize a device for generating a pulse signal and to accurately detect a step out of a rotor.

[0009]

In order to achieve the above object, the present invention provides a rotor whose outer peripheral surface is equally divided and which is alternately magnetized to have different polarities, and at least facing a magnetized portion of the rotor. Two magnetic pole parts, at least two coils that are provided for each magnetic pole part and excite the magnetic pole parts, are rotated in conjunction with the rotor and are equally divided in the circumferential direction, and a binary signal is generated at the first duty ratio. A turntable in which a recorded signal pattern, a signal pattern in which a binary signal is recorded at a second duty ratio, and a signal pattern in which a binary signal is recorded at a third duty ratio are arranged in order, and the turntable And a detecting means for detecting the information of 1.

In the above structure, the rotating disk and the detecting means can detect the rotation amount and the rotating direction of the rotor, and the pulse generation due to the vibration of the rotor at the time of step-out can be correctly detected as the cause of the step-out. .

In order to achieve the above object, the present invention is directed to a rotor whose outer peripheral surface is divided into 2 · n equal parts and which are alternately magnetized with different polarities, and a magnetized portion of the rotor. At least two magnetic pole parts, at least two coils provided for each magnetic pole part and exciting the magnetic pole parts, rotated in conjunction with the rotor and equally divided in the circumferential direction, and a binary signal with a first duty ratio. And a turntable in which m signal patterns in which binary signals are recorded at a second duty ratio and m signal patterns in which binary signals are recorded at a third duty ratio are arranged in order. And a detecting means for detecting information on the rotary disk,
A step motor is adopted in which the turntable is configured to rotate by an angle of 360 ° / 2 · m with respect to a rotation of ° / n.

In the above structure, the rotating disk and the detecting means can detect the rotation amount and the rotating direction of the rotor, and the pulse generation due to the vibration of the rotor at the time of step-out can be correctly detected as the cause of the step-out. At the same time, the time interval at the time of detection can be made coarse, and the control circuit can be simplified.

In order to achieve the above object, the present invention provides a rotor whose outer peripheral surface is equally divided and which is alternately magnetized to have different polarities, and at least two rotors facing the magnetized portion of the rotor.
One magnetic pole portion, at least two coils provided for each magnetic pole portion to excite the magnetic pole portion, and a region having a first light transmittance that is rotated in conjunction with the rotor and is equally divided in the circumferential direction. A turntable in which a region having a second light transmittance and a region having a third light transmittance are arranged in order, and a photointerrupter that detects the region as the turntable rotates. The step motor is characterized by including the following.

In the above-mentioned structure, even if the rotary disk uses a photointerrupter having a fine pitch and no resolution, the step-out of the rotor can be accurately discriminated.

In order to achieve the above object, the present invention has a rotor whose outer peripheral surface is equally divided and is alternately magnetized to have different polarities, and at least two rotors facing the magnetized portion of the rotor.
One magnetic pole portion, at least two coils provided for each magnetic pole portion to excite the magnetic pole portion, and a region having a first light reflectance that is rotated in conjunction with the rotor and is equally divided in the circumferential direction. A rotating disk in which areas having a second light reflectance and areas having a third light reflectance are arranged in order, and a photoreflector for detecting the area as the rotating disk rotates. The step motor is characterized by including the following.

In the above construction, even if the rotary disk uses a photoreflector having a fine pitch and no resolution, the step-out of the rotor can be accurately discriminated.

In order to achieve the above object, the present invention has a rotor whose outer peripheral surface is equally divided and is alternately magnetized to have different polarities, and at least two rotors facing the magnetized portion of the rotor.
In a step motor having one magnetic pole portion and at least two coils provided for each magnetic pole portion to excite the magnetic pole portion, the rotor is partially divided into equal parts in a circumferential direction at a first pitch. Area where different polarities are alternately magnetized,
The information recording unit has an information recording unit in which regions having different polarities at the second pitch and regions having different polarities at the third pitch are alternately arranged, and is recorded in the information recording unit of the rotor. The step motor is characterized by further comprising magnetic detection means for detecting the pitch by detecting the generated polarity.

