JPS60264270A - Printer - Google Patents

Abstract

PURPOSE:To enable the reduction in noise and vibration, by providing a third friction wheel between the friction wheel attached to a stepping motor and that attached to a platen shaft and providing a wt. to the guide plate, lever and spring of the bearing of said third friction wheel. CONSTITUTION:When a platen 8 is driven by a stepping motor 20, a wt. 12 is moved to the direction of a shaft 15. A movable friction wheel 16 is pressed to a friction wheel 13 and contact pressure sufficient for rotating the platen 8 is obtained, and the friction wheel 13 and the movable friction wheel 16 are rotated without generating slip to make it possible to rotate the platen 8. At the time of manual driving, the wt. 12 is moved to the direction spaced part from the shaft 15 so as to move a bearing 17 to the direction pushed in to the side of a spring 19. The bearing 17 is stopped at a place where force is well balanced. The contact pressure between the movable friction wheel 16 and the friction wheel 13 is lowered by the movement of the bearing 17 and torque is not transmitted to the side of the stepping motor 20 by the slip of the friction wheels and no discontinuous torque is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printer that feeds sheets by rotating a platen with a step motor.

[Technical background of the invention and its problems]

A conventional printer was as shown in FIG. In other words, a platen 1 that rotates when paper is being fed, a chassis 3 that supports the platen 1 via a bushing 2, a gear 4 fixed to the shaft of the platen 1, and a manual drive that rotates the platen 1 when setting paper in the printer. A knob 5 fixed to the shaft of the platen 1 to rotate the platen 1, a step motor 6 that rotates the platen 1 during feeding and keeps the platen 1 from rotating except during feeding, and the torque of the step motor 6. and an idler gear 7 that transmits the information to the gear 4.

In a printer with this configuration, when setting paper, the knob 5 is manually rotated to wind the paper onto the platen 1. At this time, the step motor 6 is operated to rotate one step angle as the rotation angle increases, as shown in FIG. A holding torque is generated in which the direction of the torque changes discontinuously as one cycle.

Considering the discontinuity point of this discontinuous torque, before the discontinuity point the holding torque is in the direction of returning the manual rotation, but after the discontinuity point it changes to the direction of advancing the rotation, so the rotation of the platen l is not intermittent, and furthermore, due to the intermittent torque acting between the gear 4 and the idler gear 7, a sharp force is applied to the platen 1 in the direction perpendicular to the rotation axis in synchronization with the discontinuous point of the holding torque. works.

In addition, the bushings fitted into the grooves of the chassis 3 are loosely fitted so that they can be easily removed for maintenance or other purposes. When a steep force is applied in the direction perpendicular to the rotation axis of platen 1 at a discontinuity point, bush 2
This has the disadvantage that the collision between the chassis 3 and the chassis 3 generates noise.

[Purpose of the invention]

The present invention was made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a printer with low noise and low vibration.

[Summary of the invention]

The present invention includes a friction wheel and a movable friction wheel in the mechanism for transmitting the torque of the step motor 6 to the platen 1, so that the torque when manually rotating the platen 1 is not transmitted to the step motor 6, and the step motor This printer has a function to prevent the generation of discontinuous torque caused by 6.

〔Effect of the invention〕

According to the present invention, it is possible to reduce noise and vibration generated when the platen knob 5 is manually rotated when setting paper.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a printer according to the present invention. In the code in the same figure, 8 is the platen, 9 is the bush,
10 is a chassis, 11 is a lever attached to the chassis 10 via a shaft 15, 12 is a weight, 13 is a friction wheel fixed to the shaft of the platen 8, 14 is a knob fixed to the shaft of the platen 8, and 15 is a lever fixed to the shaft of the platen 8. A lever 11 is attached to the chassis 10, a shaft serving as a fulcrum for the lever 11, 16 a movable friction wheel, 17 a bearing that moves along the guide of the mounting plate 18, 18 a guide plate for the bearing 17, and 19 a guide plate 18. spring attached to, 20
indicates a step motor.

In this configuration, when the platen 8 is driven by the step motor 20, the weight 12 is moved in the direction of the shaft 15. At this time, the movable friction wheel 16 is pressed against the friction wheel 13 by the action of the bearing 17 which moves on the guide plate 18 due to the repulsive force of the spring 19. As a result, sufficient contact pressure between the friction wheels is obtained to rotate the platen 8 by the step motor 20, and the friction wheels 13 and the movable friction wheels 16 rotate without slipping, making it possible to rotate the platen 8.

On the other hand, when manually driving the platen 8, the weight 12
is moved in the direction opposite to the axis 15.

The tip of the lever 11 uses the shaft 15 as a fulcrum and moves the bearing 17 moving on the guide plate 18 in the direction of pushing it into the spring 19 side. It comes to rest at a point where the force exerted by the tip on the bearing 17 is balanced. The contact pressure between the movable friction wheel 16 and the friction wheel 13 decreases due to the movement of the bearing 17, and the torque when turned manually is transferred to the step motor 20 side due to the force between the friction wheel 13 and the movable friction wheel 16. is not transmitted, and as a result no discontinuous torque is generated.

FIG. 2 is a simplified view of the movement of the lever 11 and the movement of the movable friction wheel 16 when viewed from the side. The solid line shows when the platen 8 is driven by the step motor 20, and the dotted line shows when the platen 8 is driven manually. Each lever 11 when driving the platen 8
and shows the position of the movable friction wheel 16.

Note that if a material with a large damping effect is used for the friction wheel 13 and the movable friction wheel 16, an effect of reducing noise and vibration generated when the platen 8 is rotated by the step motor 20 can be expected.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a printer according to the present invention;
Figure 2 shows the movable friction wheel 16 when viewed from the side direction of Figure 1.
FIG. 3 is a diagram showing a simplified movement of the lever 11, and FIG. 3 is a perspective view showing a conventional printer. FIG. 4 is a diagram showing the quiet torque of the step motor. 8...Platen, 11...Lever, 12...Height, 13...Friction wheel, 14...Knob, 15...Shaft,
16... Movable friction wheel %17... Bearing, 18... Guide plate, 19... Subling, 20... Step motor. (7) 3 Figure 1

Claims (1)

[Claims] In a printer that has a mechanism that rotates the platen with a step motor to advance the platen, there is a first friction wheel attached to the step motor, a second friction wheel attached to the platen shaft, and a friction wheel between these two friction wheels. A printer comprising a third friction wheel located in between, a guide plate for guiding a bearing attached to the third friction wheel, and a lever, spring, and weight for controlling the movement of the bearing.