JPH04366940A - Optical carriage - Google Patents

Abstract

PURPOSE:To obtain an easy means which reduces the load on a driving device and makes the optical carriage stationary at its home position securely in safety by constituting a guide whose guide path varies so that the perpendicular height of the optical carriage increases. CONSTITUTION:Guides 3A and 3B of a 1st optical carriage 1 have movable parts which are guided by a rail 9, the movable parts can freely be guided and slid at right angles to a base part, and rolls 10 are provided under the movable parts and rolled on the rail 9. When the rolls 10 are rolled on the rail 9, part or the whole of the optical carriage 1 moves up as the rolls 10 move up and position energy increase as the upward movement to brake the optical carriage 1. When the rolls 10 are rolled down on the rail 9, part or the whole of the optical carriage 1 moves down as the rolls 10 move down and the position energy decreases according to the downward movement to assist the driving of the optical carriage 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical carriage used for reading originals in an image forming apparatus.

0002

[Prior Art] Used in a document reading section of an image forming apparatus,
There is an optical carriage that is guided along a guide and reciprocates from a home position when scanning a document. In a copying machine having such an optical carriage, in order to increase the number of copies per unit time (usually per minute, CPM), the speed of the return movement from the end of exposure to the home position should be reduced as much as possible. It is desirable to raise it. However, as the return speed increases, it becomes more difficult to reliably keep the optical carriage stationary at the home position.

[0003] For this reason, in an optical carriage used in a document reading section of an image forming apparatus, which moves back and forth when scanning a document,
The following technology is disclosed. (2) An optical carriage that locks the optical carriage by abutting it against a stopper to improve positioning accuracy at the home position (see Japanese Patent Laid-Open No. 1-237570). (1) A device that increases positioning accuracy by controlling the braking time according to the moving speed of the carriage (see Japanese Patent Application Laid-Open No. 1983-509).

[0004] A compression spring is provided between the first and second scanners, and the spring is compressed at the end of the movement to absorb impact force (see Japanese Patent Publication No. 1-4506).

[0005]

[Problem to be Solved by the Invention] However, in the technique (2) above, it is expected that an impact force will be applied when the carriage hits the stopper. Therefore, it is necessary to sufficiently reduce the speed of the optical carriage before the stop position. For this purpose, as shown in item (2) above, it is necessary to appropriately control the drive device for the optical carriage. However, since the high-speed carriage is suddenly decelerated, it is conceivable that a load will be placed on the drive device. In addition, the above-mentioned item (2) involves a method of weakening the impact force at the time of stopping, but considering the limitations of the shock absorbing device, it would be difficult to realize this in a high-speed copying machine.

[0006] As described above, it is difficult with the prior art to reliably and safely stop an optical carriage moving at high speed at the home position, and there is a need for an auxiliary drive means independent of the conventional drive system. SUMMARY OF THE INVENTION An object of the present invention is to provide a simple means for safely and reliably stopping an optical carriage at a home position while reducing the burden on the drive device.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a guide that increases the height of the optical carriage in the vertical direction in a range near the home position as the optical carriage approaches the home position during backward movement. The guide route is configured so that it changes as the distance increases.

[0008] Here, the guide may be a rail curved near the home position, and the rollers provided on the optical carriage may roll on this rail.

[0009] Also, the optical carriage is provided with a rolling element that is provided with a braking force during rotation, and the rolling element contacts this rolling element over a range near the home position, at least when the optical carriage approaches the home position. It is advantageous to provide a contact member that can be placed in a rotating state.

[0010] Here, the contact member is inclined to gradually push the bracket as the optical carriage approaches the home position during backward movement, and the rolling means engages with the shaft of the optical carriage to move the bracket forward and backward. a biasing means which is freely provided on the bracket and which biases the rolling means in the direction of pressing the contact member; It is also possible to have a locking means for locking the bracket at a certain position, and a release means for releasing the locking during the forward movement of the optical carriage.

[0011]

[Operation] A braking force is applied to the optical carriage in accordance with the degree of rise of the guide path of the contact member or in accordance with the braking force applied to the rolling means.

0012

【Example】

Example 1 (see FIGS. 1 to 3 and 9) This example corresponds to claims 1 and 2. First, the entire drive system of the optical carriage will be explained. In FIG. 9, which shows a general optical scanning system of a copying machine, two optical carriages, a first optical carriage 1 and a second optical carriage 2, are provided. , 3B to reciprocate. Each optical carriage is slidably fitted to the guide 3A, and rollers roll to the guide 3B.

A drive motor 4 constituting a drive device drives these optical carriages, and one end of a wire W is fixed to a pulley provided on its rotating shaft. The other end side of this wire W passes through the pulley P1 and connects to the first
It is semi-wound around the pulley P2 of the optical carriage and is fixed to a stationary member. A first optical carriage 1 is fixed in the middle of the wire W.

[0014] Depending on the manner in which the wire W is routed,
As the wire W is wound up by the drive motor 4, each optical carriage reciprocates on the guide, and satisfies the necessary conditions for scanning the document and forming an image on the photoreceptor. The first optical carriage 1 and the second optical carriage 2 are operated in conjunction. From this, it can be said that the object of the present invention can be achieved by controlling either one of the optical carriages. Therefore, the following example will be described as an example in which measures are taken for the first optical carriage 1. Note that both the first and second optical carriages have a common configuration, and as shown in FIG.
Consists of etc.

The basic idea of this example is schematically shown in FIG.
It is as shown in . In other words, the first optical carriage 1 must reach a predetermined speed (exposure speed) before the exposure start point (region (a) in FIG. 3), and must reach a predetermined speed (exposure speed) before the exposure start point (region (a) in FIG. 3). After exposure is completed (areas (b) and (c) in Figure 3), it is necessary to return to the home position as fast as possible.As is clear here, the maximum speed must be maintained for as long as possible. It is desirable to shorten the deceleration time. Conventionally, this placed a burden on the drive system, but in this example, the following means are used to assist the drive and reduce the burden on the drive system.

To explain the concept of this example with reference to FIG. 1, at the home position where the first optical carriage 1 is at the position shown by the solid line (at the end of the backward movement = at the start of exposure), the first optical carriage 1 is Place all (or some) of them in a high position. At the start of exposure, the optical carriage 1 goes down a slope to obtain potential energy to assist in driving, and at the end of the return, as it climbs up a slope, energy is taken away and deceleration is assisted.

Therefore, as shown in FIG. 1, as far as the first optical carriage 1 is concerned, the guide 3 shown in FIG.
A guide by a rail 9 is provided in addition to A and 3B. This rail 9 is configured such that the guide path changes in a range near the home position so that the height of the optical carriage in the vertical direction increases as the optical carriage approaches the home position during backward movement.

The first optical carriage 1 includes a guide 3A,
In addition to the base portion guided by the base portion 3B, there is a movable portion guided by the rail 9, and this movable portion is slidably guided in the vertical direction with respect to the base portion. and,
A roller 10 is provided at the bottom of this movable part, and it rolls on the rail 9. Alternatively, as far as the first optical carriage 1 is concerned, the guide 3A shown in FIG.
, 3B may be replaced with a rail 9, and the rollers 10 may roll.

In FIG. 1, the rail 9 is curved upward near the home position, and this region is shown in FIGS.
c) Corresponds to part. The right end position of this area corresponds to the home position, which is the position when the first optical carriage 1 starts forward movement for scanning, and corresponds to the position marked with ■ in FIG. 3. As the movable part, a relatively heavy fluorescent lamp 5 is used.
A further explanation will be added regarding the case where the movement moves up and down.

Now, the weight of the first optical carriage 1 as a whole is 1000 grams, the weight of the fluorescent lamp 5 including the attached elements that are in direct contact with the fluorescent lamp is 300 grams, and the maximum speed during return movement is 3 m.
/sec, energy of E=1/2×1×32=4.5J is required to keep this optical carriage stationary. As shown in the figure, if the fluorescent lamp moves upward by about 50 mm during the backward movement, the increase in potential energy E(H) due to the upward movement is E(H) = 1 x 9.
8×50×10×1/103=0.49J.

Therefore, according to this example, about 11% of the energy required to keep the optical carriage stationary can be obtained, and the load on the drive system can be reduced. During this process, the fluorescent lamp moves up and down and the roller 10 curves upward into the rail 9.
run on top of Note that by providing a member that abuts the first optical carriage 1 at the home position, the optical carriage can be stopped with high positioning accuracy.

As described above, in the optical carriage, by means of a drive assisting means composed of a rail curved vertically upward and a roller rolling along the rail, when the roller rolls up the rail, a part or the whole of the optical carriage is moved. The optical carriage rises as the rollers rise, and the optical carriage is braked by the increase in potential energy as it rises. Also, when the rollers roll down the rail, part or all of the optical carriage descends as the rollers descend, causing the optical carriage to move downward. The associated reduction in potential energy assists the drive of the optical carriage.

According to this embodiment, it is possible to reduce the burden on the drive motor 4 as a drive device, and to obtain an optical carriage that is reliably stationary at the home position. Furthermore, a drive assisting means with a simple configuration can be provided without providing a new drive source.

Example 2 (see FIGS. 4 to 8) This example is based on claim 3.
, corresponds to claim 4. The overall configuration of the drive system of the optical carriage is similar to that shown in FIG. The first optical carriage, rolling means, contact member, etc. according to this example will be explained with reference to FIG. 4.

The structure shown in FIG. 4 is functionally the same as the fluorescent lamp 5, reflector 6, mirror 8, etc. already explained in FIG. 2, and therefore is given the same reference numeral. A rolling element is provided below the first optical carriage and supported by support means. The support means comprises a shaft 1 integral with the first optical carriage.
1, and a bracket 12 that fits on this shaft 11 and can freely move forward and backward.
A roller 14 serving as a rolling element is pivotally supported at the lower end of the bracket 12.

The braking means is composed of a brake shoe 13 provided on the bracket 12 and constantly in contact with the roller 14 to apply a braking force to the rotation of the roller 14. An extensible spring 15 as a biasing means is installed inside the cylinder of the bracket 12 in which the shaft 11 moves forward and backward, and due to the action of this spring,
The bracket 12 is normally in a protruding state, and is locked in this state by a stopper (not shown).

Here, the bracket 12 and the shaft 11 slide smoothly, and the rollers 14, brake shoes 13, and bracket 12 move forward and backward (up and down) integrally. Also, Koro 1
4 is limited by friction with the brake shoe 13, resulting in a braking effect of the optical carriage.

Furthermore, a notch 17 is formed on the side of the bracket 12.
is formed, and when the roller 14 receives an external force and the bracket 17 retreats in the direction of compression of the spring 15, the latch 18 engages with this notch 17 to hold the bracket 12 in that position. . The latch 18 is pivotally supported by the first optical carriage 1 as shown in FIG. The bracket is pressed against the side of the bracket.

As shown in FIG. 5, the latch 18 has a protrusion 1.
8A is formed, which constitutes a part of a release means for releasing the engagement of the latch 18 engaged with the notch 17.

Next, an inclined rail-shaped contact member 16 is provided near the home position and on the passage path of the roller 14. The contact member 16 has the function of contacting the roller 14 over a range near the home position and keeping the roller in a rotating state at least when the optical carriage moves back toward the home position. Therefore, the contact member 16 is inclined so that its height increases as it approaches the home position.

Next, with reference to FIG. 6, the state of braking will be explained step by step. Here, the first optical carriage 1
In the figure, the robot sequentially moves backwards from left to right, and finally comes to rest securely at the home position. FIG. 6(a) shows the state before the start of braking. In this state, the rollers 14 are not in contact with any external member, so the first optical carriage does not exhibit any braking function and its movement is not restricted.

Here, a contact member 16 is provided near the home position at a position facing the roller 14. The movement of the first optical carriage progresses, and eventually the rollers 14 come into contact with the contact member 16, as shown in FIG. 6(b). At this time, since the bracket 14 is pushed downward by the spring 15, the roller 14 continues to be in contact with the contact member 16.

By setting the friction coefficient of the rollers 14 to be larger on the contact member than on the brake shoe 12 and appropriately determining the compression force of the spring 15, the rollers 14 and the contact member 16 While the first optical carriage 1 is in contact and moving, it continues to rotate. As mentioned above,
Rotation of the roller 14 is restricted by the brake shoe 13. As a result, the kinetic energy of the first optical carriage 1 can be consumed by the friction between the rollers 14 and the brake shoes 13, and the optical carriage is decelerated. In this way, the first optical carriage 1 that has been sufficiently decelerated comes to rest reliably as the rollers 14 abut against the ends of the contact members 16, as shown in FIG. 6(c).

Next, consider the case where the first optical carriage 1 moves forward in the opposite direction (scanning direction) to the backward movement direction. in this case,
It is undesirable for the movement of the optical carriage to be hindered due to the braking function being exerted. Therefore, the contact member 16 is supported so that the home position (FIG. 6(c)) is higher than the braking start position (FIG. 6(b)). Coupled with the fact that the contact member 16 is downwardly oriented to the right, the roller 14 is held at the height at the home position during forward movement (scanning), so that the roller 14 is moved downward to the contact member 16. It is possible to obtain a state in which the movement of the optical carriage is not braked by not making contact with the optical carriage.

The notch 17 and latch 18 are provided to achieve this condition. In other words, when the bracket 12 is pushed up in response to the backward movement of the first optical carriage 1 and the contact member 16 is inclined, and the notch 17 rises to the position of the latch 12, the latch engages with the notch. This will prevent the bracket from descending. During forward movement, this vertical position is maintained, so roller 1
4 and the contact member 16 are not in contact with each other, and no braking force is applied to the first optical carriage 1. FIG. 7(b) shows an unlatched state, and FIG. 7(a) shows a latched state.

Before the first optical carriage 1 starts to move backward again, the rollers 14 must return to a state where they can be braked (FIGS. 6(a) and 7(b)). Therefore, the release lever 20 is positioned at a spatial position in the forward movement direction relative to the leftmost part of the contact member 16, and at a position where the projection 18A passes.
Set it up.

As a result, the latched state (FIG. 8(
a)) Below the first optical carriage 1 as shown in FIG.
begins to move forward and when the roller 14 comes to the left side of the contact member 16, the protrusion 18A integrally formed with the latch 18 collides with the release lever 20 (Fig. 8(b)), and as it moves further, the latch 18 is released. It comes off (Figure 8(c)) and the bracket 12 falls (
8(c) and (d)), and the roller 14 returns to the position shown in FIG. 6(a).

[0038] According to this example, an optical carriage is provided which has a simple structure, safely and accurately stands still at the home position without placing any burden on the drive device, and has a braking function that is effective only during return movement. be able to.

[0039]

According to the present invention, it is possible to provide a simple means for reducing the burden on the drive device and safely and reliably stopping the optical carriage at the home position.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 2 is an explanatory diagram of a light source section of an optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 3 is a moving speed diagram of an optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 4 is a partial sectional view of an optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 5 is a perspective view of a latch of an optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 6 is a diagram illustrating step-by-step changes during the backward movement of the optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 7 is a diagram illustrating step-by-step changes in the forward movement of the optical carriage corresponding to claims 1 and 2 of the present invention.

FIG. 8 is a diagram illustrating step-by-step how the latch is released when the optical carriage moves forward, corresponding to claims 1 and 2 of the present invention.

FIG. 9 is a perspective view illustrating an optical carriage and its drive system as an embodiment of the present invention.

[Explanation of symbols]

1 First optical carriage 9 Rail 10 (as a guide) Roller 11 Shaft 12 (of the optical carriage) Bracket 14 Roller 16 (as rolling means) Contact member

Claims (4)

[Claims] Claims: 1. An optical carriage used in a document reading section of an image forming apparatus, which is guided along a guide and reciprocates from a home position when scanning a document, wherein the guide is located near the home position. The optical carriage is characterized in that the guide path changes so that the height of the optical carriage in the vertical direction tends to increase as the optical carriage approaches the home position during backward movement. 2. The optical carriage according to claim 1, wherein the guide is a rail curved near the home position, and rollers provided on the optical carriage roll on this rail. 3. An optical carriage used in a document reading section of an image forming apparatus and reciprocating while being guided along a guide when scanning a document; and a contact member extending over a range near the home position and capable of contacting the rolling element and placing the rolling element in a rotating state at least when the optical carriage moves back toward the home position. optical carriage. 4. The contact member according to claim 3, wherein the contact member is inclined so as to gradually push the bracket as the optical carriage approaches a home position during backward movement,
The rolling means is provided on the bracket so as to be movable forward and backward by engaging with the shaft of the optical carriage, and urging means for urging the rolling means in a direction to press the contact member against the contact member;
a locking means for locking the bracket at a position in the forward and backward movement direction of the bracket at the home position when the optical carriage reaches the home position, and releasing the lock during the forward movement process of the optical carriage. An optical carriage characterized in that it has a release means.