In the above-mentioned structure, the rotor can prevent the step motor from increasing in size and can accurately detect the step-out of the rotor.

[0019]

Next, embodiments of the present invention will be described.

(Embodiment 1) FIGS. 1 to 8 and 18 are views for explaining the first embodiment. In FIG.
Indicates a lens holder for holding a lens, and a lens (not shown) is held in the inner diameter portion 1a of the lens holder 1.

Reference numeral 2 denotes a female thread ring, which is a female thread ring 2.
Has a female screw portion 2a, and is fitted and fixed to the concave portion 1b of the lens holder 1. Reference numeral 3 denotes a known stepping motor, the details of which will be described later with reference to FIGS. Reference numeral 4 denotes a male screw shaft fixed to the output shaft of the step motor 3, and this male screw shaft 4 is screwed with the female screw portion 2 a of the female screw ring 2.

Reference numeral 5 denotes a slit plate fixed to the output shaft of the step motor 3, the details of which will be described later with reference to FIG. Reference numeral 6 denotes a photo interrupter for detecting a pulse signal provided on the slit plate 5, reference numeral 7 denotes a guide shaft, and the guide shaft 7 is fixed to the portion 1c of the lens holder 1.

Reference numeral 8 denotes a guide tube fixed to a main body (not shown). A guide shaft 7 is slidably fitted in an inner diameter portion 8a of the guide tube 8 so that the lens holder 1 can be moved in the optical axis direction. To guide you to.

Reference numeral 9 denotes a spring, and this spring 9
Acts between the lens holder 1 and the base plate (not shown), and urges them in a direction away from each other in the optical axis direction. The rotation direction with the guide shaft 7 of the lens holder 1 as the center of rotation is restricted by the dowel 10 from the base plate (not shown) slidably fitted in the U-shaped groove 1d of the lens holder 1.

In these configurations, the step motor 3
The male screw shaft 4 is rotated by driving the lens holder 1
Accordingly moves in a direction parallel to the optical axis. The amount of movement is determined by the number of drive pulses of the step motor 3, but the drive load increases for some reason and causes a problem when the step motor 3 is driven in a state where step out has occurred. For this reason, the presence or absence of step-out is detected by the slit plate 5 and the photo interrupter 6.

Next, the step motor 3 will be described in detail. First, the step motor 3 is configured as described below. As shown in FIG. 2, the step motor 3 has a cylindrical shape, and is composed of a rotor 31 composed of a permanent magnet magnetized by being equally divided in the circumferential direction, a magnetic pole portion 32 a facing the magnetized portion of the rotor 31, Stator 32 with 32b
And magnetic pole portions 33a, 33 facing the magnetized portion of the rotor 31.
b and the magnetic pole portion 32 of the stator 32.
It is composed of a coil 34 for exciting a and 32b, and a coil 35 for exciting the magnetic pole portions 33a and 33b of the stator 33.

Next, the operation of the step motor 3 will be described with reference to FIGS. Magnetic pole portion 32a of the stator 32
Is the S pole and the magnetic pole portion 32b is the N pole so that the coil 34
To the N pole of the magnetic pole portion 33a of the stator 33 and the S pole of the magnetic pole portion 33b of the stator 33.
Takes the position shown in FIG. The position of this rotor is the initial position (Fig. 2).

When the energization of only the coil 35 is reversed from this state, the magnetic pole portion 33a of the stator 33 is excited to the S pole and the magnetic pole portion 33b is excited to the N pole, and as a result, the rotor 31 rotates clockwise. , To the position shown in FIG.

Further, when the power supply to the coil 34 is reversed from this state, the magnetic pole portion 32a of the stator 32 is excited to the N pole and the magnetic pole portion 32b is excited to the S pole, and the rotor 31 further rotates clockwise, as shown in FIG. Come to the position shown.

