JPH0815786A - Original exposing scanning device - Google Patents

Abstract

PURPOSE:To make a carriage run in a stable state while preventing the carriage from stepping out, as for an original exposing scanning device for moving the carriage with a mounted exposing means by a stepping motor. CONSTITUTION:A fly-wheel 14 is loaded on a supporting shaft 11 in a rotary driving system for driving the carriage through a one-way clutch 13. An outer shell 15a for a torque limiter 15 is firmly fixed on the fly-wheel 14, and an internal core 15b is supported so as not to be rotated. By having such a constitution, a rotary driving force is transmitted to the fly-wheel 14 from the supporting shaft 11 through the one-way clutch 13 at the time of exposing and scanning, then, a rotary inertial force is increased, and also, the rotary torque of the torque limiter 15 becomes a rotary load of the fly-wheel 14, and the fly-wheel 14 and the supporting shaft 11 are smoothly rotated in one body. And also, at the time of backward running after scanning, the driving force is interrupted by the one-way clutch 13, the inertia of the rotary driving system is not increased, then, the device is driven with a good start and at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document exposure scanning device used in a copying machine, an image scanner, etc., for scanning a document surface by moving a carriage equipped with an exposure means.

[0002]

2. Description of the Related Art As an original exposure scanning device used in a copying machine, an image scanner, etc., the driving force of a motor is transmitted to a carriage via a belt or a cable so that the carriage runs along the original surface and is mounted on the carriage. It is well known that a document surface is exposed and scanned by the exposure means. In a digital copying machine or the like, the obtained reflected light (image light) is directly or reflected by a mirror and guided to an image sensor, and in an analog copying machine or the like, it is guided to a photoconductor. Further, after the exposure scanning for one document is completed, the carriage is moved at a high speed to the exposure scanning start position,
The exposure scanning of a continuous document can be efficiently performed.

A stepping motor is widely used as a motor for supplying a driving force to the carriage.
With the stepping motor, the amount of rotation and the rotation speed can be accurately controlled by the input pulse, and it is easy to change the traveling speed of the carriage according to the reading magnification and between the exposure scan and the return scan. . However, since the output torque of the stepping motor periodically fluctuates according to the cycle of the input pulse, minute unevenness of the rotation speed occurs in the traveling of the carriage. Therefore, by attaching a rotary inertia body to the drive shaft of the stepping motor or the rotary shaft of the driving force transmission means to increase the inertial force, uneven rotation of the stepping motor or the like is reduced, the carriage travels stably, and the original image This prevents a decrease in reading accuracy or exposure scanning accuracy. As described above, when the inertia of the rotary drive system is increased by the rotary inertia body, the rotation of the stepping motor is stabilized, but the rise in the case of rotating the stepping motor at a high speed is deteriorated. For this reason, the stepping motor is overloaded, and the traveling operation of the carriage does not match the predetermined range and the predetermined position, so-called step-out occurs.

In order to prevent such a step-out, a technique disclosed in JP-A-2-306232 or a technique disclosed in JP-A-3-214862 has been proposed. The technique described in Japanese Patent Laid-Open No. 2-306232 is
By fixing the flange made of magnetic material to the drive shaft of the motor,
A rotary inertia body composed of a magnet net is supported so as to be rotatable relative to a flange, and the rotary inertia body is attracted to the flange via a sliding member. In this conventional technique, the attraction force between the flange and the rotary inertia body is reduced by the sliding member, and during rapid acceleration, the flange overcomes the attraction force with the rotary inertia body and rotates. Therefore, the inertia of the rotary drive system does not become excessive at the time of return scanning, and the occurrence of step-out can be avoided.

In the technique disclosed in Japanese Patent Laid-Open No. 3-214862, a rotary inertia body is attached to a drive shaft of a stepping motor or a rotary shaft of a driving force transmission means via an electromagnetic clutch, and the electromagnetic clutch is controlled. By doing so, the drive shaft of the stepping motor and the rotary inertia body are separated from each other during the return scanning, and the inertia of the drive system is not increased.

