JP2566319B2 - Timing belt drive mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a timing belt drive mechanism, and more specifically, a timing belt driving mechanism that is driven by rotation of a drive pulley that meshes with the timing belt to drive a timing belt. The present invention relates to a timing belt drive mechanism that moves a body.

[Prior Art] This type of timing belt drive mechanism is widely adopted as a carriage drive mechanism for moving a recording head of a serial type recording apparatus (printer), for example. In a recording apparatus having such a carriage drive mechanism, a configuration in which a motor as a drive source of the carriage drive mechanism is commonly used as a drive source of a paper feeding mechanism that feeds recording paper is often used. Further, in order to continuously feed the paper while the carriage is stopped in such a configuration, the timing belt is provided with a toothless portion over a predetermined length, and the drive pulley of the timing belt has a timing portion at the toothless portion. A structure is adopted that allows the belt to idle.

FIGS. 12 (A) and 12 (B) explain the structure and operation of the timing belt of the carriage driving mechanism of such a conventional recording apparatus.

In both figures, reference numeral 106 is a timing belt for transmitting the driving force to the carriage of the recording head (not shown). The timing belt 106 includes a belt drive pulley (hereinafter abbreviated as drive pulley) 125 rotatably provided on the chassis 102 of the apparatus and three idler pulleys (driven pulleys) 128.
It touches each of A to 128C and is stretched by meshing with them.

Teeth are formed at a predetermined pitch on the inner surface of the timing belt 106, and the cross-sectional shape of these teeth along the belt length direction corresponds to the teeth of each pulley 125, 128A to 128C, and is formed in a substantially trapezoidal shape close to a rectangle. ing. Since the timing belt 106 is formed of an elastic material, it is generally formed with such a tooth cross-sectional shape so as to reliably transmit the driving force. Further, on the inner side surface of the timing belt 106, the above-described toothless portion is provided over a predetermined length as indicated by reference numeral 106a. Further, a convex portion 106b is provided at a predetermined position on the outer side surface of the timing belt 106, and a carriage of a recording head (not shown) is positioned and coupled to the convex portion 106b.

With such a structure, at the time of recording, the drive pulley 125 is rotated in the direction of arrow A in FIG. 12A by driving a motor (not shown). Along with this, the timing belt 106 travels clockwise in the figure, the carriage is moved in the C direction, the recording head is driven, and recording is performed. In this case, the rotational driving force of the motor (not shown) in the A direction is not transmitted to the paper feeding mechanism (not shown).

When the carriage returns, the drive pulley 125 is rotationally driven in the B direction, the timing belt 106 runs counterclockwise, and the carriage is moved in the arrow D direction. In this case, the rotational driving force in the B direction is transmitted to the paper feeding mechanism,
A predetermined amount of paper is fed corresponding to the interval between recording lines.
By repeating this, a plurality of lines are recorded.

On the other hand, during continuous paper feeding before or after the start of recording, as shown in FIG. 12B, the drive pulley 125 moves to the position where the timing belt 106 runs to the position where the toothless portion 106a contacts the drive pulley 125. Driven to rotate. In this case, the carriage (not shown) comes into contact with the wall on the right side of the figure (not shown) of the device and is forcibly stopped,
When the timing belt 106 is stopped, the drive pulley 125 idles with respect to the timing belt 106. That is, when the carriage is stopped, B of the motor of the drive source (not shown)
The rotational driving force in the direction is transmitted to the paper feeding mechanism to continuously feed the recording paper.

When recording is to be carried out again after the continuous paper feed is completed, the timing belt 106 runs slightly clockwise by the frictional force acting between the pulley 125 and the belt 106 by rotating the drive pulley 125 in the A direction. To do. The tooth 106c at the end of the toothed portion facing the left end of the toothless portion 6a of the timing belt 106 in FIG. 12B is the drive pulley 12.
5, the driving force is transmitted by meshing, and the carriage can be moved in the C direction.

