JPS6349106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reciprocating drive mechanism for an apparatus, such as a copying machine, having a moving body that moves forward and backward.

For example, in an electrophotographic copying machine, an original is fixed and a moving optical system is moved back and forth to perform optical scanning and project an image of the original onto a photoreceptor. In addition, there is also a method in which a document is placed on a movable table, the movable table is moved back and forth, and optical scanning is performed using a fixed optical system. In this case, in order to perform normal copying, the optical scanning speed of the moving optical system, moving table, etc. must be strictly constant.

Furthermore, in order to perform repeated copying, it is necessary to return the movable optical system, movable table, etc. to their original positions after optical scanning of the original is completed. At this time, in order to improve copying efficiency, the return time that is not used for copying operations must be minimized, that is, the return speed must be made as fast as possible compared to the optical scanning speed.

Furthermore, since moving optical systems and the like require precision and are generally not made with much strength, they must not be subject to large impact forces when the direction of movement is reversed. Furthermore, even in the case of a movable table, it is still undesirable to apply an impact force to the movable table, as this may cause the document placed on the table to move.

The reciprocating method for a moving body that requires the above performance is as follows: (1) From a drive source that moves in a fixed direction, use gears, etc. to generate both forward and reverse motion, and select a clutch, etc. to generate motion in both directions. Those that drive a moving object (2) Those that drive reciprocatingly using a forward/reverse motor, etc. (3) Those that only forward motion are controlled by a clutch, and the backward motion is driven by a dedicated motor, etc. (4) Those that drive only forward motion using a clutch The backward movement is driven by the elasticity of a spring or the like that is charged during the forward movement.

Among these, those that use a clutch reach a predetermined speed as soon as the clutch is engaged, so there is no loss time during startup and reversal, and efficiency is good, but a large impact force is applied. Particularly when the clutch is used for forward and reverse reversals as in (1), the difference in speed is large, so the impact force becomes enormous. Furthermore, the higher the copying speed, the greater the impact force, so when high-speed copying is performed, countermeasures against impact become a problem.

For those that use a special motor, etc., the motor starts slowly and does not generate the impact force that occurs with a clutch, but on the other hand, there is a large loss of time during start-up and reversal, making for efficient copying. is difficult to realize. In particular, when using a forward-reverse motor as in (2), the rotational speed of the motor is determined by the number of poles in the case of commonly used AC motors, and at most the backward movement is two times the forward movement. I can only do it twice as fast. It also has the disadvantage of being expensive.

Furthermore, for those that use a spring for return,
Since it is inexpensive and simple, and starts slowly, no impact force is generated during startup. but,
Due to the elasticity of the spring, the movable body continues to accelerate until it reaches the stop position, and the impact force at the stop position becomes large, and a complicated and expensive shock absorber must be provided to alleviate the impact. In addition, since the loss time during the start-up is large, the improvement in the average speed of the backward movement is not so large, as a result of the problem of shock absorption at the stop position.

In contrast to the conventional reciprocating drive method, which has various problems as described above, a method has been proposed in which reciprocating motion is extracted using a cam and a cam follower that rotate in a fixed direction. With this method, the shape of the cam can be made arbitrary, so the moving object can be controlled under ideal acceleration and deceleration conditions, so starting and decelerating without impact can be achieved.
Inversion can be performed. Further, the speed ratio of the reciprocating motion can be set arbitrarily, and copying can be carried out most rationally at high speed and with high efficiency. However, in the case of this method, unlike the conventional method, the speed of the moving object is created not by the rotation of a motor etc., but by the cam shape.
In order to create a strictly constant speed as in the case of optical scanning mentioned above, the cam shape must be carefully selected.
It must be precisely designed and processed with ultra-precision.

Therefore, a high level of machining technology is required, and the price is also very high.

