JPH06159459A - Power transmission device - Google Patents

Abstract

PURPOSE:To smoothly feed an endless sheet with no oscillation even though an electronic blackboard, without being affected by variation in load, and to precisely read an image so as to carry out high quality printing. CONSTITUTION:In a power transmission device comprising a transmission member 10 for transmitting a power from a drive part to a driven part, guide members 1a, 1b made into slidable contact with the transmission member 10, and a resilient member 12 for always urging the guide members so as to make them into press-contact with the transmission member 10 in order to rotate the resilient member 12 so that degrees of push-in of the transmission member 10 by the guide members are different from each other, a regulating member 2 regulates the positions of the guide members.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device for conveying and driving a large-sized endless sheet used for a display portion of an electronic blackboard, and particularly transmitting torque from a driving portion to a driven portion by a transmission member. The present invention relates to improvement of a power transmission device.

[0002]

2. Description of the Related Art FIG. 4 is a diagram for explaining the structure and principle of an electronic blackboard to which a conventional power transmission device is applied, showing a power transmission device for transporting and driving a large endless sheet for an electronic blackboard. This power transmission device includes a drive roller 103 that rotates by receiving a drive force from a motor (not shown).
Driven rollers 104a to 104c arranged in a predetermined positional relationship with the driving roller 103, an endless sheet 105 stretched around these rollers 103, 104a to 104c, and an endless sheet. A light source 106 is disposed at a position where the driven roller 104a is folded back and illuminates the surface of the driven roller 104a, and a mirror 10 for receiving the reflected light (image information on the endless sheet 105).
7 and a lens 10 for collecting the reflected light from the mirror 107
8, a line sensor 109 for photoelectrically converting the image information on the endless sheet 105, and a printer 116 based on the image information as an electric signal from the line sensor 109.
Control unit 1 for outputting a control signal to the printer to print on paper
15 and. A motor pulley 111 fixed to the output shaft of a stepping motor (not shown) and the drive roller 10
A timing belt (transmission member) 110 is hung between the pulley 3 and a not-illustrated coaxial pulley, and the endless sheet 105 is conveyed by rotationally driving the driving roller 103 via the timing belt 110.

When the endless sheet 105 is conveyed in the above state, the following problems occur. That is,
FIG. 5 is a perspective view showing the structure of a large-sized endless sheet, and since the endless sheet 105 is formed by joining both ends of an endless sheet by heat welding,
The seams are usually harder and thicker than the rest. Therefore, the joint portion is driven roller 104a ~
At the time of approaching 104c and passing therethrough, the carrying load fluctuates greatly. In such a state, the timing belt (transmission member) 110 and the motor pulley 111
The tooth belt of the timing belt (transmission member) 110 is skipped at the meshing part with, and accurate reading and printing cannot be performed. In order to prevent this tooth jump, it is conceivable to set a large distance between the motor pulley 111 and the pulley of the drive roller 103 (not shown) so as to give a sufficient tension to the timing belt 110. Accurate reading and printing could not be performed due to motor out-of-step due to fluctuations. Further, when the motor is driven, a high torque is generated due to the characteristics of the motor, and the vibration is transmitted to the timing belt 110 via the motor pulley 111 due to the large torque at the start-up, and the timing belt 110 is further wound around the motor. The noise was transmitted from the pulley of the driving roller 103 to each part, and became a noise, giving an unpleasant feeling. Further, in order to prevent the tooth jumping, the motor step-out, and the noise as described above, the belt tension is adjusted in order to keep the axial distance between the pulley of the drive roller 103 and the motor pulley 111, which is not shown, constant. ,
Although the adjustment range is very narrow and the adjustment is time-consuming, the effect of preventing tooth jump etc. was low.

FIG. 6 is an explanatory view of the structure of a power transmission device already proposed by the present inventor, FIG. 7 is a front view of a main portion of the seat drive portion of FIG. 6, and FIG. 8 is a plan view showing an operating state of the seat drive portion. Figure 9
FIG. 10 is an explanatory diagram showing a relationship between reading and printing results of an electronic blackboard according to the conventional technique, and an improved power transmission device as shown in FIGS. 6 to 9 is also proposed in order to solve the above-mentioned problems of the power transmission device. However, it is not satisfactory as a power transmission device for an electronic blackboard that requires high accuracy. That is, in the power transmission device shown in FIG. 6, a roller (guide member) rotatably press-contacted to the outer surfaces of the first traveling surface 110a and the second traveling surface 110b of the timing belt (transmission member) 110 which face each other. ) 101a and 101b are
A bifurcated spring (elastic member) 112, which is an elastic member, is rotatably supported by two tip portions 102a. The spring (elastic member) 112 is a torsion spring in which a central fulcrum portion 112b is provided with a twisted portion, and each of the rollers (guide members) 101a, 1a is centered around the twisted fulcrum portion 112b.
01b is pressed in the direction of arrow A (inward direction). Figure 7
As shown in, the set screw 113 is inserted into the hollow inside of the fulcrum 112b at the center of the spring (elastic member) 112, and the set screw 113 is attached to the support plate 114. The spring (elastic member) 112 has a fulcrum 1
It can be rotated around 12b. Usually, when the power from a stepping motor (not shown) is not transmitted, or when the timing belt (transmission member) 110 is conveyed at a constant speed, the first traveling surfaces of the timing belt (transmission member) 110 facing each other. 110a and second running surface 110b
The roller (guide member) 101 is pressed toward the inside by a uniform pressure on the outside of the central portion of the above, which is a stable state.