[Problems to be Solved by the Invention] However, in the above configuration, the driving pulley 125 is rotationally driven in the direction A from the state shown in FIG. 12 (B), and the timing belt 106 is moved slightly clockwise by the frictional force to perform the timing. When the drive pulley 125 is meshed with the toothed portion of the belt 106, the position of the tooth 106c at the end of the toothed portion of the timing belt 106 and the position of the tooth of the drive pulley 125 do not always match. As shown in FIGS. 13A to 13B, the teeth 125a of the drive pulley 125 may ride on the teeth 106c of the timing belt 106. In this case, when the drive pulley 125 further continues to rotate in the A direction, the timing belt 106 moves with the teeth 125a of the drive pulley 125 successively riding on the teeth subsequent to the teeth 106c of the timing belt 106.

Figure 14 shows the results of an experimental examination of the occurrence rate of such tooth run-up.
The relationship between the feed amount of the drive pulley 125 from the start point of meshing with and the ride-on occurrence rate is shown. As the conditions for this experiment, the tension of the timing belt was 150 gf and the drive pulley 125
Has a rotation speed of 300 RPM and the pulley feed rate is 130 mm / sec.
And As shown in FIG. 14, the occurrence rate is as high as 80% when the feed amount of the pulley is about 1 mm from the meshing start point, and thereafter, the occurrence rate decreases as the feed amount increases.

In such a state where the riding of the timing belt 106 occurs, the teeth of the drive pulley 125 riding on the teeth of the timing belt 106 slip off and suddenly return to the normal meshing state, and the running of the timing belt 106 becomes unstable. Such an unstable riding state may continue until the recording head is transferred to the recording area. In that case, the carriage movement becomes unstable due to unstable timing belt running, and as a result, recording quality is degraded. May be defective.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is not limited to the carriage driving mechanism of the recording apparatus described above, and is to prevent the occurrence of the above-described teeth of the driving pulley on the timing belt teeth in the same timing belt driving mechanism.

[Means for Solving the Problem] In the present invention, in order to solve the above-mentioned problem, a timing belt in which teeth of a predetermined shape are formed at a predetermined pitch is caused to travel by rotational driving of a drive pulley that meshes with the belt. In a timing belt drive mechanism for moving a driven body coupled to the belt, the timing belt is provided with a toothless portion for idling the drive pulley with respect to the belt, and the toothed portion of the belt is provided with the toothless portion. At least one shape of the teeth facing both ends of the toothless portion is different from the shape of the other teeth of the belt, and has a structure in which the teeth of the drive pulley are hard to ride on.

[Operation] According to this structure, the timing belt is driven by the rotational drive of the drive pulley from the state where the toothless portion of the timing belt is in contact with the drive pulley, and the toothed portion of the belt is meshed with the drive pulley. In this case, due to the shape of the teeth located at both ends of the toothless portion of the toothed portion of the timing belt, it is difficult for the teeth of the drive pulley to ride on the teeth,
The occurrence of riding can be prevented.

[Examples] Hereinafter, details of examples of the present invention will be described with reference to the drawings.

1 to 11 illustrate the structure of a recording apparatus (printer) according to an embodiment of the present invention, which is related to the present invention. In this recording apparatus, the structure related to the present invention is adopted for the carriage drive mechanism for moving the recording head.
The carriage drive mechanism of the recording apparatus and the paper feed mechanism for recording paper that shares a drive source with the mechanism will be described below.

First, an outline of the configurations of the carriage driving mechanism and the paper feeding mechanism of the recording apparatus of this embodiment will be described with reference to FIGS. 5 and 6. Both figures show the main part of the recording apparatus main body.

In FIGS. 5 and 6, reference numeral 5 is a carriage on which a recording head (for example, an inkjet head) 8 is mounted and which is moved. The carriage 5 is slidably provided on a guide shaft 4 installed in the frame 1 of the recording apparatus and a guide rail portion 1c formed in the frame 1, and is mounted on the recording table fixed to the upper portion of the frame 1. Platen 12
It is provided so as to be slidable in the directions of arrows C and D in parallel with. A timing belt 6 is connected to the carriage 5,
As will be described later, the driving force is transmitted to the carriage 5 via the belt 6, and the carriage 5 runs in the C and D directions.