Therefore, the present invention eliminates the drawbacks of the conventional methods, realizes smooth start and reversal without impact, strictly constant speed in forward movement, and high speed in backward movement, and achieves high-speed and highly efficient reciprocating of moving objects. It is an object of the present invention to provide a simple and inexpensive reciprocating drive device that can realize motion.

In the present invention, a reciprocating motion is obtained from a drive source of fixed direction motion using a quick return mechanism, and the obtained reciprocating motion is transmitted to an output means. On the other hand, the gist is to obtain a constant speed by regulating the forward movement speed of the output means so that it does not exceed a predetermined speed.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

The quick return mechanism of this embodiment is composed of a crank 1 and a swing lever 2. Crank 1 is shaft 3
The chain 4 and the sprocket 5, which are attached to a
(CCW) direction. On the other hand, the lever 2 is swingably supported by a shaft 6, and a roller ₇ at the tip of the crank 1 fits into a groove 21 provided in the longitudinal direction of the lever. As a result, crank 1
During one rotation in the CCW direction, the lever 2 makes one reciprocating swing. At this time, the swing time in the CCW direction is much longer than the swing time in the clockwise (hereinafter referred to as CW) direction.

A half-moon gear 8 is provided at the other end of the lever 2, meshing with a gear 10 on a shaft 9, and transmitting the swinging motion of the lever 2 at increased speed. The gear 10 is connected to the shaft 9,
It is attached via a coil spring 11. The details are shown in Figure 2.

The gear 10 is rotatably supported on the shaft 9, and a bent portion 11 ₂ of one end of the coil spring 11 is inserted into the hole 10 ₁ . The bent portion 11 ₂ at the other end of the coil spring 11 is connected to the shaft 9 facing the gear 10.
It is inserted into the hole 12 ₁ of the sleeve 12 provided above. Further, the pin 10 ₂ on the gear 10 is fitted into the long groove 12 ₂ of the sleeve 12, and the gear 10 and the sleeve 12 can rotate relative to each other within the range of the long groove 12 ₂ . The pin 10 ₂ is inserted into the long groove 1 with the coil spring 11 wound tightly to some extent.
2 will be inserted into ₂ . Therefore, in this state, pin 1
0 ₂ is located at the illustrated position within the long groove 12 ₂ . The sleeve 12 is fixed to the shaft 9 with a set screw 13.

Returning to FIG. 1 again, a wire drum 14 is attached to one end of the shaft 9, and a wire 15 wound around the wire drum 14 is connected to a moving body (not shown).

Further, a sprocket 16 with a chain 4 is provided on the shaft 9. Sprocket 16
An overrunning clutch 17 is disposed between the sprocket 16 and the sprocket 9, so that when the shaft 9 attempts to rotate in the CW direction at a faster speed than the sprocket 16, the two are coupled together. Also, lever 2
A spring 18 is applied to apply force in the CW direction.

Next, the operation of this mechanism will be explained.

When the crank 1 rotates in the CCW direction from the illustrated position, the lever 2 begins to swing in the CCW direction, and its speed increases. This movement is accelerated and transmitted to the gear 10, and then to the shaft 9 via the coil spring 11. When the swing speed of the lever 2 in the CCW direction increases, the rotation speed of the gear 10 in the CCW direction exceeds the rotation speed of the sprocket 16 in the CW direction. Then, overrunning clutch 17
sprocket 1, and the rotational speed of shaft 9 is
6, and it is impossible to increase the rotation speed any further. When the rotational speed of the gear 10 further increases, the gear 10 overcomes the tightening force of the coil spring 11 and is relatively rotationally displaced in the CW direction on the shaft 9. Furthermore, as the crank 1 continues to rotate, the rotation speed of the lever 2 in the CCW direction begins to decrease, but the shaft 9 continues to rotate at the same speed as the sprocket 16 while the rotational displacement of the coil spring 11 remains. continue. When the crank 1 continues to rotate and the lever 2 reaches the end of its swing range and changes to the CW direction, the gear 10 changes to the CCW direction and the pin 10 ₂ moves into the long groove 12 ₂ of the sleeve 12. Press the end of the shaft to rotate the shaft 9 in the CCW direction. At this time, the overrunning clutch 17 is disengaged.

