JPH0520985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency generator suitable for being attached to a flat motor or the like built into a copying machine.

[Prior Art] Conventionally, for example, a DC flat motor has often been used to drive various parts of a copying machine, but a servo system is usually added to drive the flat motor at a required rotational speed. In this case, it is necessary to detect the actual rotational speed of the flat motor, and a frequency generator is usually used for this purpose.

That is, as shown in FIG. 4, this frequency generator has a rotating disk (rotor) 3 made of a steel plate (magnetic material) attached to a rotating shaft 1 of a flat motor via a brass hub 2. There is. As shown in FIG. 5, this rotating disk 3 has a large number of teeth 3a formed on its outer periphery.

Further, in a casing 4 made of a magnetic material that covers the rotating disk 3, a ring-shaped stator 5 made of a magnetic material is disposed coaxially with the rotating disk 3 on the outside of the rotating disk 3. A large number of teeth 5a are provided on the inner circumferential edge opposite to the outer circumferential edge of the rotating disk 3 at 5.
is formed (see Figure 5).

Further, a magnet 6 is disposed in the casing 4 so as to be close to the outer peripheral edge of the rotating disk 3, but at this time, the portion of the magnet 6 facing the rotating disk 3 is a north pole or a south pole. It is arranged so that. As a result, as shown by the dotted line in FIG. 6, a magnetic circuit connecting the magnet 6, rotating disk 3, stator 5, and casing 4 is formed, and as the rotating disk 3 rotates, the teeth 3a of the rotating disk 3 and When the relative position of the stator 5 to the teeth 5a changes, a change in magnetic flux occurs at the boundary between the rotating disk 3 and the stator 5.

In order to detect this change in magnetic flux, a search coil 7 is disposed in the casing 4 so as to be located near the boundary between the rotating disk 3 and the stator 5. This allows the search coil 7 to detect the rotational frequency of the rotating shaft 1.

Thereafter, the detection signal from the search coil 7 is used as a feedback signal for servo control of the flat motor.

In FIG. 4, 8 is a set screw for fixing the hub 2, and 9 is a bearing for the rotating shaft 1.

[Problems to be Solved by the Invention] However, in such a conventional frequency generator, the hub 2 made of a non-magnetic material is provided in order to block the magnetic flux leaking to the rotating shaft 1 side. In addition to the increased number of parts, there is a problem in that the hub 2 accounts for a large proportion of the cost of parts, leading to increased costs.

The present invention attempts to solve these problems, and provides a magnetically saturated rotor in which the conventionally required hub can be omitted by configuring the rotor as a magnetically saturated rotor. The purpose of the present invention is to provide a frequency generator having the following characteristics.

[Means for Solving the Problems] The frequency generator of the present invention has a rotor made of a magnetic material that is mounted directly on a rotating shaft, and that the rotor follows a first circular locus on the rotor. a plurality of slits formed discretely along the rotor with bottleneck portions between them; and a plurality of slits formed discretely along the rotor with bottleneck portions sandwiched from each other along a second circular locus concentric with the first circular locus on the rotor. A plurality of slits are provided, and each of the slits is arranged such that the bottleneck portion between the slits on the first circular locus and the bottleneck portion between the slits on the second circular locus are offset from each other. The rotor is characterized in that the inner peripheral side of the rotor exhibits a substantially non-magnetic action.

[Function] In the frequency generator having the magnetically saturated rotor of the present invention described above, when the motor etc. rotate and the rotor rotates, a relative position change between the teeth of the rotor and the stator occurs, resulting in a change in magnetic flux. When this happens, the search coil detects this change in magnetic flux, and as a result, the rotational frequency of the rotating shaft is detected. a plurality of slits formed discretely on the rotor, and a plurality of slits formed discretely on the rotor along a second circular locus concentric with the first circular locus, sandwiching the bottleneck from each other. At the same time, each slit is formed such that the bottleneck portion between the slits on the first circular locus and the bottleneck portion between the slits on the second circular locus are offset from each other, and Since the circumferential side substantially acts as a non-magnetic material, even if the rotor is directly attached to the rotating shaft, leakage of magnetic flux through the rotor to the rotating shaft side can be sufficiently prevented.

[Embodiments of the Invention] The present invention will be specifically described below with reference to illustrated embodiments. 1 to 3 show a frequency generator having a magnetically saturated rotor as an embodiment of the present invention. FIG. 1 is a front view of the magnetically saturated rotor, and FIG. 2 is a partial sectional view thereof. , FIGS. 3 a to 3 c are partial sectional views showing other fastening means for connecting the rotor and the rotating shaft, and in FIGS. 1 to 3, 4 to 6
The same reference numerals as in the figure indicate substantially similar parts.

Now, in the case of this embodiment as well, the frequency generator is applied to a frequency generator for detecting the rotational frequency of a flat motor for a copying machine, as shown in FIG. It has a rotating disk (rotor) 3 made of a steel plate (magnetic material) that is directly attached to the rotating shaft 1 of the rotor. As shown in FIG. 1, this rotating disk 3 has a large number of teeth 3a formed on its outer periphery.

Further, in a casing 4 made of a magnetic material that covers the rotating disk 2, a ring-shaped stator 5 made of a magnetic material is disposed coaxially with the rotating disk 3 on the outside of the rotating disk 3. A large number of teeth 5a are provided on the inner circumferential edge opposite to the outer circumferential edge of the rotating disk 3 at 5.
is formed.