The carriage 5 is the wall 1b on the right side of the frame 1 in FIG.
The position where the carriage 5 abuts is the home position of the carriage 5. Whether or not the carriage 5 is located at the home position is detected by a home position sensor 14 provided on the frame 1. A flexible cable 13 is connected to the carriage 5 for applying a drive signal according to print data to the print head 8 from a control unit (not shown) of the printing apparatus.

On the other hand, in FIG. 6, reference numeral 9 is a paper feed roller for feeding the recording paper 11. The paper feed roller 9 is provided near the lower part of the platen 12, and is fixed to and rotatably supported by a shaft 21 rotatably supported by the frame 1.

Below the paper feed roller 9, a pinch roller 3 for pressing the recording paper 11 against the paper feed roller 9 and sandwiching the recording paper 11 with the paper feed roller 9 is rotatably supported by a shaft 31. There is. The shaft 31 is biased by a spring portion 32 formed on the chassis 2 as shown in FIGS. 7 and 9, and the pinch roller 32 is pressed against the paper feed roller 9 by this bias.

On the other hand, reference numeral 7 in FIGS. 5 and 6 denotes a stepping motor (hereinafter abbreviated as a motor) which is a common drive source for the carriage drive mechanism and the paper feed mechanism. The motor 7 is fixed to the lower surface of the chassis 2 fixed to the frame 1. By driving the motor 7, the timing belt 6 travels via a driving force transmission system, which will be described later, and the carriage 5 connected to the timing belt 6 is moved in the C and D directions. Further, the paper feed roller 9 is rotated by the drive of the motor 7 via a driving force transmission system described later, and is inserted between the paper feed roller 9 and the pinch roller 3 from the paper insertion port 10 formed on the upper surface of the frame 1. Recording paper
11 is sent to the platen 12 side.

Next, details of the structure of the driving force transmission system of the carriage driving mechanism and the paper feeding mechanism will be described with reference to FIGS.

First, as shown in FIG. 10, a belt drive pulley (hereinafter abbreviated as drive pulley) 25 and a worm gear 26 are fixed to the output rotary shaft 7a of the motor 7 as the drive source of both mechanisms. The drive pulley 25 and the worm gear 26 can be integrally formed. Then, as shown in FIG. 7, the drive pulley 25 and the worm gear 26 face the chassis 2 to which the motor 7 is fixed.

Further, as shown in FIGS. 7 and 8, three idler pulleys (driven pulleys) are provided on the chassis 2 together with the drive pulley 25.
28A to 28C are rotatably provided. The timing belt 6 is stretched by being in contact with and meshing with the four pulleys 25, 28A to 28C.

The structure of the timing belt 6 is as shown in FIGS. 1 (A) and 1 (B). That is, teeth are formed on the inner surface of the timing belt 6 at a predetermined pitch. The cross-sectional shape of each tooth along the belt length direction corresponds to the cross-sectional shape of the teeth of the pulleys 25, 28A to 28C, and is substantially trapezoidal close to a rectangle. And, a code is provided on the inner surface of the timing belt 6.
As shown by 6a, the toothless portion is provided over a predetermined length.

Here, the point different from the conventional one is that the tooth 6c located at the right end of the toothless portion 6a in FIG. Is formed in. The action due to the shape of the tooth 6c will be described later.

Further, at a predetermined position on the outer side surface of the timing belt 6, a convex portion 6b for projecting the coupling position of the carriage 5 to the belt 6 at a predetermined position is projected. In contrast to this
As shown in Fig. 11, a groove 5a is formed in the center of the front of the carriage 5.
Is provided. By fitting and fixing the convex portion 6b of the timing belt 6 into the groove 5a, the carriage 5
And the timing belt 6 are connected in a predetermined positional relationship.

On the other hand, as a structure of a driving force transmission system of the paper feeding mechanism, a worm wheel 26 rotatably driven by the motor 7 is meshed with a worm wheel 22 shown in FIGS. 7 and 8. As shown in FIG. 8, the worm wheel 22 is rotated by the worm gear 26 in the direction A or the direction B, so that the worm wheel 22 is driven by E.
Although it rotates in the F direction or the F direction, only the rotational driving force of the worm wheel 22 in the F direction is transmitted to the shaft 21 of the paper feed roller 9 by the following structure.