When the power supply to the coil 35 is reversed from this state, the magnetic pole portion 33a of the stator 33 is excited to the N pole and the magnetic pole portion 33b is excited to the S pole, and the rotor 31 further rotates clockwise, as shown in FIG. Come to the position shown.

Further, when the power supply to the coil 34 is reversed from this state, the coils 34 and 35 both return to the initial power supply state, the rotor 31 further rotates clockwise, and the phase becomes the same as the phase shown in FIG.

By repeating the switching of energization as described above, the rotor 31 rotates. In this way, when two coils are used and the energizing directions of these coils are switched four times in total, the magnetized position of the rotor 31 becomes the same as the original phase.

FIG. 6 shows how the energization of the coils 34 and 35 is switched. 6, a corresponds to the conduction phase shown in FIG. 2, b corresponds to the conduction phase shown in FIG. 3, and c corresponds to FIG.
5 corresponds to the energization phase shown in FIG. 5, and d corresponds to the energization phase shown in FIG. If each of a, b, c, and d is considered as one step, the rotor 31 has the same phase every four steps. If the stator motor is out of step for some reason and is driven again, a deviation of at least 4 steps will occur.

Next, the slit plate 5 will be described with reference to FIG. On the slit plate 5, light-shielding portions 5a and transmission portions 5b are radially formed to display binarized information. This is detected as a binary signal by the photo interrupter 6. The slit plate 5 is equally divided into three boundary areas A, B, and C in which the ratio of the light shielding portion 5a and the light transmitting portion 5b, that is, the duty ratio is different. That is, in the area A, the ratio of the light shielding portion 5a and the light transmitting portion 5b is 1: 3, in the area B, the ratio of the light shielding portion 5a and the light transmitting portion 5b is 1: 1, and in the area C, the light shielding portion 5a and the light transmitting portion 5b. The ratio is 3: 1.

FIG. 8 shows a signal when the rotation of the slit plate 5 is detected by the photo interrupter 6. A control circuit (not shown) can detect the rotational position of the slit plate 5 by detecting these duty ratios.

If the step motor 3 goes out of step, the rotor 3
If 1 vibrates, no matter where the rotor 31 is,
The change of duty ratio is 1/3 → 1/1 → 3/1 → 1/3
→ Since it does not change in an exact order like 1/1, it is possible to easily detect out-of-step.

Further, as described above, once the step-out occurs, a 4-step error occurs between the drive pulse and the actual rotation. Therefore, when the rotor 31 is rotated by 4 steps, the slit plate 5 is always formed in an area having a different duty ratio.
It is easier to detect out-of-step if it is positioned.

As shown in FIG. 9, in the slit plate 5, the area A having a duty ratio of 1/3 and the duty ratio of 1 are used.
A B area of / 1 and a C area of a duty ratio of 3/1 may be provided so as to be repeated a plurality of times in order and the change may be constantly detected, but the control circuit (not shown) must always detect the change. I have to. However, according to the method described above with reference to FIG. 7, the duty ratio may be detected every time at the same interval as the change of the energizing pulse, so that the detection becomes easy.

After four steps of driving, the energizing pulse is 36 when the number of magnetized poles of the rotor 31 is 2 · n.
When the slit plate 5 is rotated 0 ° / n and the number of repetitions of the A region, B region, and C region of the slit plate 5 is m, if the slit plate is configured to rotate 360 ° / 2. The duty ratio after the step can be changed.

In this embodiment, the number of magnetic poles of the rotor 31 is 4, and therefore n = 2, and the number of repetitions of the A area, B boundary area, and C area of the slit plate 5 is 1, so that m = 1.

The slit plate 5 is directly connected to the rotor 3 and the slit plate 5 so that the slit plate rotates 360 ° / 2 · 1 with respect to the rotation amount of the rotor 31 of 360 ° / 2. If the number of poles of the rotor is eight, it is sufficient to increase the speed by a gear or the like so that the swivel plate 5 rotates 180 ° with respect to the rotation 90 ° of the rotor.

