JPH0368594B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reading device for an information input device such as a facsimile machine, and more particularly to a reading device that moves an optical unit for photoelectrically reading a document on a document table along the document table. The present invention 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 mechanism that moves an optical unit along a document table.

On the other hand, a printer head drive mechanism 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 8, a linear pulse motor has a scale with many parallel grooves formed in a comb-like shape in its cross section. 14, a slider 15 that runs along the scale 14, and a guide roller 17 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. The scale 14 corresponds to the stator of a conventional rotary pulse motor, and the slider 15 corresponds to the rotor.

As shown in FIG. 9, 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 out the magnetic force of. Next, electromagnet 3
When a positive current is applied to the scale 14, the d-pole tooth D attracts each other, and the slider 15 moves rightward by 1/4 of the tooth pitch P of the scale 14. Next, when a unidirectional current is passed through the electromagnet 35, the b pole and tooth B attract each other, and the slider 15 further moves 1/4 pitch to the right.Subsequently, when a unidirectional current is passed through the electromagnet 36, , the c pole and the tooth C attract each other and the slider 15
advances another 1/4 pitch. Then, the electromagnet 35 again
The slider 15 can be sequentially moved to the right by passing a current in the + direction through and thereafter passing a current in the same manner.

A linear pulse motor with this configuration usually has a first
As shown in FIG. 0 and FIG. 11, a slider 15 is disposed on the lower surface side of the scale 14, and a fixed adapter 18 is provided at the tip of a guide roller shaft 37 fixed to the slider 15. The driving portion 39 is held. The loads of the driven portion 39, slider 15, etc. are supported by the attraction force of the fixed scale due to the magnetic force of the permanent magnet 25 of the slider 15, electromagnet, etc.

This adsorption force has a limit guaranteed by the above-mentioned magnetic force balance, and in order to automatically return to the original state when an excessive external force is applied to the slider 15 and the slider separates from the fixed scale, it is necessary for the slider 15 to separate from the scale 14. Distances must be regulated. For this reason, conventionally, the stopper 40 is fixed to the fixed adapter 18 to regulate the distance e between the stopper 40 and the fixed scale.

Problems to be Solved by the Invention As mentioned above, the drive mechanism of the conventional reading device uses a rotary motor, which 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 present inventors came up with the idea of using a linear pulse motor used in the head drive mechanism instead of the conventional rotary motor, and used the optical unit as the driven part 39 in the mechanism shown in FIGS. 10 and 11. We have developed a mechanism in which the However, it was discovered that this mechanism has further improvements.
That is, the stopper 40, which regulates the maximum distance that the slider 15 is separated from the lower surface of the scale, is usually made using a press, so the machining accuracy is not very high. It was necessary to set each stopper one by one so that they would be at a certain distance using a screwdriver, and a great deal of effort was required to assemble and adjust the stopper. Furthermore, even if the processing precision of this stopper was improved, it was not a solution.
This is because the movement of the optical unit of the reading device requires a high level of constant speed, and it has been found that this speed can be improved by attaching a suitable damping material to the top surface of the scale. When the damping material is bonded using an adhesive or through rubber, the precision of the upper surface thereof is extremely poor, and therefore, even if the processing precision of the stopper is improved, it is necessary to make adjustments in the manufacture and assembly of the stopper. Furthermore, when the slider fails, it cannot be replaced unless the stopper is removed, and the stopper must be readjusted and reassembled after replacement.

Note that if the slider is placed on the top side of the scale, the problem of falling will disappear and the above problem will be solved, but in this case, if an external force is applied to the slider, it may come off laterally from the scale, and it may cause some damage. It cannot be adopted because it requires a prevention means, and if the surface of the scale on which the guide roller runs faces upward, dirt and dust will easily adhere to it, causing abnormal running such as wobbling of the guide roller.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a drive mechanism for a reading device that can prevent a slider from falling without requiring special adjustment.