That is, the worm wheel 22 is supported by the arbor 23 fitted to the shaft 21 via the spring clutch 24 as shown in FIG. Spring clutch (not shown in detail)
One end of 24 is locked to the worm wheel 22. Therefore, the spring clutch 24 rotates integrally with the worm wheel 22, but when the worm wheel 22 rotates in the E direction in FIG. Therefore, the rotation of the worm wheel 22 is not transmitted to the shaft 21. On the other hand, when the worm wheel 22 rotates in the F direction, the spring clutch 24 engages the arbor 23, and the rotational driving force of the worm wheel 22 is transmitted to the shaft 21 via the spring clutch 24 and the arbor 23, and The feed roller 9 is rotated.

Next, the operations of the carriage drive mechanism and the paper feed mechanism having the above-described configurations will be described.

First, in the state before the start of recording, the carriage 5 is moved to the home position shown in FIG. 2 (B) and stopped. When the carriage 5 reaches the home position, the corner portion of the carriage 5 shown by reference numeral 5b in FIG. 8 contacts the home position sensor 14 as shown in FIG. 2 (B), and the state is detected.

When recording from this state, a drive signal (shift signal) is applied to the motor 7, and the drive pulley 25 is driven by the drive of the motor 7.
The worm gear 26 is rotated in the A direction in FIG. Here, the worm wheel 22 is rotated in the E direction by the worm gear 26. However, as described above, the rotation in the E direction is not transmitted to the shaft 21, the paper feed roller 9 does not rotate, and the recording paper 11 is fed. Absent.

On the other hand, the rotation of the drive pulley 25 in the A direction causes the timing belt 6 to rotate clockwise in FIG.
Is moved in the direction. During this period, a drive signal corresponding to the print data is applied to the print head 8 in synchronization with the shift signal of the motor 7, and the print head 8 is driven. For example, as an inkjet head, ink droplets are ejected to form one line in a dot matrix pattern. Is recorded.

Next, when the recording of one row is completed, the motor 7 is driven in the reverse direction, and the drive pulley 25 and the worm gear 26 are rotated in the B direction in FIG. In this case, the worm wheel 22 is rotated in the F direction by the worm gear 26, and this rotation is transmitted to the shaft 21 as described above, and the paper feed roller 9 is rotated in the F direction, so that a predetermined amount corresponding to the pitch between lines is obtained. The paper is fed and a line feed is made.

When the drive pulley 25 rotates in the B direction, the timing belt 6 runs counterclockwise in FIG.
Direction, and a carriage return is made. In this way, a line feed of paper is made at carriage return. Then, by repeating the above operation, a plurality of lines are recorded.

Next, the continuous paper feeding operation performed before the start of recording or after the end of recording will be described.

1A and 2A show the positional relationship between the timing belt 6 and the drive pulley 25 and the positional relationship between the carriage 5 and the frame 1 during the above-described recording operation or carriage return operation. . On the other hand, FIG. 1 (B) and FIG. 2 (B) show the respective positional relationships during continuous paper feeding.

As is clear from these figures, the recording operation or the carriage return operation is performed while the toothed portion of the timing belt meshes with the drive pulley 25 and the carriage 5
Is performed without being in the home position. On the other hand, in the continuous paper feeding operation, the carriage 5 is at the home position as shown in FIG. 2 (B), abuts against the wall 1b on the right side of the frame 1 in the drawing, and the timing is changed as shown in FIG. 1 (B). It is performed in a state where the toothless portion 6a of the belt 6 is in contact with the drive pulley 25. That is, the positional relationship is such that when the carriage 5 is moved to the home position, the toothless portion 6a of the timing belt 6 contacts the drive pulley 25.

During the continuous paper feeding operation, the drive pulley 25 and the worm gear 26 are continuously driven to rotate in the B direction in the states shown in FIGS. 1 (B) and 2 (B). In this case, the timing belt 6 tries to travel counterclockwise in the figure due to the frictional force acting between the drive pulley 25 and the toothless portion 6a of the timing belt 6, but the carriage 5 contacts the wall 1b of the frame 1. Therefore, it is blocked, the drive pulley 25 idles with respect to the timing belt 6, and the carriage 5 is forcibly stopped at the home position. On the other hand, worm gear
By rotating 26 in the B direction, the paper feed roller 9 is rotationally driven as described above, and the recording paper 11 is continuously fed.