In this embodiment, the slit plate 5 is used as the rotary disc for displaying the binarized information and the photo interrupter 6 is used as the detecting means for detecting the information, but other rotary discs may be used. The term "turning disc" used in the claims means a turning disc including a slit plate, and the term "detecting means" refers to a photointerrupter because it can have a configuration and another configuration as a detecting means. It should be noted that it is meant to include detection means.

FIG. 18 is a flow chart showing an example of the operation of the control circuit composed of a microcomputer for detecting the step-out and rotating the step motor by a predetermined amount in this embodiment. The operation will be described below with reference to FIG. In addition, in FIG. 18, P is the number of steps corresponding to a predetermined rotation amount.

(# 1): Q (corresponding to "the number of steps") = 1 is set.

(# 2): The energization phase to the coil of the step motor is switched, and the rotor is operated to advance one step.

(# 3): The photo interrupter 6 is driven, and the duty of the signal of the slit plate 5 at that time is detected.

(# 4): The value of the duty detected as the value corresponding to the step is stored in the memory circuit (not shown) in the control circuit.

(# 5): 1 is added to the value of Q.

(# 6): It is determined whether the value of Q is 5 or less, and the process returns to # 2 until the value of Q is 5. That is, the duty in each step of the first four steps (first four times of energization switching) is stored in advance for comparison of the values of the duty. The value of Q becomes 6 or more, driving is performed for 5 steps or more, the duty value corresponding to each step is detected in # 3, and each duty value is #
If it is determined that the data is stored in 4, the process proceeds to # 7.

(# 7): D (Q) (duty value at a certain number of steps) is compared with D (Q-4) (duty value 4 steps before). If the duty values differ as a result of the comparison, it is determined that step out has not occurred,
If it is the same, it is determined that step out has occurred.
Proceed to 8.

(# 8): In order to rotate by a predetermined rotation amount, it is necessary to rotate by one extra step, and 1 is added to the value of P.

(# 9): It is determined whether or not the actually driven step number Q exceeds the step number P required for rotating a predetermined amount. If not, the process returns to # 2 and the step is further advanced.

When Q reaches the value of P, the normal main sequence is resumed, the switching of energization is prohibited, and the rotor is stopped.

As described above, in this embodiment, it is possible to detect whether or not the step-out has occurred by comparing the duty at a certain step and the duty at the step four steps before.

(Second Embodiment) FIGS. 10 and 11 show a second embodiment. This embodiment is suitable when the photo interrupter has a structure in which slits with a fine pitch cannot be detected. By detecting the analog value of the output signal of the photo interrupter (not shown), the A area, B area, and C area of the rotating disk are detected.

FIG. 10 is a plan view of the rotating disk. The area A is made of a light-shielding portion, the area B is made of a semitransparent portion, and the area C is made of a transparent portion. FIG. 11 shows the analog output value of the photo interrupter. In this embodiment, the manner in which the analog output value changes is detected, and the step-out of the rotor is detected in the same manner as in the first embodiment depending on whether or not the changes are made in the correct order.

(Third Embodiment) FIGS. 12, 13, 14, and 15 show a third embodiment. In this embodiment, a photo reflector is used as the detecting means when the detecting means cannot detect slits having a fine pitch on the rotary disk. In this embodiment, similarly to the second embodiment, the A area, the B area, and the C area are detected by detecting the analog value of the output signal of the photo reflector which is the detecting means. FIG.
In FIG. 1, reference numeral 20 is a photoreflector, and other components are the same as those in FIG. 1 and are designated by the same reference numerals. Further, since other components have been described with reference to FIG. 1, description thereof will be omitted here.

FIG. 13 is a plan view of the turntable. In FIG. 13, the area A is a reflective surface, the area B is a semi-reflective surface, and the area C is a transparent portion. FIG. 14 shows the analog output value of the photo reflector. The change of the analog output value is detected, and whether or not the change is performed in the correct order is performed according to the first embodiment.
Step out of the rotor is detected in the same manner as.

