JPS5829690A - Motor fitting structure for printer - Google Patents

Abstract

PURPOSE:To obtain a motor fitting structure for a printer, which is needed for adjustment and capable of automatically eliminating back-lash by using a system in which a rocking plate to fix a motor is energized through a cam by an elastic part and the toothed wheel of the motor is pressed on a follow-gear at all times. CONSTITUTION:A motor toothed wheel 28 is engaged with a follow gear 27 fixed to the center shaft 25 of a drive pulley 23. A rocking plate 31 attached with a motor 29 is attached in a rocking manner to the periphery of a stud 32, and a cam 33 is pressed on the other end side of the rocking plate 31. The cam 33 is rotatably provided around a fixed pin 34 and is provided with a clockwise turning tendency by an elastic part 35. The contact portion between the cam 33 and the rocking plate 31 is so formed tha the contact line at the contact point P can pass the rocking center of the rocking plate 31 and normal (m) can pass almost the turning center of the cam 33. Thus, the motor toothed wheel 28 is always pressed on the follow gear 27.

Description

Detailed Description of the Invention This invention meshes a motor gear with a driven gear, transmits the rotation of the motor to the driven gear, and transmits the rotation of the driven gear to the carriage via a flexible mediating member such as a wire belt. ,
Regarding printers that print by moving the carriage,
More specifically, the present invention relates to a motor mounting structure that automatically eliminates backlash in meshing between the motor gear and the driven gear.

Conventionally, printers of the type described above have been made, for example, as shown in FIG. This motor is designated by the reference numeral l in the figure, and is fixed via a bracket 2 to a side plate 3, only a portion of which is shown. A motor gear 5 is attached to the motor shaft 4 of the motor l, and the motor gear 5 is connected to a driven gear 6.
meshes with

The driven gear 6 is pivotally supported at one end of the stay 7, and a drive pulley 8 is provided coaxially therewith. One of the bending media members 9, such as a wire or a belt, is hung on the drive pulley 8. The other end of the deflection mediating member 9 is hung on a driven pulley lO. The driven pulley 10 is pivotally supported at the other end of the stay 7 described above. The above-described bending mediating member 9 is attached to the carriage 11. The carriage 11 is supported by a support shaft (not shown),
It is moved along the shaft in a direction parallel to the stay 7. Such a carriage 11 is equipped with type, a printing hammer, and the like.

Now, when the motor 1 operates, the rotation of the motor 1 is transmitted to the driven wheels 6 via the motor gear 5, and the driving pulley 8 on the same axis rotates. The rotation of the drive pulley 8 is transmitted to the carriage 11 via the bending mediating member 9, and moves the carriage 11 to a predetermined position. Thereafter, for example, a printing hammer of the carriage 11) strikes the type to print on the paper on the platen.

By the way, in a printer as shown in FIG. 1, if there is backlash between the motor gear 5 and the driven gear 6, the position of the gear ridge 11 will fluctuate to that extent and will not be accurately determined, resulting in poor print quality. There were drawbacks. This will be explained with reference to FIG.

If the diameter of the portion of the drive pulley 8 that contacts the bending mediating member 9 is: , the pitch diameter of the driven gear 6 is 02, and the backlash between the motor gear 5 and the driven gear 6 is ΔB, then the carriage 11 The variation ΔB in the digit l is expressed by the following formula.

ΔS−ΔBxD, /D.

In other words, when there is backlash ΔB, the position of the carriage 11 changes by ΔB calculated from the above formula, and the printing position accuracy deteriorates accordingly.Therefore, conventionally, when installing the motor 1%, the motor gear 5 is changed. Adjustment was made so that backlash ΔB would not occur by moving in the direction indicated by the arrow in FIG.

However, since the adjustment is performed while checking the backlash visually, etc., there is a drawback that the adjustment takes time.

In addition, it is difficult to make the pitch circle of a gear perfectly circular, and it is also difficult to make it without eccentricity.
It was not possible to completely eliminate backlash, and there was a drawback that print quality varied. Furthermore, when used for a long period of time, backlash may occur due to wear etc., which has the disadvantage of requiring readjustment later.