Next, when the recording operation is performed after the continuous paper feeding operation is completed, the drive pulley 25 is rotationally driven in the A direction from the states of FIGS. 1 (B) and 2 (B). The timing belt 6 runs clockwise in the figure due to the frictional force between the toothless portion 6a of the timing belt 6 and the drive pulley 25. In this case, since the carriage 5 moves in the C direction and moves away from the frame wall 1b, its movement is not restricted, the drive pulley 25 does not idle with respect to the timing belt 6, and the timing belt 6 rotates clockwise due to frictional force. To run.

Then, as shown in FIGS. 3A to 3C, after the timing belt 6 is slightly moved in the direction of arrow G by the frictional force, the tooth 6c positioned at the end of the toothless portion 6a is driven by the drive pulley 25.
Tooth 25a of the drive pulley 25, and the tooth following the tooth 6c sequentially meshes with the tooth 25a of the drive pulley 25 to transmit the driving force by the engagement of the toothed portion of the drive pulley 25 and the timing belt 6 as described above. Then, the carriage 5 can be moved in the C direction to perform the recording operation.

Here, as shown in FIGS. 3A to 3C, the timing belt 6 moves in the G direction with respect to the drive pulley 25, and the tooth 6c at the end of the toothed portion meshes with the tooth 25a of the drive pulley 25. In doing so, since the tooth 6c has a triangular cross-sectional shape, the ratio of the tooth 25a of the drive pulley 25 riding on the tooth 6c is extremely small compared to the conventional case.

That is, the tooth tip of the tooth 6c is a line, and the area is extremely small, and the ratio of the tooth tip of the tooth 25a of the drive pulley 25 overlapping this tooth tip is significantly smaller than the overlapping rate of the conventional flat tooth tips. . Then, as shown in FIG. 4, the tooth 25a of the drive pulley 25 comes into contact with the slope 6d of the tooth 6c on the side of the toothless portion 6a or the ratio of contact with the slope 6e on the side of the toothed portion.

Then, as shown in FIG. 4, when the tooth tips of the teeth 25a of the drive pulley 25 contact the slope 6d, the timing belt 6 moves the slope 6d.
At a portion of the drive pulley 25, a reaction force in the direction of the arrow I is received from the tooth 25a of the drive pulley 25, and the tooth 25a of the drive pulley 25 is slid down from the slope 6d. The tooth 25b next to 25 comes into contact with the slope 6e on the opposite side of the tooth 6c.

Here, the slope 6d of the tooth 6c is a gentle slope, but the slope 6e
Is a slope corresponding to the corresponding slope (slope opposite to the toothless portion 6a) 6e ′ of the other tooth (reference numeral 6f in FIG. 4) of the toothed portion,
The steep slope is nearly vertical to the main body of the timing belt 6. Also, the slope 6e of the tooth 6c and the corresponding slope of the next tooth 6f
The distance 6e 'is the same as the tooth pitch P of the timing belt 6 as shown in FIG.

In this way, the driving pulley 25
When the teeth 25a of the drive belt 25 come into contact with and mesh with each other, the positional relationship between the timing belt 6 and the drive pulley 25 is such that the teeth 6a of the timing belt 6 and the following teeth 6f of the teeth 6c of the timing belt 6 are sequentially compared with the teeth 25a of the drive pulley 25. And will be able to mesh normally.

Thus, according to the present embodiment, the teeth 25a of the drive pulley 25 are moved when the recording operation is started after the continuous paper feeding operation is completed.
Can be prevented from riding on the teeth of the timing belt 6, and the occurrence rate of riding can be suppressed to a much lower level than in the past. Then, the timing belt 6 can be stably run at the time of shifting to the recording operation, and the carriage 5 can be stably moved to perform high-quality recording.

