JP2610525B2 - Linear motor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor device such as an optical scanning device such as a copying machine and a printer, and a magnetic disk drive device using a linear motor including a mover and a magnetic field forming member. Things.

<Prior Art> Conventionally, in a linear motor device such as a magneto-optical disk device, as shown in FIG. 6, a movable element 72 composed of a voice coil or the like is arranged on a part of a movable body 71 that can move linearly.
A magnetic field forming member 73 composed of a permanent magnet or the like is fixed to the base frame 74.

<Problems to be Solved by the Invention> In the conventional linear motor device, in order to move the movable body 71, when the voice coil is driven to generate a thrust (F) on the movable element 72, a reaction force is applied to the magnetic field forming member 73. Occurs,
The reaction force (Fr) is transmitted to the base frame 74 and has an adverse effect such as the base frame 74 being vibrated or deformed. For example, a data error occurs in the disk device. Further, in a high-speed copying machine, there is a problem that the copying machine moves depending on an installation location, and a document moves.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear motor device that can eliminate inconvenience such as vibration of a base frame due to movement of a mover.

<Means for Solving the Problems> A linear motor device according to the present invention is provided with a movable element provided on a base frame so as to be linearly movable, and is disposed to face the movable element, and is generated by a driving force of the movable element. A magnetic field forming member that is moved in a counter-driving direction of the mover by a reaction force; and a return unit that returns the magnetic field forming member that has been displaced by the reaction force to a normal position. The motor for moving the magnetic field forming member is controlled based on the detection result of the moving position of the mover.

<Operation> When a driving force is generated between the mover and the magnetic field forming member,
The mover linearly moves on the base frame. At the same time
The reaction force generated by the driving force causes the magnetic field forming member to linearly move in the direction opposite to the mover. Therefore, the reaction force is not transmitted to the base frame. However, since the magnetic field forming member is deviated from the normal position due to the influence of the sliding load, the posture, and the like, the motor as the return means is controlled based on the detection result of the moving position during the movement of the mover. Then, the displacement of the magnetic field forming member is eliminated, and the positional relationship between the mover and the magnetic field forming member is always kept in the initial state.

<Embodiment> Hereinafter, an embodiment of a linear motor device according to the present invention will be described by taking a slit exposure type copying machine as an example. FIG. 1 is a plan view showing the mechanical structure of the linear motor device, FIG. 2, FIG. 3 is a sectional view taken along line XX, FIG. 4 is a sectional view taken along line YY, and FIG. FIG. 5 is a block diagram showing the electrical configuration of the apparatus, and FIG. 5 is an explanatory diagram of the operation of this embodiment.

The linear motor device shown here has a first movable body 10a on which an optical unit (not shown) such as a 45 ° mirror or a lamp unit is mounted and a second movable body on which an optical unit (not shown) such as a right angle mirror is mounted. 10b is provided on the base frame 1 inside the copying machine main body so as to move alternately in the A (scan direction) and B (return direction) directions in the figure at a speed ratio of 2: 1.

The first movable body 10a and the second movable body 10b are
Bearing 11 for supporting the shaft 3 mounted on the holder using the holder 2
a, 11b, and rollers 12a, 12b that slide on rails 4 attached to the base frame 1, respectively, so that they can be freely moved with respect to the base frame 1 in the directions A, B in the figure. . In addition, movers 20a and 20b are provided on both sides of the first mover 10a and the second mover 10b, respectively, and a magnetic field forming member is provided at a predetermined position at a position facing the movers 20a and 20b. 30a and 30b are provided respectively. In the figure, 13
a and 13b are linear encoders for detecting the moving positions of the first movable body 10a and the second movable body 10b, respectively, and the linear encoders 13a and 13b are shown in the drawing of the first movable body 10a and the second movable body 10b. The stator scale 13c is attached and fixed to the base frame 1 via the fixing member 5, while being fixed to the upper and lower portions, respectively.

The magnetic field forming members 30a and 30b are plate-shaped permanent magnets 31.
a, 31b and fixed yokes 32a, 32b, both ends of which are connected to each other by connecting plates 33, 34. That is, the magnetic field forming member 30a, the connecting plate 33, the magnetic field forming member 30b, the connecting plate 34b
Is a frame as a whole. Also, the magnetic field forming member 30
On both sides of the inner surface of a, bearings 35 corresponding to the shaft 3 are provided, respectively, while the lower part of the magnetic field forming member 30b is supported by a total of two rollers 6 attached to the base frame 1, Thus, the magnetic field forming members 30a, 30b connected by the connecting plates 33, 34 are connected to the base frame 1 by A, B in FIG.
It is movable in the direction.

Here, the mover 20a and the magnetic field forming member 30a will be described in detail. The mover 20a includes movable yokes 21a and 22a attached to both sides of the first movable body 10a, and three-phase coils 23a and 23a attached to outer surfaces of the movable yokes 21a and 22a. The forming member 30a includes a plate-shaped fixed yoke 31a connected to the connecting plates 33 and 34, and a permanent magnet 32a multi-polarized on the inner surface of the fixed yoke 31a in correspondence with the three-phase coil 23a.
This constitutes a three-phase brushless linear motor as a whole (this is referred to as a linear motor a). At predetermined positions of the movable yokes 21a and 22a, illustrated are Although not shown, each Hall element for detecting the magnetic flux of the permanent magnet 32a is provided to give the timing of the excitation switching of the three-phase coil 23a. However,
Three-phase brushless linear motor composed of mover 20b and magnetic field forming member 30b (this is referred to as linear motor b)
Furthermore, the description is omitted because the same is true for the magnetic field forming member 30a.On the outer surface of the fixed yoke 31a, columns 41a and 41b are provided to project outward, respectively, and the columns 41a and 41b Are taken out of the base frame 1 through cutout holes 42a and 42b formed in the side surface of the base frame 1 (see FIG. 3). A pulley 45 wound around a wire 43 stretched with a predetermined tension is provided between the cut-out holes 42a and 42b outside the base frame 1 between the cut-out holes 42a and 42b. Have been. The pulley 45 is a gear box fixed to the outer surface of the base frame 1 together with the timing pulley 46.
The pulley 45 and the timing pulley 46 are supported by a timing belt 48. Further, a pulse motor 49 is provided on the outer surface of the gear box 47, and its output shaft is connected to the timing pulley 46.

That is, the pulse motor 49 is driven to drive the timing pulley.
When the 46 rotates alternately, the pulley 45 alternately rotates at a reduced speed through the timing belt 48. Further, as the pulley 45 rotates alternately, the wire 43 and the support 41 are rotated.
a, 41b, the magnetic field forming members 30a, 30b connected to each other by the connecting plates 33, 34 are alternately moved in the directions A, B in FIG.
0). A spring 44 for stabilizing the wire tension and absorbing a sudden load change at the time of return is interposed between the support 41b corresponding to the return side and the wire 43.

Note that the combination of the timing belt 48 and the timing pulley 46 as the return means 40 employs a speed reduction mechanism.
This is to prevent operation instability due to backlash in gear connection.

Next, the linear motor control circuit 50 will be described with reference to FIG.

The position detection signals of the linear encoders 13a and 13b
A 90-degree A-phase signal and a B-phase signal and a Z signal for origin detection are guided to the MPU 51 as a microprocessor through the waveform shapers 51a and 51b, and the first movable body 10a and the second movable body
The data of the moving position 10b is sequentially introduced into the MPU 51.

In the MPU 51, data of speed patterns of the first movable body 10a and the second movable body 10b is input in advance, and command position data based on the speed patterns and the waveform shapers 51a, 51a, 5b.
The present position data is compared with the current position data based on the output signal of 1b, and the result of the comparison is sequentially output to the three-phase drivers 52a and 52b as a signal. In these three-phase drivers 52a and 52b
The circuit is configured to generate a current according to a signal from the MPU 51, and is supplied to the three-phase coils 23a and 23b in the linear motors a and b, respectively.

That is, the linear motor control circuit 50
The thrusts of the linear motors a and b are independently controlled by using the position detection signals of 13a and 13b as feedback signals,
a, The speed of the second movable body 10b is controlled in a closed loop. This is the main function of the linear motor control circuit 50.
It also has the function of controlling

The pulse motor drive circuit 60 includes a linear motor control circuit 50
Count-up pulse derived from
a and count pulse Dn-a and initialize signal Up-
i, Dn-i, and a logic unit 62 for predetermined processing of an input signal passed through the input signal switch SW6.
And a four-phase current driver 63 for supplying a phase current corresponding to a predetermined processed input signal to a pulse motor 49, which is a four-phase pulse motor. 1/8 step angle of 49
The basic configuration is such that microstep driving (also referred to as 2W1-2-phase driving or vernier driving) for dividing angles is performed. The pulse motor 49 is micro-step driven to smooth the rotation of the rotor and at the same time to improve the driving frequency.

More specifically, when the power is turned on, the input signal switch SW61 is automatically set to the i side shown in the figure, and the first movable body 10a and the second movable body 10b return to the predetermined standby positions. When no signal is given from the MPU 51, the movement of the magnetic field forming members 30a and 30b is prohibited, but the first movable body 10a and the second movable body 10b are at predetermined standby positions. Upon returning, the initialization signals Up-i and Dn-i are introduced from the MPU 51, and the pulse motor 49 operates in response to the signals to move the magnetic field forming members 30a and 30b to a predetermined standby position. ing. When this initialization operation is completed, the input signal switch SW61 is automatically set to the s side shown in the figure, and thereafter, the count-up pulse Up-a for providing the moving position of the first movable body 10a is provided. The pulse motor 49 can operate according to the countdown pulse Dn-a. The operation of the pulse motor 49 will be described later. The reason why the pulse motor drive circuit 60 is controlled by the count-up pulse Up-a and the count-down pulse Dn-a is to reduce the processing load on the MPU 51.

By the way, the output of the three-phase driver 52a in the linear motor control circuit 50 indicates the respective states of the first movable body 10a during the acceleration / deceleration operation, the low-speed feed and the standby, and the output switching signal PS-a derived from the MPU 51. The output switching signal PS-a is also introduced to the four-phase current driver 63 to operate in the same manner, so that the phase current of the pulse motor 49 is reduced. It is designed not to affect the electric angle of the field. In other words,
In the constant speed feed period and the standby period in which no load is applied to the pulse motor 49, the phase current is reduced without impairing the field electrical angle, thereby reducing the heat generation of the pulse motor 49.

With the linear motor device configured as described above, the speed of the first movable body 10a and the second movable body 10b is controlled according to the speed pattern shown in FIG.

Here, thrusts Fa (t) and Fb are applied to linear motors a and b.
(T) are respectively generated, and the first movable body 10a and the second movable body 1
If 0b is moved in the scanning direction (A direction), the magnetic field forming members 30a and 30b exert a reaction force Fr (= −Fa (t) −Fb).
(T)) acts, and the reaction force Fr causes the magnetic field forming member 30.
a and 30b move in the B direction.

Thereafter, when the first movable body 10a and the second movable body 10b are returned in the return direction (B direction), the magnetic field forming members 30a and 30b are moved in the A direction by a reaction force against the thrust of the linear motors a and b based on the return operation. Go to

When the first movable body 10a and the second movable body 10b are alternately moved in this way, the magnetic field forming members 30a and 30b alternately move in opposite directions, so that the reaction force Fr does not act on the base frame 1. As a result, the base frame 1 caused by the reaction force Fr
Does not occur.

However, by driving the pulse motor 49, the magnetic field forming member
When moving 30a, 30b, the reaction force at this time acts on base frame 1 through pulse motor 49, and base frame 1 may vibrate. Just pulse motor 49
The distance by which the magnetic field forming members 30a and 30b are moved is only the amount of displacement of the magnetic field forming members 30a and 30b due to a frictional load, an inclination of the device, and the like (details will be described later). The level of the reaction force is much smaller than the reaction force Fr, and the vibration of the base frame 1 due to this is practically negligible.

The magnetic field forming members 30a and 30b receive both reaction forces due to the movement of the first movable body 10a and the second movable body 10b when there is no loss without frictional load, inclination of the apparatus, and the like, and only the mass ratio with the movable body is obtained. Move while maintaining the ideal position determined by. as a result,
When the first movable body 10a and the second movable body 10b return to the predetermined standby positions, the magnetic field forming members 30a and 30b also return to the predetermined standby positions,
The deviation is zero.

However, the magnetic field forming members 30a and 30b are returned to the original state only in the ideal state. If the attitude of the linear motor device with respect to the scan direction is not horizontal, the first movable body 10a and the second Movable body 10b and magnetic field forming member
Due to the influence of the component of the moving direction of the own weight of 30a, 30b, the magnetic field forming members 30a, 30b are displaced with the movement of the first movable body 10a, the second movable body 10b, as shown in FIG. Becomes larger.