[0006]

However, the above-mentioned prior art has the following problems. JP-A-2-30623
In the technique described in Japanese Patent No. 2 publication, the flange rotates idly when the acceleration of the stepping motor is large and the rotary inertia body does not rotate integrally. Therefore, when the exposure scanning is performed at high speed, the frequency of the input pulse is The acceleration of the rotation unevenness becomes too large and the rotation unevenness of the motor etc. is not reduced. Therefore, the selection range of the reading magnification and the speedup of the exposure scanning are limited. In the technique described in Japanese Patent Laid-Open No. 3-214862, since the electromagnetic clutch is controlled to be turned on / off by the speed at the time of exposure scanning and the exposure scanning / return scanning, the control becomes complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to make a carriage stably run at a wide range of exposure scanning speeds without causing complicated control, and to perform step out. An object of the present invention is to provide an original document exposure scanning device.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to a carriage which is equipped with a document exposing means and which is supported so as to be able to move and face the surface of a document, and the carriage is moved. In a document reading apparatus having a stepping motor for applying a driving force for moving and a transmission means for transmitting the driving force from the stepping motor to the carriage, one of a drive shaft of the stepping motor or a rotation shaft of the transmission means is provided. It is assumed to have a rotary inertia body mounted via a directional clutch, and load generating means for applying a substantially constant rotational load to the rotary inertia body when the rotary inertia body rotates at a substantially constant speed.

The above stepping motor can apply driving force in two kinds of forward and reverse directions by switching the rotation direction. The one-way clutch transmits the rotational force in the rotation direction of the drive shaft of the stepping motor or the support shaft driven by the stepping motor to the rotary inertia member during the exposure scanning, and the drive shaft during the return scanning in which the rotation direction is reversed. The rotational force of the support shaft is not transmitted to the rotary inertia body.

Further, the load generating means applies a rotational load such as a frictional force to the rotary inertia body. For example, the inner core is supported so as not to rotate, and the outer shell is coaxially fixed to the rotary inertia body. A torque limiter or the like can be used.

[0011]

In the document reading apparatus of the present invention, during the exposure scanning, the driving force of the stepping motor is transmitted from the driving shaft of the stepping motor or the rotation shaft of the transmission means to the rotary inertia body via the one-way clutch, and the rotary inertia body is transmitted. Rotates. A substantially constant rotational load is applied to the rotary inertia body from the load generating means. Therefore, the above-mentioned load acts on the engaging portion of the one-way clutch to firmly engage the one-way clutch. Therefore, even if there is unevenness in the rotational driving force of the drive shaft, the rotary inertia body and the drive shaft etc. rotate integrally without different behavior at the engaging portion of the one-way clutch. Further, the unevenness of the rotation driving force of the stepping motor is leveled by the inertial force of the rotating inertial body, and the stepping motor smoothly rotates at a constant speed, so that the unevenness of the rotation speed does not occur.

When the exposure scanning of one document is completed and the stepping motor starts rotating at a high speed in the direction opposite to that during the exposure scanning, the drive shaft of the stepping motor and the support shaft of the transmission means also rotate in the opposite direction. This rotational force is blocked by the one-way clutch portion and is not transmitted to the rotary inertia body. Therefore, the inertia of the stepping motor or the like is not increased by the rotating inertial body, and the stepping motor or the like starts to rotate well.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a document exposure scanning device according to the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic plan view and a schematic side view showing an original exposure scanning device according to an embodiment of the present invention.

The document exposure / scanning apparatus of this embodiment includes a platen glass 1 on which a document is placed, and the platen glass 1
A lamp carriage 4 which is movably supported along with the exposure lamp 2 and the first mirror 3, and a second carriage 5 and a third mirror which are movably supported in the same direction as the lamp carriage 4. 6, a mirror carriage 7 on which the image pickup device 6 is mounted, an image sensor 8 that detects reflected light (image light) of the light emitted from the exposure device 2 to the document, and a lamp carriage 4.
And a capstan dolly 10 for driving the mirror carriage 7 via a cable 9, a support shaft 11 for supporting the capstan dolly 10, and a stepping motor 12 for applying a rotational driving force to the support shaft 11. . In addition, as shown in FIG. 2, a flywheel (rotational inertial body) 14 mounted on one end of the support shaft 11 via a one-way clutch 13 and an outer shell 15 a are coaxially fixed to the flywheel 14. It has a torque limiter and 15. The inner core 15b of the torque limiter 15 has a fixed pin 1
It is supported by 6 so as not to rotate, and a friction sliding member 15c is provided between the outer shell 15a and the inner core 15b of the torque limiter 15.