In the above, only one of the teeth facing the toothless portion of the toothed portion of the timing belt has a triangular cross-sectional shape, but it is conceivable that both of the end teeth have a triangular cross-sectional shape if necessary. To be Further, it is needless to say that the structure relating to the timing belt as described above is not limited to the carriage driving mechanism of the recording apparatus and can be similarly applied to a timing belt driving mechanism used as a driving mechanism of other various devices.

[Effects of the Invention] As is apparent from the above description, according to the present invention, a timing belt in which teeth of a predetermined shape are formed at a predetermined pitch is run by the rotational drive of a drive pulley that meshes with the belt. In a timing belt drive mechanism for moving a coupled driven body, the timing belt is provided with a toothless portion for idling the drive pulley with respect to the belt, and the toothless portion of the toothed portion of the belt is provided. Since the shape of at least one of the teeth facing both ends is different from the shape of the other teeth of the belt, the structure is such that the teeth of the drive pulley are hard to ride up. On the other hand, when running the belt from the toothless portion of the timing belt to the toothed portion, it is possible that the teeth of the drive pulley may ride on the teeth of the timing belt. It is possible to prevent this, and it is possible to obtain an excellent effect that the timing belt can be stably run and the driven body can be stably moved.

[Brief description of drawings]

1 (A) and 1 (B) respectively show the structure of the timing belt of the carriage drive mechanism of the recording apparatus according to the embodiment of the present invention, and the position with respect to the drive pulley during the recording operation, the carriage return operation, and the continuous paper feeding operation. Explanatory diagram showing the relationship, FIGS. 2 (A) and (B) are respectively FIG. 1 (A),
3B is an explanatory view of the positional relationship of the carriage with respect to the frame corresponding to FIG. 3B, and FIGS. 3A to 3C are explanatory views of the transition operation from the toothless portion to the toothed portion of the timing belt with respect to the drive pulley. FIG. 4 is an explanatory view of the action due to the cross-sectional shape of the teeth located at the end of the toothless portion of the timing belt,
FIG. 5 is a perspective view showing the structure of the main part of the recording apparatus main body of the embodiment, FIG. 6 is a sectional view of the main part of the recording apparatus main body, and FIG. 7 is a partially cutaway front view of the same main body. FIG. 8 is a partially cutaway top view of the recording apparatus main body, FIG. 9 is a bottom view of the recording apparatus main body, and FIG. 10 is a side view of a motor that is a drive source of a carriage driving mechanism and a paper feeding mechanism. FIG. 11 is a top view of the carriage of the recording apparatus, FIGS. 12A and 12B are explanatory views of the structure and operation of the timing belt of the carriage drive mechanism in the conventional recording apparatus, and FIGS. FIG. 14B is an explanatory view of the occurrence of running of the teeth of the driving pulley with respect to the teeth of the timing belt in the conventional example, and FIG. 14 is a diagram showing the running rate of running of the teeth related to the feed amount of the driving pulley. 1 ... Frame, 2 ... Chassis 3 ... Pinch roller, 5 ... Carriage 6 ... Timing belt 7 ... Stepping motor 8 ... Recording head, 9 ... Paper feed roller 11 ... Recording paper, 22 ... Worm wheel 24 …… Spring clutch, 25 …… Belt drive pulley 28A to 28C …… Idler pulley

Claims (2)

(57) [Claims] 1. A timing belt drive mechanism for moving a driven body connected to a timing belt, which has teeth of a predetermined shape formed at a predetermined pitch, by the rotational driving of a drive pulley that meshes with the belt. The timing belt is provided with a toothless portion for idling the drive pulley with respect to the belt, and at least one of the teeth of the toothed portion of the belt facing both ends of the toothed portion has a shape A timing belt drive mechanism characterized in that, unlike the other teeth of the belt, the teeth of the drive pulley are formed in a shape that makes it difficult for the teeth of the drive pulley to ride up. 2. A tooth of a timing belt other than the tooth is formed such that at least one of the teeth of the toothed portion of the timing belt facing both ends of the toothless portion has a substantially triangular cross-section along the belt length direction. 2. The timing belt drive mechanism according to claim 1, wherein the cross-sectional shape along the belt length direction is substantially rectangular.