JPH08248528A - Image reader - Google Patents

Abstract

PURPOSE: To suppress the occurrence of oscillation of a carriage in the reading operation of an original image, to speed up an image reading operation and to prevent the generation as far as possible by providing the image reader with the contact parts of the carriage and a wire at a specific number of points forward and backward in the moving direction of the carriage. CONSTITUTION: This image reader is provided with a pair of the contact parts 5, 5 for holding the wire 2 at the two points forward and backward of a fixing part 3 on the rear surface side of the carriage 1. The respective contact parts 5 have a pair of holding pieces 11, 12 formed by bending sheet metals constituting the carriage. The wire 2 is held and fixed between these holding pieces 11 and 12. The contact parts 5 press the wire 2 along the oscillation direction of the carriage 1 when the oscillation occurs in the carriage 1 of such constitution but the wire 2 is held extended along the moving direction of the carriage 1 and, therefore, the contact parts 5 eventually receive the reaction in the oscillation direction of the carriage 1 and the oscillation of the carriage 1 is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus which moves a carriage on which a lamp is mounted along a lower surface of a platen and scans an original image on the platen while exposing it in a slit shape. The present invention relates to improvement of an engagement state between a carriage and a wire wound along a moving direction of the carriage.

[0002]

2. Description of the Related Art An image reading apparatus having a slit exposure optical system of this type is provided with a carriage on which a lamp and a reflecting plate for condensing the illumination light of the lamp in a slit shape are mounted. The document image placed on the platen is exposed and scanned while being moved along the lower surface side, and the reflected light is guided to the photoconductor drum or the light detection sensor via the mirror and the lens.

FIG. 9 shows a conventional carriage. In the figure, reference numeral 50 is a carriage, reference numeral 51 is a lamp, reference numeral 52 is a reflecting plate, and reference numeral 53 is a mirror for guiding reflected light to a photosensitive drum. , 54 are lamp holders, respectively. On the bottom surface of the carriage 50, a resin pad 56 that constitutes a slide bearing together with a rail 55 is attached, while a fixing portion 58 that sandwiches a wire 57 wound by a motor (not shown) is provided. The carriage 50 slides on the rail 55 at a predetermined speed according to the winding speed of the wire 57. In addition, as shown in FIG. 10, the fixed portion 58 has the wire 57 only at one position along the moving direction of the carriage 50.
Is engaged with.

FIG. 11 is a diagram showing the moving speed of the carriage in an actual image reading operation. When the operation of reading the original image starts, first the carriage starts sliding from the home position and a predetermined reading speed V
_{When the} scanning speed is accelerated to _F (time area a in the drawing) and the reading speed V _F is reached, the exposure scanning of the original image is performed at the speed (time areas b and c). Then, is decelerated with exposure scanning of the original image is completed and stopped (time domain d), in turn it is accelerated to start the slide toward the home position to a predetermined return speed V _R (time domain e), according return After sliding for a while at the speed V _R (time regions f and g), it is decelerated so as to stop at the home position and one scan of the document image ends (time region h). Further, when the original image is continuously scanned, the same operation is repeated again with a predetermined pause time i.

Further, FIG. 12 is a diagram simply showing the posture of the carriage in each time region in FIG. 11, and in each of the minute diagrams, the right side of the drawing is the reading direction of the original image. When the carriage 50 accelerates to the reading speed V _F in the time region a, the leading end of the carriage 50 in the traveling direction tends to be lifted from the rail 55 according to the law of inertia (FIG. 1).
2 (a)). For this reason, when the carriage 50 reaches the reading speed V _F and the acceleration is completed, the rear end of the carriage 50 in the traveling direction floats up from the rail 55, and the swing-back is likely to occur, reaching the reading speed V _F. During a later period (that is, the time region b), a swinging phenomenon occurs in which the carriage 50 swings back and forth in the traveling direction (see FIG. 12B). Even if the carriage 50 slides at the reading speed V _F , the original image cannot be read while the swinging phenomenon occurs, so normally, the original image is limited to the time region c in which the phenomenon is suppressed. Is being read (see FIG. 12C).

Further, in the time domain d, the carriage 50
When is decelerated from the reading speed V _{F, the} trailing end of the carriage 50 in the traveling direction tends to lift up from the rail 55 (see FIG. 12D), and the carriage 50 accelerates toward the home position in the time region e. When started, this state becomes more prominent (see Fig. 12 (e)). Therefore, when the carriage 50 reaches the return speed V _R and its acceleration is completed, the above-described swinging phenomenon occurs (see FIG. 12 (f)), and this swinging phenomenon is larger than that occurring in the time region b. And the carriage 50
It is accompanied by noise caused by the collision between the resin pad 56 and the rail 55. Since the swinging phenomenon here subsides after a while, the carriage 50 in the time region g stably glides at the return velocity V _R (see FIG. 12 (g)).

However, when the vehicle decelerates in the time region h to stop at the home position, the trailing end of the carriage 50 in the traveling direction tends to be lifted from the rail 55 (see FIG. 12 (h)) and temporarily stops at the home position. A swinging phenomenon occurs in the carriage 50 (see FIG. 12 (i)). If the pause time i is sufficiently long, the swinging phenomenon is subdued by the time when the reading operation of the next original image is started, but if the pause time i is short, the carriage in the time region a ′ is reduced. The posture of the carriage 50 is affected by the swinging phenomenon in the time region i, and depending on the timing when the carriage 50 starts accelerating to the reading speed V _F , the leading end of the carriage 50 in the traveling direction is more than in the time region a. It rises greatly (see FIG. 12 (a)).

[0008]

By the way, in the conventional image reading apparatus configured as described above, in order to reduce the time required for one scanning of the document image, after the carriage reaches the reading speed V _F. It is necessary to read the document image promptly. However, since the reading of the original image cannot be performed within the time region b in FIG. 11 in which the swing phenomenon occurs, the time region b must be shortened in order to shorten one scanning time of the original image. Was needed.

Further, in the case of continuously scanning the original image, the overall scanning time can be shortened by shortening the carriage pause time i after one scan is completed. If is set to be short, the scanning of the next document image is started before the carriage swing phenomenon is completely settled, which may adversely affect the reading of the document image.

Further, in order to reduce the time required for one scanning of the original image, it is sufficient to set a large acceleration or deceleration of the carriage or a return speed V _R. However, in such a setting, the neck of the carriage is Since the swing phenomenon becomes remarkable, there is also a problem that a large noise is generated in the time regions b, f and i.

To solve such a problem, conventionally, a leaf spring for sandwiching the rail together with the resin pad is provided on the carriage to take measures to prevent the carriage from floating from the rail during acceleration / deceleration. However, if the rail is sandwiched between the resin pad and the leaf spring in this way, the frictional resistance during movement of the carriage increases, and a new problem arises in that the motor for winding the wire needs to be powered up. Oops.

As another measure, as shown in FIG. 13, the wire 57 for driving the carriage 50 is fixed to the fixing portion 5.
There is also proposed a method in which the carriage is lifted from the rail by applying tension to pull the carriage 50 downward to the wire 57 by stretching it with 8 as the apex (Japanese Patent Publication No. 19936/1990). Publication, JP-A-5
-19372). However, even in this proposal, the frictional resistance during the movement of the carriage increases, and particularly when the carriage is located at the home position or the end portion in the reading direction, the tension that pulls the carriage downward in the carriage increases, so that the torque is increased. There is also a problem that the motor goes out of step due to a shortage. Also, since the wire is stretched diagonally with respect to the moving direction of the carriage,
Since the winding amount of the wire by the motor and the moving amount of the carriage are slightly different and the moving speed of the carriage is also slightly changed, there is also a problem that the reading magnification of the original image is partially different.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of the swinging phenomenon of the carriage during the reading operation of the original image and to increase the speed of the reading operation of the original image. It is an object of the present invention to provide an image reading apparatus that can be realized and can prevent noise generation as much as possible.

[0014]

In order to achieve the above object, the image reading device of the present invention is connected to a wire,
In an image reading apparatus including a carriage that scans a document on a platen in conjunction with the wire, contact portions of the carriage and the wire are provided at at least two positions in front and behind in a moving direction of the carriage. To do.

In such a technical means, the abutting portion may be one that simply contacts the wire from above, or one that holds the wire. Moreover, you may utilize the fixing part of a wire as this contact part.

[0016]

According to the above technical means, the carriage is provided with abutting portions at at least two front and rear positions in the moving direction, and the abutting portions are attached to the wire stretched along the moving direction of the carriage. Since they are in contact with each other, when a swinging phenomenon occurs in the carriage, the reaction force of the force that the contact portion presses the wire acts on the contact portion from the wire, and the action direction is always the shaking of the carriage. Since it is in the opposite direction to the moving direction, the carriage swinging phenomenon is suppressed, and even if a severe swinging phenomenon occurs, this can be quickly eliminated.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The image reading apparatus of the present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 show a first embodiment of the present invention. Reference numeral 1 denotes a carriage, and reference numeral 2 denotes a wire wound by a motor (not shown). A fixing portion 3 is provided on the lower surface side of the carriage 1, and the wire 2 is clamped and fixed to the fixing portion 3 by a screw 4 screwed into the fixing portion 3.
In addition, a pair of abutting portions 5 and 5 for holding the wire 2 are provided at two positions before and after the fixed portion 3 on the lower surface side of the carriage 1.
Is provided. Each abutting portion 5 has a pair of sandwiching pieces 11 and 12 formed by bending a metal plate forming a carriage, and the wire 2 is sandwiched and fixed between the sandwiching pieces 11 and 12. . 1 and 3, the rails and the resin pads that support the sliding of the carriage are not shown for simplicity.

According to the image reading apparatus of this embodiment constructed as described above, as shown in FIG.
When the head swing phenomenon occurs, the contact portion 5 presses the wire 2 along the swinging direction (solid arrow) of the carriage 1, but the wire 2 is stretched along the moving direction of the carriage. Therefore, the contact portion 5 receives a reaction force from the wire in a direction (dotted line arrow) opposite to the swinging direction of the carriage 1, and swinging of the carriage can be suppressed.

Therefore, the swinging phenomenon of the carriage can be eliminated quickly, and it is possible to prevent the noise from being generated by the collision of the rail (not shown) and the resin pad.

On the other hand, FIG. 4 shows a second embodiment of the present invention. In this embodiment, a fixing portion 6 having the same structure as that of the first embodiment is provided at one end in the moving direction of the carriage 1 (that is, a direction in which the wire 2 is stretched), and a contact portion 7 having the same structure as that of the first embodiment is provided in the carriage. 1 is provided at the other end in the moving direction.
That is, in the present embodiment, the fixing portion 6 also functions as one of the two contact portions of the present invention, and the same effect as that of the first embodiment with a simpler structure than the first embodiment. Is what you can get.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, fixing portions 8 having the same structure as in the first embodiment are provided at two positions before and after in the moving direction of the carriage 1 (that is, the direction in which the wire 2 is stretched), and these fixing portions 8 and 8 are abutting portions of the present invention. Is functioning as. Therefore, it is possible to obtain the same effect as that of the first embodiment with a simpler structure than that of the second embodiment.

Further, FIGS. 6 and 7 show a fourth embodiment of the present invention. A fixing portion 9 having the same structure as that of the first embodiment is provided on the lower surface side of the carriage 1, and a pair of abutting pieces 10 and 10 formed by bending a metal plate constituting the carriage 1 are provided at two front and rear portions of the fixing portion 3. Are provided, and these contact pieces 10 are in contact with the wire 2 from above.

As described above, even if the contact pieces 10 and 10 simply contact the wire 2 from above, as shown in FIG. Abutting piece 10 along the swinging direction of (solid arrow)
When the wire 2 presses the wire 2, the contact piece 10 receives the reaction force from the wire 2 in the direction opposite to the swing direction of the carriage 1 (broken line arrow), so that the swing of the carriage is suppressed as in the first embodiment. You can

[0024]

As described above, according to the image reading apparatus of the present invention, when the carriage swings, the reaction force of the contact portion pressing the wire is always in the direction opposite to the swing direction of the carriage. Since it acts on the carriage as described above, it is possible to effectively suppress the occurrence of the swinging phenomenon of the carriage in the reading operation of the original image, and it is possible to speed up the reading operation of the original image. In addition, it is possible to prevent the generation of noise as much as possible.

Further, since the force pressing the carriage against the rail does not act on the carriage, it is possible to suppress the occurrence of the swinging phenomenon while preventing an increase in the movement resistance of the carriage.

[Brief description of drawings]

FIG. 1 is a front view showing a carriage according to a first embodiment of an image reading apparatus of the present invention.

FIG. 2 is a perspective view showing a carriage according to the first embodiment.

FIG. 3 is a front view showing a state in which a head swing phenomenon has occurred in the carriage according to the first embodiment.

FIG. 4 is a front view showing a carriage according to a second embodiment of the image reading apparatus of the present invention.

FIG. 5 is a front view showing a carriage according to a third embodiment of the image reading apparatus of the present invention.

FIG. 6 is a front view showing a carriage according to a fourth embodiment of the image reading apparatus of the present invention.

FIG. 7 is a perspective view showing a carriage according to a fourth embodiment.

FIG. 8 is a front view showing a state in which a head swing phenomenon has occurred in a carriage according to a fourth embodiment.

FIG. 9 is an enlarged view of a main part showing a carriage of a conventional image reading device.

10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a graph showing the movement of the carriage of the image reading device.

FIG. 12 shows the posture of the carriage during operation.
It is the figure shown corresponding to.

FIG. 13 is a front view illustrating an example of a method of preventing the carriage from swinging in a conventional image reading apparatus.

[Explanation of symbols]

 1 ... Carriage, 2 ... Wire, 3 ... Fixed part, 5 ... Abutting part

Claims (1)

[Claims] 1. An image reading apparatus including a carriage which is connected to a wire and which scans a document on a platen in conjunction with the wire, wherein at least two of front and rear in a moving direction of the carriage are provided.
An image reading apparatus characterized in that a contact portion between the carriage and the wire is provided at a position.