A part of the lamp carriage 4 is fixed to a cable 9 and is driven by a capstry 10 via the cable 9 to reciprocate. Further, at the time of forward movement (when moving in the direction of arrow C shown in FIG. 1), the exposure lamp 2 is turned on to irradiate the original surface with light, and the obtained reflected light (image light) is reflected by the first mirror 3. And is guided to the second mirror 5 of the mirror carriage 7. When the reading is completed, the exposure lamp 2 is turned off.

The mirror carriage 7 sequentially reflects the image light guided from the first mirror 3 of the lamp carriage 4 to the second mirror 5 and the third mirror 6 and guides it to the image sensor 8. Has become. The mirror carriage 7 includes a small pulley 17a and a small pulley 17a that are rotatably attached.
7b and the cable 9 is connected to the small pulleys 17a, 17
The mirror carriage 7 is reciprocally driven in the same direction as the lamp carriage 4 by a capstry 10 via a cable 9 by being hung on b. At this time, the small pulleys 17a and 17b play the role of a moving pulley, and the mirror carriage 7 is 1 / of the lamp carriage 4.
It is driven at a speed of 2 so that the image light always reaches the image sensor 8 with a constant optical path length.

During the exposure scanning, the stepping motor 12 receives a pulse having a frequency corresponding to the scanning speed, rotates at a predetermined speed, and drives the support shaft 11 via the drive belt 18. . Further, during return scanning, a pulse is input so as to rotate at a high speed in the direction opposite to that during exposure scanning. The one-way clutch 13 transmits the rotational force in the direction in which the support shaft 11 is rotationally driven during exposure scanning (the direction indicated by arrow A in FIG. 1) to the flywheel 14, and the rotational direction of the support shaft 11 during return scanning. The rotational force (in the direction indicated by arrow B in FIG. 1) is not transmitted.

In the present embodiment having the above-described structure, during the exposure scanning, the stepping motor 12 receives a pulse corresponding to the scanning speed, rotates at a predetermined speed corresponding to the reading magnification, and the support shaft 11 is rotated as shown in FIG. Rotate in the clockwise direction (arrow A direction in the figure). Then, the rotational force of the support shaft 11 is transmitted to the flywheel 14 via the one-way clutch 13, and the flywheel 14 also rotates in the clockwise direction in the figure.
At the same time, the torque limiter 15 fixed to the flywheel 14 also rotates. At this time, the torque limiter 15
Since the inner core 15b is constrained from rotating by a fixed shaft, a frictional force is generated in the friction sliding member 15c interposed between the inner core 15b and the outer shell 15a, which causes a rotational load of the flywheel 14. To work. As a result, flywheel 1
Reference numeral 4 constrains relative rotation with respect to the support shaft 11, and always rotates integrally with the support shaft 11. Therefore, the support shaft 11 and the stepping motor 1 are controlled by the flywheel 14.
The state in which the inertia of 2 is increased is continuously maintained, and the support shaft 11 and the stepping motor 12 rotate at a constant speed.

When the support shaft 11 rotates in the clockwise direction in the figure (direction of arrow A in the figure) at a constant speed, the capstry 10 also rotates in the clockwise direction in the figure (direction of the arrow A in the figure) at a constant speed. Therefore, the lamp carriage 4 moves at a constant speed in the direction of arrow C in the figure via the cable 9. At this time, the exposure lamp 2 mounted on the lamp carriage 4 irradiates the original surface with light, and the obtained image light is emitted from the first mirror 3
And is guided to the mirror carriage 7. In addition, the mirror carriage 7 is moved in the direction of arrow C in the figure at a speed half that of the lamp carriage 4 via the cable 9, and at the same time, the image light reflected and guided by the first mirror 3 is transmitted. The light is sequentially reflected by the second mirror 5 and the third mirror 6 and is incident on the image sensor 8.