As shown in FIG. 8, at the moment when the motor pulley 111 rotates in the forward direction, a timing belt (transmission member)
Of the two traveling surfaces facing each other of 110, the first traveling surface 110a on the upstream side is the tension side, and the second traveling surface 110b on the opposite side is the loosening side instantaneously. At that time, one roller (guide member) 101a is pressed in the direction of arrow B by the tension of the running surface 110a of the timing belt (transmission member) 110 on the tension side. The roller (guide member) 101a and the roller (guide member) 101b are caused by the contracting force of the spring (elastic member) 112 toward the inside to cause the timing belt (transmitting member) 11 to move.
Since 0 is pushed inward and the fulcrum portion 112b is rotated as a center, the other roller (guide member) 101b corrects the looseness of the second traveling surface 110b of the timing belt (transmission member) 110 [as shown in the figure. Then, the timing belt (transmission member) 110 on the second traveling surface 110b is bent to maintain the tension] while moving in the direction of arrow B. Then it stops in a stable position. When the motor pulley 111 rotates in the reverse direction, the reverse operation is performed.

By the way, when the drive roller 103 is rotating at a constant speed and a load caused by the seam of the endless sheet 105 (see FIG. 5) is instantaneously applied to the drive roller 103, the timing belt (transmission member) 110 6 is in contact with the roller (guide member) 101 in a bent state as shown in FIG. 6, the first traveling surface 110a of the timing belt (transmitting member) 110
Traveling surface 110b is in the direction of each arrow C (outside)
Try to spread to. However, each traveling surface 110a, traveling surface 1
Since the rollers 10b are pressed inward by the roller (guide member) 101 and the spring (elastic member) 112, the load is absorbed as tension. Therefore, no sudden load change is transmitted from the motor pulley 111 to the shaft of the stepping motor. Therefore, the stepping motor is not out of step.

Since the distance between the spring (elastic member) 112 and the roller (guide member) 101 is long and the fulcrum portion 112b is rotatable, the spring constant is made as small as possible so that a constant pressing force is always applied. In addition to being obtained, a constant pressing force is instantly applied regardless of whether it is rotated in the forward or reverse direction. The roller (guide member) 101 is rotatable and reduces the load at the time of contact with the timing belt (transmission member) 110.

The above-mentioned power transmission device surely transmits power to a large endless sheet wound around a plurality of rollers and running, regardless of load, and
It is an improved power transmission device that does not require adjustments for noise reduction. However, the seams (see FIG. 5) on the endless sheet 105 are the driven rollers 104a-104.
When the carrying load is instantly increased by approaching c, when the motor is instantly started up when the motor is started, the user who uses the electronic blackboard touches the endless sheet 105 with his / her hand or writing instrument to temporarily increase the load. When it becomes,
The spring (elastic member) 112 is momentarily moved to the side to which the load is applied, and when the next moment the load is reduced, the spring 112 swings in the opposite direction, and is left and right for a certain period of time without being applied with the roller (guide member) 101. Rock. As a result, when an oblique straight line is written and read on the endless sheet 105 and printed by the printer 116, a partially distorted straight line appears on the paper 117 (see FIG. 9). Endless seat 105
In the state of conveyance, since the sheet is conveyed while swinging in the conveying direction, the appearance is not good.

[0009]

In the above-described power transmission device, when the load temporarily increases, the elastic member momentarily moves to the side to which the load is applied, and the next instantaneous load decreases. Although it swings in the opposite direction and no load is applied,
It sometimes rocked to the left and right along with the guide member for a certain period of time. When this power transmission device is applied to a power transmission device for conveying and driving a large endless sheet on an electronic blackboard, an oblique straight line is written on the endless sheet and read, and when printed by a printer, some distortion on the paper occurs. A straight line appears, and the endless sheet is conveyed while swinging in the conveying direction, and therefore the appearance is not good.