(Modification of Third Embodiment) FIG. 15 shows a modification of the third embodiment. In the turntable shown in FIG. 13, the area A is made up of a reflective surface, the area B is made up of a semi-reflective surface, and the area C is made up of a transparent portion. By changing it, the A area, the B area, and the C area are formed. As shown in FIG. 15, the transmission holes are not formed in the area A, a certain number of transmission holes 5a are formed in the area B, and more (or larger) transmission holes are formed in the area C than the transmission holes formed in the area B. Form a hole.

(Fourth Embodiment) FIGS. 16 and 17 show a fourth embodiment. 16 and 17, a part of the rotor 31 (for example, the lower part) has a first magnetizing region and a second magnetizing region having different magnetizing pitches.
The magnetized area and the third magnetized area are equally divided in the circumferential direction and arranged. The change in the magnetization pitch is detected, and the step-out of the rotor is detected depending on whether or not the change is made in the correct order.

In FIG. 16, reference numeral 11 is an MR element,
A detection means for detecting magnetism such as a Hall element or a magnetic head is shown. The portion 31a of the rotor 31 is a magnetizing portion for generating a driving force as in the first embodiment, and the portion 31b is a magnetizing portion for detecting the rotational position of the rotor 31. The magnetized portion 31b is magnetized at different magnetizing pitches in the D region, the E region, and the F region, which are equally divided in the circumferential direction as shown in FIG. The detecting means detects the step-out of the rotor by the same method as that of the first embodiment, depending on whether or not the change in the magnetization pitch is correct. According to this embodiment, a rotary disk equivalent to the rotor 31 can be formed integrally with the rotor 31, so that the apparatus can be made compact.

[0062]

As described above, the step motor of the present invention has the following effects. (1) First, the step-out of the rotor can be reliably detected with a simple configuration. (2) Secondly, the control circuit can be simplified, and out-of-step of the rotor can be reliably detected with a simple configuration. (3) Thirdly, even if a detecting means having a fine pitch and no resolution is used, the step-out of the rotor can be surely detected. (4) Fourth, it is possible to make the step motor compact and to detect out-of-step reliably.

[Brief description of drawings]

FIG. 1 is a perspective view of a lens driving device of a camera using a step motor according to a first embodiment of the present invention.

FIG. 2 is a plan view of a step motor according to the first embodiment of the present invention.

FIG. 3 is a plan view of a step motor according to the first embodiment of the present invention.

FIG. 4 is a plan view of a step motor according to the first embodiment of the present invention.

FIG. 5 is a plan view of a step motor according to the first embodiment of the present invention.

FIG. 6 is a graph showing an energization waveform of a step motor.

FIG. 7 is a plan view of a turntable.

FIG. 8 is a graph showing the output of the photo interrupter.

FIG. 9 is a plan view showing another example of the turntable.

FIG. 10 is a plan view of a turntable according to a second embodiment of the present invention.

FIG. 11 is a graph showing the output of the photo interrupter of the second embodiment.

FIG. 12 is a perspective view of a lens driving device of a camera using a step motor according to a third embodiment of the present invention.

FIG. 13 is a plan view of a turntable.

FIG. 14 is a graph showing the output of the photo reflector.

FIG. 15 is a plan view showing a modified example of the turntable.

FIG. 16 is a perspective view of a rotor of Embodiment 4 of the present invention.

FIG. 17 is a partial perspective view of a rotor.

FIG. 18 is a flowchart showing the operation of the step motor of the first embodiment.

[Explanation of Codes] 3 step motor 31 rotor 32 stator 32a, 32b magnetic pole part 33 stator 33a, 33b magnetic pole part 34, 35 coil 5 turntable (slit plate) 6 detection means (photointerrupter) 20 detection means (photoreflector) 11 Magnetic detector

Claims (9)