When the exposure scanning is completed, the lamp (not shown) of the exposure device 2 is turned off and the stepping motor 12 is turned off.
Starts rotating at a high speed in the counterclockwise direction in the figure (direction of arrow B in the figure). Then, the support shaft 11 also starts rotating in the counterclockwise direction in the figure (direction of arrow B in the figure). However, one-way clutch 1
3 does not transmit the rotational force in this direction, the support shaft 11
Is not transmitted to the flywheel 14, and the inertia of the support shaft 11 and the stepping motor 12 is not increased. Therefore, the support shaft 11 and the stepping motor 12 start up well and start rotating at high speed. When the support shaft 11 rotates in the counterclockwise direction in the drawing (direction of arrow B in the drawing) at a high speed, the lamp carriage 4 and the mirror carriage 7 move at a high speed by an operation opposite to that in the exposure scanning, and the scanning start position is immediately started. Return to.

As described above, according to this embodiment, by mounting the one-way clutch 13 between the flywheel 14 and the support shaft 11, the flywheel 14 does not interlock with the support shaft 11 during the return scanning. As a result, the inertia of the stepping motor 12 and the support shaft 11 is not increased during the return scanning, the stepping motor 12 and the support shaft can be rotated at a high speed with good rising, and the step-out does not occur during the return scanning.

The flywheel 14 is attached to the support shaft 11, the outer shell 15a of the torque limiter 15 is attached to the center of the flywheel 14, and the inner core 15b is supported by the fixed shaft 16 to restrain the rotation. By applying a load to the rotation of the flywheel 14 by the friction generated between the outer shell 15a and the inner core 15b of the torque limiter 15, the relative rotation of the flywheel 14 with respect to the support shaft 11 is restricted during the exposure scanning, The flywheel 14 can be rotated integrally with the support shaft 11. As a result, the state where the inertia of the stepping motor 12 and the support shaft 11 is increased can be maintained, and the support shaft 11 and the stepping motor 12 can be rotated at a constant speed without uneven rotation.

In this embodiment, the torque limiter 15
The outer shell 15a of the above is coaxially fixed to the flywheel 14,
In addition, although the rotational load is applied to the flywheel 14 by restraining the rotation of the inner core 15b, the load generating means is not limited to the one described above, and, for example, a friction member is pressed against the flywheel from the outside. You may. Further, the flywheel 14 may be attached to the drive shaft of the stepping motor 12 instead of being attached to the support shaft 11. Further, in the present embodiment, the lamp carriage 4 and the mirror carriage 7 are driven by the double-sided driving method, but the present invention can be applied to a single-sided driving type document exposure scanning apparatus. The present invention can also be applied to an analog type original document exposure scanning device.

[0024]

As described above, in the document reading apparatus according to the present invention, by mounting the one-way clutch between the rotary inertia body and the drive shaft or the support shaft, the rotary inertia body and the drive shaft are driven during the return scanning. The shaft or support shaft will not work together. Therefore, without performing any special control, the stepping motor or the like can be started and speeded up well at the time of the return scanning, and step-out can be prevented.

A rotary inertia body is attached to the drive shaft of the stepping motor or the support shaft of the transmission means.
By applying a load to the rotation of the rotary inertia body, restraining the relative rotation of the rotary inertia body with respect to the drive shaft or the support shaft during exposure scanning, and rotating the rotary inertia body integrally with the drive shaft or the support shaft. You can Therefore, regardless of whether it is during high-speed exposure scanning, always maintain the inertia of the support shaft or stepping motor increased during exposure scanning, and rotate the support shaft or stepping motor at a constant speed. You can

[Brief description of drawings]

FIG. 1 is a schematic plan view and a schematic side view showing a document exposure scanning device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part of the embodiment shown in FIG.

[Explanation of symbols]

 1 Platen Glass 2 Exposure Lamp 3 First Mirror 4 Lamp Carriage 5 Second Mirror 6 Third Mirror 7 Mirror Carriage 8 Image Sensor 9 Cable 10 Capstan Cooley 11 Support Shaft 12 Stepping Motor 13 One-way Clutch 14 Flywheel 15 Torque limiter

Claims (1)

[Claims] 1. A carriage having document exposing means mounted thereon, which is supported so as to be able to move and face the document surface, a stepping motor which gives a driving force for the carriage to move, and a stepping motor from the stepping motor. A document reading apparatus having a transmission means for transmitting the driving force to the carriage, comprising: a rotary inertia body mounted on a drive shaft of the stepping motor or a rotation shaft of the transmission means via a one-way clutch; and the rotary inertia body. And a load generating means for applying a substantially constant rotational load to the rotary inertia member when the document rotates at a substantially constant speed.