[0010]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve such a problem. That is, even if applied to an electronic blackboard, the endless sheet is smoothly conveyed without being shaken even if it is applied to an electronic blackboard without being affected by load fluctuations, images are read with high accuracy, and high-quality printing is performed. An object is to provide a transmission device.

[0011]

To achieve the above object, the present invention provides a transmission member for transmitting power from a drive unit to a driven unit, and a guide member slidably contacting the transmission member.
The position of the guide member is restricted in an elastic member that constantly presses the guide member against the transmission member and in a power transmission device that rotates the elastic member so that the pushing amount of the transmission member by the guide member is different. The most main feature is that it is a power transmission device provided with a regulating member for controlling.
The main feature is that the restricting member has an elastic portion.

[0012]

According to the power transmission device configured as described above, the regulation member regulates the lateral swinging of the elastic member for a certain period of time without any load being applied to the elastic member, thereby preventing a large load fluctuation together with the guide member. Provided is a power transmission device that is not affected by this, and even when applied to an electronic blackboard, the endless sheet is conveyed smoothly without rocking, images are read with high accuracy, and high quality printing is performed. can do.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. Note that FIG. 7 is also referred to. FIG. 1 is a plan view of a main part of a power transmission device according to an embodiment of the present invention,
In FIG. 1, rollers (guide members) 1a rotatably pressed against outer surfaces of a first traveling surface 10a and a second traveling surface 10b of a timing belt (transmission member) 10 facing each other.
b is 2 of a bifurcated spring (elastic member) 12 which is an elastic member.
It is rotatably supported by two tip portions 12a.
The spring (elastic member) 12 is a torsion spring in which a central fulcrum portion 12b is provided with a twisted portion, and the rollers (guide members) 1a and 1b are moved around the torsional fulcrum portion 12b in the arrow A direction (inward direction). ). Similarly to the conventional example shown in FIG. 7, a set screw 13 is inserted into the hollow inside of the central fulcrum 12b of the spring (elastic member) 12, and the set screw 13 is attached to the support plate 114. . The spring (elastic member) 12 can rotate about its fulcrum 12b. Normally, when power from a stepping motor (not shown) is not transmitted, or when the timing belt (transmission member) 10 is conveyed at a constant speed,
The roller (guide member) 1 is pressed inward by a uniform pressure on the outer sides of the central portions of the first traveling surface 10a and the second traveling surface 10b of the timing belt (transmission member) 10 facing each other. And this is a stable state.

In this embodiment, the regulating members 2 made of elastic members such as springs are arranged on the outer sides of the traveling surfaces 10a and 10b facing each other of the transmission member 10 made of a timing belt and the like. The structure in which the arms 12c are biased inwardly is different from the conventional example. One end of each of the regulation members 2 is supported and positioned by the support portion 18 of a fixed member such as a support plate, and the other end is supported and positioned by the arm 12c of the elastic member 12. Upstream side regulating member 2a of the regulating member 2
And the downstream regulating member 2b have the same elastic force. When the apparatus is stopped, it is in the state shown in the figure and is in a stable state in the neutral position.

FIG. 2 is a diagram for explaining the operation of the apparatus shown in FIG. 1, and at the moment when the stepping motor (not shown) is driven and the motor pulley 11 starts to rotate in the forward direction, the traveling surfaces 10a and 10a of the transmission member 10 which face each other. The upstream running surface 10a of 10b is the tension side, and the opposite downstream running surface 1
0b is instantly on the loose side. At that time, one guide member 1a is pressed in the direction of arrow B by the tension of the running surface 10a on the tension side. Since the guide members 1a and 1b press the transmission member 10 inward by the contracting force of the elastic member 12 toward the inside, and rotate about the fulcrum portion 12b, the other upstream guide member 1b. Moves in the direction indicated by arrow B while correcting the looseness of the downstream traveling surface 10b of the transmission member 10 (bending the downstream traveling surface 10b of the transmission member 10 in the B direction to maintain the tension as shown). .
At this time, since the upstream guide member 1a is pressed inward by the upstream regulating member 2a, which is an elastic portion such as a spring, in the direction opposite to the arrow B direction, the arrow B of the upstream guide member 1a.
While the movement in the direction is performed gently, the guide member 1
The movement of b in the direction of arrow B is instantaneously performed. In this way, the next instantaneous load when the elastic member 12 rotates in the B direction becomes smaller, the upstream traveling surface 10a of the transmission member 10 becomes a slack side, and the elastic member 12 as a whole is in the opposite direction (in the B direction). I try to return to the opposite direction instantly. However, on the other hand, since the elastic member 12 is pressed in the arrow B direction by the downstream side regulating member 2b, the elastic member 12 cannot instantaneously return in the direction opposite to the B direction, and as a result, the elastic member 12 and the guide member 1 are elastic. The member 12 swings only a small number of times, and the displacement amount is small and stops. When the motor pulley 11 rotates in the reverse direction, the reverse operation is performed.

