JPS6398462A - Preventive mechanism for platen return - Google Patents

Abstract

PURPOSE:To maintain suitable printing quality by preventing a platen from being pulled back in a reverse rotary direction when the platen is stopped to be rotated, by engaging a lever component in the gear tooth of a driven gear when the platen does not pivot. CONSTITUTION:A stop lever 10 pivots in a rocking manner under the state of receiving a energizing force due to right and left energized springs 11a, 11b around the output axis 9 of a solenoid 8 during the positive rotation of a platen 4. Besides, in the case of a state in which the platen 7 is stopped to be rotated, i.e., when a motor 1 as a blank form feed power source is stopped to be driven, another drive signal is applied to the solenoid 8 and the lower 10 is driven. Then, both engaging detects 10a, 10b are engaged between the tooth 4a of a driven gear 4 and the driven gear 4 is prevented from returning in the reversal rotary direction. That is, in order to prevent the platen 7 from returning in the reversal rotary direction by pulling due to the weight or tension of the blank form when the platen 7 is stopped to be rotated, the stop lever 10 is positioned to be fixed by the working of the solenoid 8.

Description

Detailed Description of the Invention Technical Field The present invention relates to a platen return prevention mechanism, and more particularly to a cylindrical platen return prevention mechanism that backs up printing and feeds paper using a gear fixed to a motor shaft of a drive source and a power transmission mechanism engaged with the gear in a printer. This invention relates to a mechanism for preventing reverse rotation of a platen.

Conventional technology Conventionally, in a paper feed device of a printer, a cylindrical platen is rotated by a rotation transmission means such as a gear train fixed to the output shaft of a paper feed drive motor to back up printing and feed the paper. When the platen is not being rotated, the platen is usually fixed by applying a hold current.

However, in such a conventional printer paper feeding device, when the bold current is applied while the platen is not rotating, the platen is pulled back in the reverse rotation direction due to the influence of the weight and tension of the paper. As a result, there is a problem in that the rotation of the drive motor becomes uneven, resulting in deterioration of printing quality due to misalignment of the matrix and the like.

OBJECT OF THE INVENTION Therefore, the present invention was made to solve this conventional problem, and when the platen rotation is stopped during printing,
The purpose of the present invention is to provide a platen return prevention mechanism for a printer that maintains appropriate print quality by preventing the platen from being pulled back in the reverse rotation direction due to the weight and tension of paper.

Structure of the Invention In order to achieve the above object, the platen return prevention mechanism of the printer according to the present invention includes a driven gear that is integrally fixed to the platen rotating shaft and rotates as the platen rotates, and a lower part of the driven gear that is engaged with the driven gear. The apparatus is characterized in that it includes a removable lever member and a control means for engaging the lever member with the teeth of the driven gear when the platen is not rotating to prevent reverse rotation of the platen.

Embodiment An embodiment of the platen return prevention mechanism for a printer according to the present invention will be described below.

In FIG. 1, reference numeral 1 indicates a motor as a power source for paper feeding, 2 indicates an output shaft of this motor 1, 3 indicates a driving gear fixed to the output shaft 2, and 12 indicates that the rotation of this driving gear 3 drives intermediate gears 5, 6, etc. This is a gear that transmits data at a predetermined gear ratio. This gear 1
The motor 2 is integrally connected and fixed to the end of the rotating shaft of the platen 7, and the rotation of the motor 1 is transmitted to the platen 7 at a predetermined reduction ratio via each gear train. Further, the platen rotating shaft is provided with a driven gear 4 that is integrally fixed to the shaft and rotates as the gear 12 rotates.

Further, numeral 8 indicates a rotary solenoid type driving means.

On the other hand, 10 is a locking lever that is integrally connected and fixed to the end of the output shaft 9 of the drive means 8 and rotates in a rocking manner;
A pair of left and right engaging claws 10a, 10b expanded into a 7-shape
is adapted to engage with the teeth 4a of the platen side driven gear 4. That is, this locking lever 10 prevents the platen 7 from returning in the reverse rotation direction when stopped by both engaging pawls 10a and 10b engaging with the teeth 4a of the driven gear 4 as shown in FIG. This serves as a means of returning the platen. Also, 1
Numerals 1a and 11b are biasing springs that rotate and bias the pair of engagement claws 10a and 10b around the output shaft 9 in order to maintain them in a neutral position.

Next, the operation of the above embodiment will be explained.

When one line of printing is completed on the paper (not shown) set on the platen 7, the motor 1 drives the platen 7 in the direction of arrow A1 at the required rotational speed to move the paper to the next line. Rotate.

At this time, the pair of engaging claws 10a of the locking lever 10.

The solenoid 8 is driven so that only one side 10a of the gears 10b engages with the teeth 4a of the driven gear 4. Therefore, the engaging pawl 10a is in contact with the outer circumferential surface of the tooth 4a, so that the rotation of the driven gear 40 is not restricted. That is, platen 4
During normal rotation, the locking lever 10 rotates around the output shaft 9 of the solenoid 8 while receiving the biasing force from the left and right biasing springs 11a and 11b.

On the other hand, when the platen 7 is in a state where the rotation is stopped, that is, when the motor 1 as the paper feeding power source is stopped driving,
Another drive signal is applied to solenoid 8 to drive lever 10 to the position shown in FIG. Therefore,
Both engaging pawls 10a, 10b engage between the teeth 4a of the driven gear 4, as shown in FIG. 2, to prevent the driven gear 4 from returning in the reverse direction of rotation indicated by arrow A2. That is, once the platen 7 has stopped rotating, the solenoid 8 is operated to position the locking lever 10 at the position shown in FIG. Fix it.

As described in detail, the platen return prevention mechanism of the printer according to the present invention prevents the paper from returning due to the weight or tension of the paper while the bold current is applied to the motor of the paper feed power source and the rotation of the platen is stopped. In order to prevent the platen from rotating backwards and being returned due to the impact, it prevents uneven rotation of the motor used to rotate the platen forward and allows the paper to be fed at a normal feeding pitch, improving print quality. It is possible to make it "direct".

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a paper feeding mechanism of a printer according to the present invention, and FIG. 2 is a diagram showing an operation mode of the mechanism shown in FIG. 1 when the platen is stopped. Explanation of symbols of main parts 4... Driven gear 7... Platen 8... Solenoid 10... Locking lever

Claims (1)

[Claims] a driven gear that is integrally fixed to the platen rotating shaft and rotates as the platen rotates; a lever member that can be freely engaged and detached from the teeth of the driven gear; and a lever member that connects the lever member to the driven gear when the platen is not rotated. a control means that engages with teeth of the platen to prevent reverse rotation of the platen.