Means for Solving the Problems In order to solve the above problems, the present invention forms a cutout hole extending in the longitudinal direction of the fixed scale in the vibration damping material provided on the top surface of the fixed scale, exposes the top surface of the fixed scale, and optically The unit has a structure in which a convex portion is provided on a portion facing the upper surface of the fixed scale, the tip of which is located within the notch hole of the damping material and is formed at a predetermined distance from the upper surface of the fixed scale. It is something that

Function Since the present invention has the above-mentioned configuration, even if some external force is applied to the optical unit held by the slider and the slider falls from the fixed scale, the convex part of the optical unit will come into contact with the upper surface of the fixed scale and the fall will be prevented. This can be prevented and the slider can be immediately restored by the magnetic force of the permanent magnet. At this time, the falling distance of the slider is the distance between the normal convex part and the top surface of the fixed scale.The top surface of the fixed scale has high machining accuracy, and it is easy to improve the machining accuracy of the convex part, so each predetermined distance is determined. By manufacturing and assembling with precision, it is possible to achieve a predetermined spacing without having to adjust each machine one by one.

Embodiments Hereinafter, preferred embodiments of the present invention shown in the drawings will be described.

FIG. 1 is a side sectional view showing a schematic configuration of a reading device according to an embodiment of the present invention, and FIG. 2 is a front sectional view of a portion thereof. Reference numeral 1 denotes a document table, which includes a document table glass 2, a document 3, a document holder 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. Note that the optical unit 5 may be composed of a contact image sensor. Reference numeral 11 denotes a drive mechanism for moving the optical unit 5, which includes a fixed scale 14 fixed to the base 12 of the reading device via a fixed base 13;
From a slider 15 running along the lower surface of the fixed scale 14, a guide roller shaft 16 attached to the slider 15, guide rollers 17A and 17B rotatably held by the guide roller shaft 16 and rolling into contact with the lower surface of the fixed scale 14, etc. The optical unit 5 is held on the guide roller shaft 16 by a fixed adapter 18. The fixed adapter 18 and the guide roller shaft 16 constitute means for holding the optical unit on the slider.

The fixed scale 14 has a U-shaped damping material 20.
is attached so that its both ends protrude further at right angles from the surface of the fixed scale 14 on the slider side.
The damping material 20 is used to impart rigidity to the fixed scale 14 to prevent vibration of the fixed scale, and also to regulate the traveling position of the guide rollers, and is usually made by pressing metal plates, but it is not only possible to prevent vibrations of the fixed scale 14 but also to regulate the traveling position of the guide rollers. The inner surface has a smooth finish. Damping material 20
is fixed to the entire area or part of the upper surface of the fixed scale 14 directly or via a vibration absorbing material such as rubber using an adhesive material, a screw, or the like. 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. A sleeve 23 is arranged between the slider 15 and one guide roller 17A (the one on the right side in FIG. 2), and the other guide roller 17
A spring 24 is disposed between B and B. spring 2
4 presses the side surfaces of each guide roller 17A, 17B against the inner surface of the protrusion of the damping material 20.

As shown in FIG. 3, the damping material 15 has a cutout hole 22 extending in the longitudinal direction of the fixed scale 14, and the upper surface of the fixed scale is exposed at this hole.
On the other hand, on the bottom surface of the optical unit 5, there are
As shown in FIG. 4, a convex portion 25 is provided at a position facing the notch hole 22 of the damping material 20 on the upper surface of the fixed scale 14. The convex portion 25 is formed such that its tip is positioned within the cutout hole 22 of the vibration damping material and is separated from the upper surface of the fixed scale by a predetermined minute distance. The convex portion 25 is the optical unit 5
It may be formed integrally with the lower surface of the holder or may be removable. Also, as shown in Figure 5,
The convex portion may be formed by a rotating member 25A such as a roller and a support plate 25B. In FIG. 1, reference numeral 26 denotes 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 holder 4,
The document 3 is irradiated with a fluorescent lamp 6, and the reflected light is changed to an optical path by a reflecting mirror 7 and placed on a reading element 9 by a condensing lens 8.
The reading element 9 is electronically main-scanned by the drive circuit 10, and processing such as photoelectric conversion is 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 convex portion 25 on the lower surface of the optical unit 5 travels within the cutout hole 22 and is slightly away from the upper surface of the fixed scale 14, so there is no problem with the traveling. If some external force is applied to the optical unit 5 and the slider 15 falls down from the bottom surface of the fixed scale 14, the optical unit 5 will also fall at the same time.
The lower end of the convex portion 25 immediately contacts the upper surface of the fixed scale to prevent it from falling, and then returns to its original position due to the absorbing force of the permanent magnet of the slider.