Therefore, this invention automatically eliminates backlash and
It is an object of the present invention to eliminate the need for adjustment and to prevent backlash from occurring all the time, so that constant printing quality can be obtained.

The feature of this invention is that the motor gear is meshed with the driven gear in a double-coupled manner, and the rotation of the driven gear is transmitted to the driven gear, and the rotation of the driven gear is transmitted to the flexible gear of a wire belt, etc. In a printer that prints by moving the carriage through an intermediary member, the motor is fixed to a rocking plate, and the rocking plate is swung around one end by a side plate that supports the central axis of the driven gear. At the same time, a cam is rotatably attached to the side plate, and the cam is biased with an elastic member and pressed against the other end of the rocking plate to press the motor gear against the driven gear, so that the contact between the rocking plate and the cam is always maintained. Does the tangent at the contact point pass approximately through the center of oscillation of the oscillation plate, and does the normal line approximately pass through the center of cam rotation? : The motor mounting structure consists of a rocking plate and a cam shaped like this.

Below, a motor mounting structure according to the present invention will be explained in detail based on an embodiment of the present invention shown in FIG. 1 In FIG. 3, the reference numeral 20 indicates a carriage, and although not shown, type, printing hammers, etc. are loaded thereon. and,
Similar to the printer shown in FIG. 1, printing is performed by hitting the type with a printing hammer at a predetermined position. Such a carriage 2
0 is supported by a support shaft 21 and moved along the support shaft 21 under tension by a deflection mediating member 22 . A wire belt or the like is used as the bending mediating member 22, and a hook is passed between the driving pulley 23 and the driven pulley 24. The center shaft 25 of the drive pulley 23 is supported by a side plate 26, and a driven gear 27 is mounted on the center shaft 25.
are attached coaxially and rotated together with the drive pulley 23. A motor gear 28 meshes with the driven gear 27 . The motor gear 28 is mounted on a motor shaft 30 of a motor 29. The motor 29 is attached to the swing plate 31. The swing plate 31 is aligned with the side plate 26 described above,
It is mounted around a stud 32 erected on the side plate 26 so as to be able to swing freely around one end.

A cam 33 is pressed against the other end side of such a swing plate 31. The cam 33 is also provided to be rotatable about a fixing pin 34 erected on the side plate 26, and is normally given the habit of rotating clockwise in the figure by an elastic member 35. The elastic member 35 has one end attached to the cam 33 and the other end attached to a pin 36 erected on the side plate 26 . In this invention, as shown in FIG. 4, in the contact area between the cam 33 and the swing plate 31, the tangent l at the contact point p always passes approximately through the center of swing of the swing plate 31 (i.e., the stud 32). , modulus@m is formed in such a shape that it passes approximately through the center of rotation of the cam 33 (that is, the fixing pin 34).

According to this invention, as described above, the rocking plate is biased by the elastic member via the cam and the motor gear is always pressed against the driven gear, so no adjustment is necessary, and even if the pitch of the motor gear or driven gear is Even if the gear is not a perfect circle or is eccentric, backlash can be automatically eliminated in the meshing between the motor gear and the driven gear.

Furthermore, backlash does not occur due to wear caused by long-term use, and backlash can be completely eliminated, so that printing quality can be kept constant.

In the embodiment described above, without using the cam 33,
Although the motor gear 28 can be pressed against the driven gear 27 even if the swing plate 81 is directly urged by the elastic member 35,
In this way, the rocking plate is not restricted by the cam and swings both clockwise and counterclockwise, so as the driven gear rotates, the motor gear approaches the center axis of the driven gear. Or move away. However, since the motor has a certain weight, once the motor gear has moved away, it cannot immediately return to its original position due to inertia. A backlash will occur.