The relationship between the rotation angle θ ₁ of the crank 1 and the rotation angle θ ₂ of the shaft 9 and gear 10 in this mechanism is shown in FIG. First, the shaft 9 gradually accelerates together with the gear 10 until the speed of the gear 10 reaches the speed of the sprocket 16 (run-up region), and when the gear 10 becomes faster than the sprocket 16, the shaft 9 rotates at a constant speed (synchronization region). Gear 10 gradually shifts. And when gear 10 reverses,
The shaft 9 catches up with the gear 10, and then the gear 10
At the same time, it rapidly rotates backwards to complete one cycle.

Next, the shape of the lever 2, which determines the movement of the shaft 9 such as rising and reversal, that is, the movement of the gear 10, will be explained.

FIG. 4 shows a general crank lever mechanism that is not used in the present invention. The number of each part is
Add 100 to the number in Figure 1. The extension of the groove 102 ₁ of the lever 102 passes through the shaft 106 .
The rotation radius of the crank 101 is R, the shaft 103 and the shaft 1
Let L be the distance from 06, and let L=nR. The crank 101 rotates counterclockwise in the drawing, and the rotation angle α of the crank 101 is a value measured from a line connecting the shafts 103 and 106 in the direction of rotation of the crank. Furthermore, the rotation angle β of the lever is a value measured counterclockwise from the same line.

FIG. 5 shows the relationship between angles α and β in this mechanism, using the value of n as a parameter.
The smaller the value of n, that is, the axis 103 and axis 106
The closer the distance, the faster the lever 102 swings counterclockwise, and the more rapidly the lever 102 is decelerated and accelerated during reversal. Considering this from the above-mentioned purpose, the smaller n is, the faster the return motion is, and the less loss occurs during reversal and rise. However, if n is made too small, the swing width of the lever 102 increases, making it mechanically unreasonable. FIG. 6 is the same relational diagram as FIG. 3 when the mechanism of FIG. 4 is incorporated into FIG. 1. This is n=
This is the case for 1.5. For efficiency, it is better to have as few run-up areas as possible. Furthermore, it is advantageous in terms of efficiency that the ratio of the time required for the forward movement to the time required for the backward movement is as large as possible, since the return speed will be relatively high. The engagement speed (synchronous speed) of the overrunning clutch 17 is determined based on these considerations. However, in the case of FIG. 6, the start of the forward movement is rather slow and there is no problem, but when the movement is reversed to the backward movement, the movement is discontinuous. In this way, discontinuous movements are always accompanied by shocks. In order to speed up the start-up, reduce the run-up area, and eliminate the impact when reversing, the movement of the gear 10 should be rapid at the start-up and gentle at the time of reversal. Part 2
The crank lever mechanism adopted in the present invention satisfies these two conditions.

This will be explained with reference to FIGS. 7 and 8.

In the crank lever mechanism shown in Figure 7, the numbers for each part are the numbers in Figure 1 plus 200. The rollers 207 of the crank 201 are connected to the shaft 203 and the shaft 206
When the groove 202 of the lever 202 is on the line connecting the
₁ is inclined by an angle γ with respect to a line connecting both axes. That is, unlike in the case of the general lever 101 of FIG. 4, the extension of the groove 202 ₁ does not pass through the shaft 206 . By setting the angle γ in this way, the relationship diagram (FIG. 5) between the rotation angle α of the crank 201 and the swing angle β of the lever becomes distorted.
This is shown in Figure 8. This is the case when n=1.5,
The cases where γ=0, 30°, and 45° are shown. As is clear from this, as the angle γ increases, the rise becomes more rapid, while the reversal becomes more gradual. Also, the backward movement speed becomes faster. Therefore, by appropriately selecting the angle γ, the above-mentioned conditions can be satisfied. FIG. 3 is a diagram of the relationship between the movements of the crank 1, shaft 9, and gear 10 when the lever with n=1.5 and γ=45° in this figure is used as the lever 2 in FIG. 1. According to this, since the start-up is quick, the run-up range is small, and since the reversal of the shaft 9 connects to the gear 10 which changes gradually, the impact is much less. Also, the return speed is fast,
Efficient reciprocating motion can be obtained.

Next, the action of the spring 18 will be explained. This mechanism obtains slow forward movement and rapid backward movement from a single drive source, and the driving force of crank 1 is able to handle load fluctuations such as being light during forward movement and heavy during backward movement. arise. Due to this load variation, the speed of the chain 4 etc. may change. In copying machines and the like, the image forming process is generally performed by the same driving source, and it is not desirable for the speed of this to change. The spring 18 is used to deal with this, and since the force applied to the lever 2 is in the CW direction, it acts as a load on the driving force during forward movement, and acts in a direction to assist the driving force during backward movement.
Therefore, the driving force can be an average load over one reciprocation of the lever 2, and no speed change occurs. Further, even if an overrunning clutch is used, what is coupled to the shaft 9 need not be the same driving source as the crank 1, but may be a separate member rotating at a constant speed.

Since the present invention has the above configuration, it has various effects.

First, since continuous deceleration and acceleration are performed during rising and reversing, smooth reciprocating motion can be obtained without impact.

Secondly, the speed of the backward movement can be much greater than that of the forward movement, so it is efficient.

Thirdly, since the forward motion starts quickly, there is no loss time and efficiency is high.

Fourthly, the constant forward movement speed is determined by the constant speed regulating means, so it is strictly constant speed regardless of the quick return mechanism. Conversely, a quick return mechanism does not require the same precision as when creating speed with a conventional cam.

Fifth, even if some vibration occurs due to poor machining accuracy of the quick return mechanism, it is absorbed by the elastic joint and is not transmitted to the output shaft, which rotates at a constant speed. Therefore, the processing accuracy of the quick return mechanism may be low, and the cost can be reduced. Furthermore, no problems occur in terms of durability.

Sixthly, the driving force required for reciprocating the driving source can be made almost uniform, and speed fluctuations of the driving source can be prevented.

Seventh, because it can be constructed from simple and inexpensive elements,
The entire device can be manufactured compactly and at low cost.

As described above, the present invention is very useful since it is possible to obtain a reciprocating drive device having various effects.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a perspective view showing an embodiment of the present invention;
The figure is a partially detailed perspective view of Figure 1, Figures 3 and 6 are diagrams showing the relationship between the rotation angle θ ₁ of the crank and the rotation angle θ ₂ of the shaft, and Figure 4 is an enlarged view of the crank lever mechanism. ,
5 and 8 are diagrams showing the relationship between rotation angles α and β in the flank lever mechanism, and FIG. 7 is an enlarged view of the crank lever mechanism of the present invention. 1 is the crank, 2 is the swing lever, 4 is the chain,
7 is roller, 8 is half-moon gear, 9 is shaft, 10 is gear,
11 is a coil spring, 12 is a sleeve, and 17 is an overrunning clutch.

Claims (1)

[Claims] 1. A drive source that rotates in one direction, a crank that is rotationally driven in one direction by the drive source, and a linear guide surface on which a crank pin of the crank is engaged and guided, A lever that makes a reciprocating movement about a shaft in which the time required for forward movement is longer than the time required for backward movement, the lever having the linear guide surface and the shaft separated by a predetermined distance; a rotating body that is caused to reciprocate by rotating; and a rotating body that is connected to the rotating body via an elastic member;
A movement having the following: an output shaft that outputs a driving force for reciprocating a moving body; a constant speed movement means for moving at a constant speed; and an overrunning clutch means interposed between the output shaft and the constant speed movement means. A reciprocating drive mechanism for bodies, etc.