When the drive roller 3 is rotating at a constant speed and a load caused by the seam of the endless sheet 5 (see FIG. 5) is instantaneously applied to the drive roller 3, the guide roller 1 bends. Since they are in contact with each other in a state, the upstream traveling surface 10a and the downstream traveling surface 10b of the transmission member 10 try to swing in the respective stretched directions (outward) in the arrow C direction according to the load fluctuation, but the regulating member 2 By elastic member 12
Is pressed inwardly in the direction opposite to the direction of arrow C, the elastic member 12 is brought into a stable state with the guide member 1 such that the displacement amount decreases with a small number of swings.

Therefore, when the endless sheet 5 of the electronic blackboard is conveyed by the power transmission device, when the stepping motor rises and falls and the load changes due to the seam of the endless sheet 5 and the like, the endless sheet 5 is conveyed with respect to the conveying direction. Since the sheet is not shaken and is not conveyed and is smoothly conveyed, even if a diagonal line is written on the endless sheet 5 and read, printing with high print quality can be obtained as shown in FIG. As the restriction member 2, a liquid damper may be used instead of an elastic member such as a spring. Since the description of the other configurations other than the above-described configuration is the same as the description of the conventional example shown in FIGS. 4 to 9, duplicated description will be omitted.

[0018]

Since the present invention is constructed as described above, the regulating member regulates the lateral swinging for a certain period of time even when no load is applied to the elastic member. It is not affected by a large load fluctuation together with the guide member, and even when applied to an electronic blackboard, the endless sheet is conveyed smoothly without rocking, images are read with high accuracy, and high quality printing is performed. The power transmission device can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a power transmission device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an operating state of a main part of the power transmission device according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of reading and printing results of the electronic blackboard according to the embodiment of the present invention.

FIG. 4 is a plan view showing the configuration and principle of an electronic blackboard to which a power transmission device of a conventional technique is applied.

FIG. 5 is a perspective view of a large-sized endless sheet showing a state of a joint of the electronic blackboard.

FIG. 6 is a plan view showing a configuration of a seat driving unit of an electronic blackboard to which a power transmission device of a conventional technique is applied.

FIG. 7 is a front view of a main part of the seat drive unit in FIG.

FIG. 8 is a plan view showing an operating state of the seat driving section of FIG.

FIG. 9 is an explanatory diagram of reading and printing results of an electronic blackboard according to a conventional technique.

[Explanation of symbols]

1 ... Guide member, 1a ... Upstream guide member, 1b.
..Downstream side guide member, 2 ... Regulating member, 2a ... Upstream side regulating member, 2b ... Downstream side regulating member, 3 ... Drive roller, 3a ... Pulley, 4a-4c ...・ Following roller, 5 ・ ・ ・ Endless sheet, 6 ・ ・ ・ Light source, 7 ・
..Mirrors, 8 ... Lenses, 9 ... Line sensors,
10 ... Transmission member, 10a ... Upstream running surface, 10
b ... Downstream running surface, 11 ... Motor pulley, 12
... Elastic member, 12a ... Tip part, 12b ... Support point part, 13 ... Set screw, 14 ... Support plate, 15 ...
・ Control unit, 16 ... Printer, 17 ... Paper, 18
... Supporting part, 101 ... Roller (guide member), 101
a ... upstream roller (upstream guide member), 101b ...
・ Downstream roller (downstream guide member), 103 ... drive roller, 103a ... pulley, 104a to 104c ...
-Following roller, 105 ... Endless sheet, 106
... Light source, 107 ... Mirror, 108 ... Lens, 109 ... Line sensor, 110 ... Timing belt (transmission member), 110a ... Upstream running surface,
110b ... Downstream running surface, 111 ... Motor pulley, 112 ... Spring (elastic member), 112a ... Tip, 112b ... Support point, 113 ... Set screw, 1
14 ... Support plate, 115 ... Control part, 116 ...
Printer, 117 ... Paper.

Claims (2)

[Claims] 1. A transmission member for transmitting power from a drive unit to a driven unit, a guide member slidably contacting the transmission member, an elastic member for constantly pressing the guide member to the transmission member, and the guide member. A power transmission device configured to rotate the elastic member such that the pushing amount of the transmission member is different,
A power transmission device characterized in that a restriction member for restricting the position of the guide member is engaged with the elastic member. 2. The power transmission device according to claim 1, wherein the restriction member has an elastic portion.