[Claims] 1. A rotor whose outer peripheral surface is equally divided and is alternately magnetized to have different polarities, at least two magnetic pole portions facing the magnetized portion of the rotor, and magnetic pole portions provided for each magnetic pole portion. At least two coils to be excited, a signal pattern in which a binary signal is recorded at a first duty ratio by being rotated in conjunction with the rotor and equally divided in the circumferential direction, and a binary signal at a second duty ratio A rotary disc on which a recorded signal pattern and a signal pattern on which a binary signal is recorded at a third duty ratio are arranged in order; and a detection means for detecting information on the rotary disc. Step motor to do. 2. A rotor whose outer peripheral surface is divided into 2 · n equal parts and which are alternately magnetized to have different polarities, at least two magnetic pole parts facing the magnetized parts of the rotor, and for each magnetic pole part. At least two coils that are provided to excite the magnetic pole portion and are rotated in conjunction with the rotor and equally divided in the circumferential direction
A signal pattern in which a binary signal is recorded with a duty ratio of
A turntable in which m signal patterns each having a binary signal recorded at a second duty ratio and m signal patterns each having a binary signal recorded at a third duty ratio are arranged in order.
And a detecting means for detecting information of the turntable, wherein the turntable is 360 ° with respect to the rotation of 360 ° / n of the rotor.
A step motor configured to rotate by an angle of / 2 · m. 3. A rotor whose outer peripheral surface is equally divided and is alternately magnetized to have different polarities, at least two magnetic pole portions facing the magnetized portions of the rotor, and magnetic pole portions provided for each magnetic pole portion. At least two coils to be excited, a region that is rotated in conjunction with the rotor and is equally divided in the circumferential direction, and has a first light transmittance, a second light transmittance region, and a third light transmittance region. And a photo interrupter for detecting the regions in accordance with the rotation of the rotary disk. 4. A rotor whose outer peripheral surface is equally divided and which is alternately magnetized to have different polarities, at least two magnetic pole portions facing the magnetized portion of the rotor, and magnetic pole portions provided for each magnetic pole portion. At least two coils to be excited, a region that is rotated in conjunction with the rotor and is equally divided in the circumferential direction, and has a first light reflectance, a second light reflectance region, and a third light reflectance region. And a photoreflector for detecting the areas in accordance with the rotation of the rotary disk. 5. A rotor whose outer peripheral surface is equally divided and is alternately magnetized to have different polarities, at least two magnetic pole portions facing the magnetized portion of the rotor, and magnetic pole portions provided for each magnetic pole portion. In a step motor having at least two coils to be excited, a portion of the rotor is equally divided in the circumferential direction and is magnetized with different polarities alternately at a first pitch and at a second pitch. The magnetic recording medium has an information recording section in which areas having different polarities and areas having different polarities alternately arranged at a third pitch are arranged in order, and the polarities recorded in the information recording section of the rotor are A stepping motor, further comprising a magnetic detecting means for detecting the pitch by detecting the pitch. 6. The step motor according to any one of claims 1 to 5, wherein the signal patterns or the regions arranged in order on the turntable during rotation of the turntable or the rotor, or A stepping motor which detects a step-out according to whether or not the areas arranged in order on the rotor are detected in a predetermined order. 7. The step motor according to claim 1, wherein each of the signal patterns or each of the regions sequentially arranged on the turntable, or each of the signal patterns sequentially arranged on the rotor. Each of the regions is configured such that the detection means, photointerrupter, photoreflector or magnetic detection means detect different signal patterns or different areas when the rotor rotates to the same phase. A stepping motor which detects whether a different signal pattern or a different area is detected. 8. The step motor according to claim 1, wherein step number setting means for setting the number of steps, and energization for advancing the step by switching the energization of one of the coils after the step number is set by the step number setting means. Switching means, duty ratio storage means for storing the duty ratio of the signal pattern detected by the detecting means after the energization switching, and energization switching means for switching the energization by the set number of steps, and then the duty ratio storing means A step motor characterized by comparing the current duty ratio stored by the duty ratio and a duty ratio before a predetermined number of times, and detecting step-out from the result. 9. The step motor according to claim 8, wherein when step-out is detected, means for adding a number of steps necessary to obtain a rotation amount corresponding to the number of steps set in the step number setting means. A step motor further comprising: