JPH0368593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reading device in an information input device such as a facsimile machine, in particular, to relatively move a document table and an optical unit that photoelectrically reads a document on the document table. It relates to a drive device.

2. Description of the Related Art In a reading device, a rotary motor, such as a pulse motor, is usually used as a power source for a drive device that moves an optical unit along a document table.

On the other hand, a printer head drive device using a linear pulse motor is known. A linear pulse motor is a linear pulse motor developed by developing a conventional rotary pulse motor in a straight line.As shown in Figure 4, a linear pulse motor is a fixed motor with many parallel grooves formed in a comb-like shape in its cross section. A scale 14 and a slider 15 that runs along this fixed scale 14
and a guide roller 17 that is held by the slider 15 and rolls into contact with the fixed scale 14 so as to keep the distance between the slider 15 and the fixed scale 14 constant. The scale 14 corresponds to the stator of a conventional rotary pulse motor, and the slider 1
5 corresponds to the rotor.

As shown in FIG. 5, the slider 15 has electromagnets 35 and 36 each having a U-shaped cross section fixed to different polarity portions of a permanent magnet 34 provided at the bottom of a table 33. The coil is moved on the scale 14 by passing current through the coil alternately in different directions. For example, when a positive current is applied to the electromagnet 35, the magnetic force generated at the a pole is transferred to the permanent magnet 34, since the coil is wound in opposite directions with the a and b poles.
The magnetic force is applied to the scale 14, and the scale 14 assumes a position closest to and facing the teeth A, and becomes stable. On the other hand, the magnetic force generated at the b pole is the permanent magnet 34
It works to cancel the magnetic force of. Next, electromagnet 3
When a positive current is applied to the scale 6, the d pole and the tooth D attract each other, and the slider 15 moves rightward by 1/4 of one pitch P of the tooth of the scale 14. Next, when a negative current is applied to the electromagnet 35, the b pole and tooth B attract each other, and the slider 15 moves 1/4 pitch to the right.Subsequently, when a negative current is applied to the electromagnet 36, The c-pole and the tooth C attract each other, and the slider 15 further advances by 1/4 pitch. Then, by applying a positive current to the electromagnet 35 again, and subsequently applying current in the same manner, the slider 15 can be sequentially moved to the right.

A linear pulse motor with this configuration has a high degree of stopping accuracy, and normally, as shown in Figure 6,
A slider 15 is arranged on the lower side of the fixed scale, and a guide roller shaft 3 fixed to the slider 15
A fixed adapter 38 is provided at the tip of the fixed scale 14, and a side roller 39 held by the fixed adapter 38 is brought into contact with the side surface of the fixed scale 14 to regulate its position in the lateral direction. Note that a driven portion (not shown) such as a print head is held by a fixed adapter 38.

Problems to be Solved by the Invention As mentioned above, since the drive device in the conventional reading device uses a rotary motor, it requires a mechanism to convert the rotation of the motor into linear motion of the optical unit, making the device complicated. Not only that, but there was also a limit to increased speed and accuracy due to backlash and slips within the mechanism.

Therefore, the inventor came up with the idea of using a linear pulse motor used in the head drive mechanism instead of the conventional rotary motor, and fixed the scale that makes up the linear pulse motor to the frame of the device to make it a fixed scale, and the slider The optical unit is connected to and held by a slider, and the optical unit is moved directly by a slider. However, a problem has arisen in that simply using a conventional linear pulse motor as a driving device in a reading device does not satisfy the required constant speed. In other words, conventional linear pulse motors used in printer head drive mechanisms only take into account the rise characteristics, establishment characteristics, and stopping accuracy of the slider, and do not take constant speed during movement into consideration, making them difficult to read documents. It was not possible to satisfy the required constant speed of the optical unit movement.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a reading device equipped with a device capable of moving an optical unit or a document table at a predetermined constant speed in the reading device. .

Problems to be Solved by the Invention As a result of intensive studies to solve the above problems, the inventor found that in general, in linear pulse motors, when the slider is turned off, the slider wobbles (called cogging), and as a result, the slider does not move at a constant speed. It has been found that this cogging can be reduced by making the rotation of the guide roller heavier.

The first invention based on this knowledge is
A friction member is brought into contact with a guide roller that is held by a slider of a linear pulse motor and travels on the fixed scale in rolling contact with the fixed scale, and the rotation of the guide roller is made heavier by friction.

In addition to the configuration of the first invention, a second invention provides a U-shaped damping material on the fixed scale of the linear pulse motor, with both ends thereof being perpendicular to the surface of the fixed scale on the slider side. The guide roller is attached so as to protrude, and the side surface of the guide roller is pressed against the inner surface of the protruding portion of the vibration damping material.

Effects As described above, in the present invention, a friction member is pressed against the guide roller to apply frictional force to increase the rotation speed, thereby reducing cogging of the slider and improving constant speed characteristics.

Moreover, the second invention has the above-mentioned structure,
The damping material can prevent the fixed scale from vibrating and further reduce cogging. Further, by the configuration in which guide rollers are pressed against the inner surfaces of the ends of the U-shaped damping members, the lateral position of the slider with respect to the fixed scale is regulated, and side rollers as in the conventional case are not required.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

Figures 1 to 3 show the reading device of this embodiment, with Figure 1 being a side view, Figure 2 being a front view, and Figure 2 being a front view.
FIG. 3 is a perspective view of the main part. In the figure, reference numeral 1 denotes a document table, which includes a document table glass 2, a document 3, a document presser 4, and the like. This document table 1 is provided stationary at a fixed position. Reference numeral 5 denotes an optical unit that can run along the document table 1, and has inside thereof a fluorescent lamp 6, a reflecting mirror 7, a condensing lens 8, a reading element 9, a drive circuit 10, and the like. Reference numeral 11 denotes a drive device for running the optical unit 5, which includes a fixed scale 14 fixed to the base 12 of the reading device via a fixed base 13, a slider 15 running along the lower surface of the fixed scale 14, and a drive device attached to the slider 15. a guide roller shaft 16,
The optical unit 5 has a linear pulse motor consisting of guide rollers 17A, 17B, etc., which are rotatably held on the guide roller shaft 15 and roll into contact with the lower surface of the fixed scale 14.
is fixed and held on the guide roller shaft 16 by means of fixing it to the guide roller shaft 16, that is, a fixing adapter 18, a grip 19, etc.

The fixed scale 14 has a U-shaped damping material 20.
However, both ends of the slider 15 have a fixed scale 14.
It is attached so that it protrudes further from the side surface at a right angle. The vibration damping member 20 is used to impart rigidity to the fixed scale 14 to prevent vibration of the fixed scale 14 and to regulate the running position of the guide rollers 17A, 17B, and is usually made by press working a metal plate. The inner surfaces facing each other are finished smooth. The vibration damping member 20 may be directly attached to the fixed scale 14 with an adhesive, screws, etc., or may be attached via a vibration absorbing material such as rubber. Guide rollers 17A and 17B arranged on both sides of the slider 15 are both rotatably provided with respect to the guide roller shaft 16, and at least one guide roller 17B is provided so as to be movable in the axial direction. Slider 15 and one guide roller 17A
(The one on the right side of Figure 2) is provided with a friction member 22,
A sleeve 23 is arranged and the other guide roller 1
7B, a spring 24 and a friction member 22 are arranged. The spring 24 is attached to each guide roller 17A, 1
7B, and constitutes means for pressing the side surfaces of each guide roller 17A, 17B against the inner surface of the protrusion of the vibration damping member 20. The driving member 22 is in contact with the guide roller 17A or 17B to apply frictional resistance to the guide roller 17A or 17B to make the rotation of the guide roller 17A or 17B heavier, and may have an arbitrary shape such as a washer shape or a sleeve shape. is available. This friction member 2
2 may be rotatable with respect to the guide roller shaft 16 as long as it is provided so as to be in frictional contact with both the guide rollers 17A, 17B and the non-rotating portion. For example, if the guide rollers 17A, 17B are the outer rings of ball bearings. If the friction member 22 is large enough to contact both the inner ring and the outer ring of the ball bearing, the friction member 22 is simply attached to the guide roller shaft 16.
All you have to do is attach it to the As the material, any material having an appropriate coefficient of friction and wear resistance is suitably used, such as rubber, plastic, plastic in which graphite is dispersed (trade name: "Polyslider", etc.), asbestos, etc. The friction member 22 on the right side of FIG. 2 may be integrally constructed with the sleeve 23, or may be fixed to the guide roller shaft 16. In FIG. 1, reference numeral 26 indicates rubber feet that support the machine base 12.

Next, the operation of the above device will be explained. The original 3 placed on the original platen glass 2 is fixed with the original presser 4, the original 3 is irradiated with a fluorescent lamp 6, the reflected light is changed to an optical path by a reflecting mirror 7, and is placed on the reading element 9 by a condensing lens 8. The light is focused at the reading element 9 by the drive circuit 10.
is electronically main-scanned and processes such as photoelectric conversion are performed.

On the other hand, the sub-scanning is performed by moving the slider 15 holding the optical unit 5 along the fixed scale 14 at a predetermined speed. During this traveling, the guide roller 17 held by the slider 15
A and 17B are guided by the inner surface of the tip of the damping member 20 that protrudes downward from both sides of the fixed scale 14, and the distance between the guide roller 17A on the right side of FIG. 2 and the slider 15 is always constant, so that the slider 15 and the optical unit 5 held therein move accurately at predetermined positions. Further, as the slider travels, the guide rollers 17A and 17B contact the lower surface of the fixed scale 14 and the vibration damping member 20 and rotate, but since the friction member 22 contacts the guide rollers and provides frictional resistance, the slider The occurrence of cogging in No. 15 is reduced, and the constant speed of the slider running is improved.

In the above embodiment, the optical unit 5 is configured to move relative to the stationary document table 1, but instead of this, the document table 1 is connected to a slider of a linear pulse motor, and the document table 1 is moved. Good too. Furthermore, it goes without saying that the optical unit is not limited to that of the illustrated embodiment, and may be constructed of a contact image sensor.

Effects of the Invention As is clear from the above description, in the present invention, the first and second inventions provide frictional resistance by bringing the friction member into contact with the guide roller held by the linear pulse motor. The constant speed of the slider can be improved, and as a result, the linear pulse motor can be applied to move the optical unit or document table in the reading device.

Furthermore, the second invention prevents vibration of the fixed scale by attaching a U-shaped vibration damping member to the fixed scale, so that the constant speed of the slider can be further improved. In addition, the running position of the slider is regulated by pressing the side surface of the guide roller against the inner surface of the tip of the vibration damping member.
This eliminates the need for conventional side rollers and has the advantage of simplifying the structure.

[Brief explanation of drawings]

Fig. 1 is a schematic side view showing a preferred embodiment of the present invention, Fig. 2 is a schematic front view, Fig. 3 is a schematic perspective view of a linear pulse motor used in this embodiment, and Fig. 4 is a conventional linear pulse motor. Schematic perspective view of pulse motor, fifth
The figure is an explanatory diagram of its operation, and FIG. 6 is a schematic front configuration diagram of a conventional linear pulse motor. DESCRIPTION OF SYMBOLS 1... Document table, 2... Document table glass, 5... Optical unit, 11... Drive mechanism, 14... Fixed scale, 15... Slider, 16... Guide roller shaft, 17A, 17B... Guide roller , 18...
... Fixed adapter, 20 ... Damping member, 22 ... Friction member, 24 ... Spring.

Claims (1)

[Scope of Claims] 1. A driving device for a reading device that relatively moves a document table and an optical unit that photoelectrically reads a document on the document table, which comprises a stationary fixed scale and the fixed scale. a linear pulse motor having a slider that moves along the slider, a guide roller that is held by the slider and rolls into contact with the fixed scale so as to maintain a constant distance between the slider and the fixed scale, and a guide roller that is fixed to the slider. A driving device for a reading device, comprising means for fixing the document table or the optical unit to a shaft, and further comprising a friction member in which the linear pulse motor contacts the guide roller to increase rotation. 2. A driving device for a reading device that relatively moves a document table and an optical unit that photoelectrically reads the document on the document table, which comprises a fixed scale provided stationary, a slider that moves along the fixed scale, , a linear pulse motor having a guide roller that is held by the slider and rolls into contact with the fixed scale so as to maintain a constant distance between the slider and the fixed scale; and the document table is attached to the guide roller shaft fixed to the slider. or a means for fixing the optical unit, and the linear pulse motor further includes a U-shaped vibration damping member attached such that both ends thereof protrude at right angles from the slider side surface of the fixed scale; A driving device for a reading device, comprising means for pressing a side surface of the guide roller against an inner surface of a protrusion of a vibration damping member, and a friction member that comes into contact with the guide roller to make rotation heavier.