Further, a magnet 6 is disposed in the casing 4 so as to be close to the outer peripheral edge of the rotating disk 3, but at this time, the portion of the magnet 6 facing the rotating disk 3 is a north pole or a south pole. It is arranged so that. As a result, the magnet 6, rotating disk 3,
A magnetic circuit connecting the stator 5 and the casing 4 is formed, and when the rotating disk 3 rotates, a relative position change between the teeth 3a of the rotating disk 3 and the teeth 5a of the stator 5 occurs. A change in magnetic flux occurs at the boundary with the stator 5.

In order to detect this change in magnetic flux, a search coil 7 is disposed in the casing 4 so as to be located near the boundary between the rotating disk 3 and the stator 5. This allows the search coil 7 to detect the rotational frequency of the rotating shaft 1.

By the way, as shown in FIG. 1, three arcuate slits 10 are discretely formed in the rotating disk 3 along the first circular locus 3A on the rotating disk 3, sandwiching a bottleneck portion 10a between them. At the same time, there is also a second circular locus concentric with the first circular locus 3A on the rotating disk 3.
Three arcuate slits 11 are formed discretely along the circular locus 3B with the bottleneck portion 11a interposed between them.

Further, the bottleneck portion 10 between the slits 10, 10
a and the bottleneck portion 11a between the slits 11, 11 are offset from each other.
11 is formed. As a result, the length of the magnetic flux circuit from the periphery of the rotating disk 3 to the mounting hole 3b on the rotating shaft 1 becomes longer, and since the bottleneck portions 10a and 11a are narrow, the rotating disk 3 is configured as a magnetically saturated rotor. . That is, since the rotating disk 3 is configured as a magnetically saturated type, the magnetic flux leaking to the rotating shaft 1 side through the mounting hole 3b of the rotating disk 3 can be significantly reduced.

Note that the rotating disk 3 is attached by tightening the screw 12 at the end of the rotating shaft 1, but in addition, as shown in FIG. Alternatively, the rotating disk 3 may be attached to the rotating shaft 1 using a retaining ring 13 and a leaf spring 14 as shown in FIG. 3b, or the rotating disk 3 may be attached to the rotating shaft 1 as shown in FIG. 3c. It may be attached by press-fitting or caulking into the rotating shaft 1.

With the above-described configuration, when the flat motor rotates and the rotating disk 3 rotates, a relative position change between the teeth 3a of the rotating disk 3 and the teeth 5a of the stator 5 occurs, and a change in magnetic flux occurs, the search coil 7 This magnetic flux change is detected by
At this time, the rotating disk 3 passes through a plurality of slits 10 that are discretely formed along the first circular locus 3A on the rotating disk 3 with bottleneck portions 10a in between. and a plurality of slits 11 that are discretely formed on the rotating disk 3 along a second circular locus 3B concentric with the first circular locus 3A, with bottleneck portions 11a in between. Since the slits 10 and 11 are formed such that the slit-to-slit bottleneck portion 10a on the first circular locus 3A and the slit-to-slit bottleneck portion 11a on the second circular locus 3B are offset from each other, the rotating disk 3 Even if it is attached directly to the rotating shaft 1, it is possible to sufficiently prevent magnetic flux from leaking to the rotating shaft 1 side through the rotating disk 3. This makes it possible to omit the conventionally required hub made of non-magnetic material, reducing the number of parts and the number of assembly steps, which greatly contributes to lower costs.

It goes without saying that the present frequency generator is not limited to use in the servo system of a flat motor for a copying machine.

[Effects of the Invention] As detailed above, according to the frequency generator having a magnetically saturated rotor of the present invention, since the rotor is configured as a magnetically saturated rotor, the hub that is conventionally required can be omitted. This has the advantage of reducing the number of parts and assembly man-hours, contributing to lower costs.

[Brief explanation of the drawing]

Figures 1 to 3 show a frequency generator having a magnetically saturated rotor as an embodiment of the present invention.
FIG. 1 is a front view showing the magnetically saturated rotor, FIG. 2 is a partial sectional view thereof, and FIGS. 3 a to 3 c are partial sectional views showing other fastening means for connecting the rotor and the rotating shaft. , Fig. 4 to Fig. 6 show a conventional frequency generator, Fig. 4 is a partial sectional view thereof, Fig. 5 is a front view showing its rotor and stator, and Fig. 6 is for explaining its operation. FIG. In the figure, 1... rotating shaft, 3... rotating disk (rotor), 3A... first circular locus, 3B... second
circular locus, 3a... tooth, 4... casing, 5...
...Stator, 5a... Teeth, 6... Magnet, 7... Search coil, 9... Bearing, 10, 11... Slit, 10a, 11a... Bottle portion between slits, 1
2...screw, 13...retaining ring, 14...plate spring.
In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A rotor made of a magnetic material that is attached to a rotating shaft and has a large number of teeth formed on its outer periphery, and a rotor that is disposed coaxially with the rotor on the outside of the rotor and that A stator made of a magnetic material and having a large number of teeth formed on opposing inner peripheral edges, a magnet disposed close to the rotor, and a stator disposed near the boundary between the rotor and the stator for rotation of the rotating shaft. In a frequency generator equipped with a search coil for detecting the frequency, the rotor is mounted directly on the rotating shaft, and the rotor is arranged in a discrete manner along a first circular locus on the rotor across the bottleneck from each other. A plurality of slits formed,
A plurality of slits are provided on the rotor along a second circular locus concentric with the first circular locus and are formed discretely across the bottleneck from each other. Each of the slits is formed such that the slit-to-slit bottleneck portion and the slit-to-slit bottleneck portion on the second circular locus are offset from each other, and the inner peripheral side of the rotor substantially acts as a non-magnetic material. , a frequency generator with a magnetically saturated rotor.