The distance between the convex portion 25 and the upper surface of the fixed scale 14 needs to be within a predetermined tolerance range. That is,
When the guide roller is in contact with the lower surface of the fixed scale, the convex portion 25 does not contact the fixed scale 14,
The value must be such that when the guide roller shaft separates from the lower surface of the fixed scale and the convex portion comes into contact with the upper surface of the fixed scale, it immediately returns to its original position due to the attractive force of the slider 15. This distance is determined from the reference plane (lower surface) of the optical unit 5, as shown in FIGS. 6 and 7.
Distance f from to the tip of the convex portion 25, fixed adapter 1
It is determined by the distance g to the center of the guide roller shaft support hole 8, the radius h of the guide rollers 17A and 17B, and the thickness i of the fixed scale 14. The processing accuracy of each of these parts is determined so that even if the respective errors are integrated, the distance between the convex portion 25 and the fixed scale 14 is within a predetermined tolerance range, and the parts are manufactured with that processing accuracy. There is. Therefore, by simply assembling each part, the distance between the convex portion 25 and the fixed scale 14 can be maintained within a predetermined tolerance, and there is no need for adjustment and attachment as in the conventional case.

Effects of the Invention As is clear from the above explanation, although the present invention uses a linear pulse motor with a damping material attached to the top surface of the fixed scale, the fixed scale is improved by providing a cutout hole in the damping material. The top surface is exposed, and the top surface and the protrusion provided on the bottom surface of the optical unit prevent it from falling, so by controlling the machining accuracy of the fixed scale and the protrusion, the distance between the protrusion and the fixed scale can be adjusted. It can be maintained within desired tolerances and requires no adjustment during assembly. As a result, the manufacturing process can be simplified and costs can be reduced. Furthermore, the slider can be replaced by simply removing the optical unit, which has the effect of greatly simplifying the work.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a driving device of a reading device according to an embodiment of the present invention, FIG. 2 is a front sectional view of a part thereof, and FIG. 3 is a diagram of a fixed scale and damping material used in this embodiment. 4 is a perspective view of the lower surface of the optical unit, FIG. 5 is a perspective view of the lower surface of the optical unit with a modified example of the convex portion, FIGS. 6 and 7 are illustrations of fall prevention distance tolerances, and FIG. Figure 8 is a schematic perspective view of a conventional linear pulse motor, Figure 9 is an explanatory diagram of its operation,
Fig. 10 is a schematic front view of a print head drive mechanism using a conventional linear pulse motor, and Fig. 11 is a schematic front view of a print head drive mechanism using a conventional linear pulse motor.
FIG. 2 is a plan view of a stopper portion of the mechanism shown in FIG. DESCRIPTION OF SYMBOLS 1... Document table, 2... Document table glass, 5... Optical unit, 11... Drive mechanism, 14... Fixed scale, 15... Slider, 16... Guide roller, 17, 17A, 17B... Guide Laura, 1
8... Fixed adapter, 20... Damping material, 22...
Notch hole, 25... convex part.

Claims (1)

[Scope of Claims] 1. A drive mechanism of a reading device that moves an optical unit that photoelectrically reads a document on a document table along the document table, the drive mechanism being a fixed device stationary and disposed below the optical unit. A linear pulse motor having a scale and a slider located on the lower surface side of the fixed scale and running on the lower surface of the fixed scale by a guide roller, and means for holding the optical unit on the slider of the linear pulse motor,
The linear pulse motor further includes a vibration damping member fixed to the entire surface or a part of the upper surface of the fixed scale and having a cutout hole extending in the longitudinal direction of the fixed scale, and the optical unit is fixed to the upper surface of the fixed scale. A driving device for a reading device, characterized in that the facing portion has a convex portion whose tip is located in the notch hole of the vibration damping material and is formed at a predetermined distance from the upper surface of the fixed scale. . 2. The driving device for a reading device according to claim 1, wherein the convex portion is made of a rotatable member.