In the linear motor device of the present invention, even if there is a loss such as a friction load or a tilt of the device, control is performed so that the deviation becomes zero. The principle is as follows.

First, the mass of the first movable body 10a is m1, its acceleration is a1, the mass of the second movable body 10b is m2 (= m1), and its acceleration is a1.
Assume 2. Since the speeds of the first movable body 10a and the second movable body 10b are controlled at a speed ratio of 2: 1, a2 = a1 / 2. When the mass of the magnetic field forming members 30a, 30b and the like is mg and the acceleration is ag, the reaction force acting on the magnetic field forming members 30a and 30b and the like is represented by the following equation when there is no loss such as a frictional load. expressed.

F = − (m1 · a1 + m2 · a2) = − (3/2) (a1 · m1) F = mg · ag The following relationship is established from the equation.

ag = − (3m1 · a1) / (2mg) When the moving position of the first movable body 10a after t seconds is x1 (t), and the moving positions of the magnetic field forming members 30a and 30b are xg (t). , X1 (t) = a1 · t ² ... Xg (t) = ag · t ² .

xg (t) = − (3 ml / 2 mg) · x1 (t) When the moving position of the first movable body 10a is known from the equation, the ideal positions of the magnetic field forming members 30a and 30b at that time can be obtained. I understand.

In merits of the linear motor unit drives the pulse motor 49 by operating the pulse motor drive circuit 60 based on the count up pulse U _pa and count down pulse D _na gives the movement position of the first movable member 10a, the magnetic field forming members 30a , 3
Control is performed so that 0b is always kept at the ideal position. In other words, the rotational force of the pulse motor 49 is controlled so that the magnetic field forming members 30a and 30b are always kept at the ideal positions. As a result, even if there is a loss such as a friction load, the loss is canceled by the rotational force of the pulse motor 49. Therefore,
When the first movable body 10a and the second movable body 10b return to the predetermined standby positions, the magnetic field forming members 30a and 30b also return to the predetermined standby positions,
The excursion also approaches zero.

The linear motor device according to the present invention can be applied not only to a copying machine but also to an optical scanning mechanism such as a printer, a magnetic disk drive, and the like.
In this embodiment, the pulse motor 49 is employed as the return means from the viewpoint of simplification of the electric circuit and cost reduction as a whole. However, in addition to the position detection signal of the first movable body 10a, the pulse motor 49 is formed. It is also possible to prepare a position detection signal of the members 30a and 30b, form a servo system using the former as a reference signal, and use the latter as a feedback signal, and adopt a form in which a servo motor is employed.

<Effect of the Invention> As described above, in the case of the linear motor device according to the present invention, the reaction force generated by the driving force is not transmitted to the base frame, and the displacement of the magnetic field forming member based on the reaction force is eliminated. Configuration, so that inconveniences such as vibration of the base frame due to the movement of the mover can be eliminated, and the magnetic field forming member can be properly adjusted without being affected by friction loss, device inclination, etc. Can be restored. In addition, since the return means is controlled in accordance with the detection result of the movement position of the motor mover for moving the magnetic field forming member, there is an advantage that the control system can be simplified.

[Brief description of the drawings]

FIGS. 1 to 5 are views for explaining an embodiment of the linear motor device according to the present invention. FIG. 1 is a plan view showing a mechanical configuration of the linear motor device, and FIG.
FIG. 3 is a sectional view taken along line XX in FIG. 1, and FIG.
FIG. 4 is a cross-sectional view taken along line -Y, FIG. 4 is a block diagram showing an electrical configuration of the linear motor device, and FIG. 5 is an operation explanatory diagram of the present embodiment. FIG. 6 is a schematic diagram for explaining a conventional linear motor device. 1 Base frame 20a, 20b Mover 30a, 30b Magnetic field forming member 40 Return means 49 Pulse motor

Claims (1)

(57) [Claims] A movable member provided on the base frame so as to be linearly movable; and a movable member disposed opposite to the movable member, the movable member being moved in a counter-driving direction of the movable member by a reaction force generated by a driving force of the movable member. A magnetic field forming member, and return means for returning the magnetic field forming member displaced by the reaction force to a normal position. As the return means, a motor for moving the magnetic field forming member is movable. A linear motor device, wherein the control is performed in accordance with a detection result of a movement position of a child.