However, according to this invention, the cam 33 is used, and the cam 33
and the shape of the contact portion of the rocking plate 31 at the contact point p.
Tangent line in! Since it is made so that the normal line m passes approximately through the center of rotation of the cam 83, and the normal line m passes approximately through the center of rotation of the cam 83, even if the motor gear 28 recedes from the central axis 25 of the driven gear 27, The swinging of the swinging plate 31 in the counterclockwise direction in the figure is suppressed by the cam 33, and the motor body 29 does not move, leaving only the motor shaft 30.

Therefore, due to the rotation of the driven gear 27, the motor gear 28
It is not affected by inertial force and can immediately return to its original position, and the motor gear 28 is always pressed against the driven gear 27, so that no backlash occurs between the two gears.

That is, as shown in FIG. 4, when the motor gear 28 located at the solid line position rotates, the driven gear 27 that meshes with the motor gear 28 also rotates. The motor gear 28 is an elastic member 35
Since the pitch circle of the driven gear 27 is not a perfect circle and is eccentric as shown in FIG. 4, the motor gear 28 is always pressed against the driven gear 27.
As 7 rotates, it eventually moves to the position indicated by the chain double-dashed line in the figure, which is closest to the central axis 25. At this time, the swing plate 31 and the cam 33 simultaneously move to the position indicated by the dashed line in FIG. 4, and come into contact at the contact point p'. The contact fjLl' at this contact point p' is also approximately the stud 3
2, and the modulus @m' also almost passes through the fixed pin 34. Therefore, the cam 33 prevents the swing plate 31 from swinging counterclockwise. Therefore, once the motor gear 28 is as close as possible to the central shaft 25, N! Even if the driven gear 27 rotates and returns to the solid line position M in the figure, it cannot return to the solid line position like the rocking plate 31. Therefore, the movement of the motor gear 28 is absorbed by the deflection of the motor shaft 30, as described above.

In the above embodiment, in order to prevent the cam 33 from being bitten by impact or the like, after the driven gear 27 is rotated once to determine the position of the swing plate 31, the fixing screws 37 and 3 shown in FIG.
8 may be tightened to fix the swing plate 31. The fixing screws 37 and 38 are connected to the long holes 39 and 40 of the swing plate 31.
and is screwed into the side plate 26.

The motor mounting structure shown in FIG. 3 is an embodiment of the present invention, and the motor mounting structure according to the present invention is applicable not only to printers of the type shown in FIG. This can be applied to all types of printers that print by moving the carriage by transmitting the information to the driven gear and to the carriage via the rotational bending member of the driven gear.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a conventional motor mounting structure in a printer. FIG. 2 is a schematic mechanical explanatory diagram illustrating how the carriage position changes when there is backlash between the motor gear and the driven gear in the motor mounting structure shown in FIG. 1. FIG. 3 shows a motor mounting structure showing one embodiment of the present invention, and is an enlarged perspective view showing a part of the space mechanism of the printer. Fourth
The figure is a schematic operational explanatory diagram illustrating the movement of each part in the motor mounting structure shown in FIG. 3. 28...Motor gear, 27...Driver gear, 29.°゛°°゛°°゛Motor...Bending medium member, 20...Carriage, 31...°...
Rocking plate, 25°゛°...center shaft, 26...side plate, 33...cam, 3 =...elastic member,
p-p'...Tangent, e/l'...Tangent, m"m'...Normal. Patent applicant Rico Co., Ltd. - Agent Patent attorney Medium Shunsuke Oo

Claims (1)

[Claims] The motor gear meshes with the driven gear, transmits the rotation of the motor to the driven gear, transmits the rotation of the driven gear to the carriage via a bending media member, and is installed in a printer that moves the carriage and performs printing. , the motor is fixed to a rocking plate, the rocking plate is attached to a side plate supporting the central shaft of the driven gear so as to be swingable about one end, and a cam is rotatably attached to the side plate; The cam is urged by an elastic member and pressed against the other end of the rocking plate to press the motor gear against the driven gear, so that the tangent at the contact point between the rocking plate and the cam is always approximately equal to the rocking plate. A motor mounting structure for a printer, wherein the rocking plate and the cam are formed in a shape such that the rocking plate and the cam pass through the rocking center of the cam, and the normal line approximately passes through the rocking center of the cam.