JP2530929Y2 - Pinch roller opening / closing mechanism of printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a printer that accurately conveys printing paper by using, for example, a platen and a pair of pinch rollers arranged on the upstream and downstream sides in the paper conveying direction. The present invention relates to a pinch roller opening / closing mechanism of a printing apparatus, and more particularly to prevention of indentation of a platen.

[Conventional technology]

FIG. 4 is a view showing a pinch roller opening / closing mechanism of a conventional printer. In the figure, (1) is a platen, (2),
(2) a pair of pinch rollers arranged on the upstream side and the downstream side with respect to the sheet transport direction, (3) a manual operation lever integrally formed with a cam portion (3a) for opening and closing the pinch roller,
(4) and (4) are rotatably supported by arm fulcrums (6) and (6), and rotatably support the upstream and downstream pinch rollers (2) and (2), respectively. A pair of arms (5) are mounted between the arms (4) and (4) and press springs pressing the upstream and downstream pinch rollers (2) and (2) against the platen (1); 3b) is a lever shaft which rotatably supports the manual operation lever (3).
In the drawing, (P) is a printing paper sandwiched between the upstream and downstream pinch rollers (2), (2) and the platen roller (1) at a constant pressure.

Next, the operation will be described. As shown in FIG. 4, the upstream and downstream pinch rollers (2) and (2) are normally constantly pressed by the platen (1) to perform a printing operation by the pressing spring (5).

Only when a trouble such as paper jam occurs, the cam portion (3a) is rotated by operating the manual operation lever (3), and the arms (4) and (4) are supported by the arm fulcrums (6) and (6). When opened, the pinch rollers (2), (2) on the upstream side and the downstream side are separated from the platen (1), and trouble handling, such as taking out the printing paper (P) in which a feeding error has occurred, is performed.

[Problems to be solved by the invention]

As described above, the pinch roller opening / closing mechanism of the conventional printing apparatus uses the pinch rollers (2), (2) because the upstream and downstream pinch rollers (2), (2) are normally always pressed against the platen (1). Pressing of (2) leaves imprints on the surface of the platen (1), which causes problems such as a decrease in print quality.

This invention was made in order to solve the above-mentioned problems, and the print quality was degraded due to indentations on the platen surface by automatically separating the pinch roller from the platen during standby other than during the printing operation of the printing device. It is an object of the present invention to obtain an inexpensive pinch roller opening / closing mechanism of a printing apparatus which can prevent the occurrence of the problem.

[Means for solving the problem]

The pinch roller opening / closing mechanism of the printing device according to the present invention includes:
A cam shaft for up / down operation of a head, which is provided through a one-way clutch so as to mesh with a drive source capable of rotating forward and backward, and for opening and closing a pinch roller provided via a one-way clutch which operates in reverse rotation to the one-way clutch. And a cam shaft for operating a pinch roller opening / closing cam shaft by a driving source in a series of printing operations, so that the pinch roller is separated from the platen during standby other than during the printing operation.

[Action]

In this invention, the operation of the head up / down operation cam shaft and the operation of the pinch roller opening / closing cam shaft are performed in a series of printing operations by forward / reverse rotation of the same drive source.

[Example of the invention]

An embodiment of the present invention will be described below with reference to FIGS. In the drawings, the same or corresponding parts as those of the conventional one are denoted by the same reference numerals, and description thereof is omitted. (7) is a drive gear driven by a drive motor (not shown) for moving the thermal head up and down, and (8) is a pinch roller opening / closing cam shaft (10) together with a one-way clutch (not shown).
A pinch roller opening / closing gear rotatably supported by the shaft and meshes with the drive gear (7). Reference numeral (9) denotes a head up / down operation gear rotatably supported by a head up / down operation cam shaft (11) together with a one-way clutch (not shown), and a driving gear (7).
Meshes with The camshaft (10) for opening and closing the pinch roller and the camshaft (11) for moving the head up and down are either one-way clutch, depending on whether the drive gear (7) is rotated forward or backward by the drive motor. Only the camshaft (10) or (11) rotates.

Here, a drive motor having a structure capable of normal and reverse rotation is used.

 Next, the operation will be described.

FIG. 2 shows that the upstream and downstream pinch rollers (2) and (2) are separated from the platen roller (1) by the rotation of the pinch roller opening / closing cam shaft (10) driven by the drive gear (7). This is a so-called print standby state.

FIG. 1 shows that the upstream and downstream pinch rollers (2) and (2) are pressed against the platen roller (1) by the rotation of the pinch roller opening / closing cam shaft (10) driven by the drive gear (7). This is a state during a so-called printing operation, in which the printing paper (P) is nipped and transported at a constant pressure by the upstream and downstream pinch rollers (2), (2) and the platen roller (1).

In the forward rotation of the drive motor, the cam shaft (1
The one-way clutch of (0) transmits the driving force but slips in the reverse rotation. On the other hand, the head up / down operation cam shaft (11) transmits the driving force by the reverse rotation of the drive motor and slips by the forward rotation.
Accordingly, by controlling the forward and reverse rotations of the drive motor in a series of printing operations, the pinch rollers (2), (2) are opened and closed and the heads are moved up and down via the pinch roller opening and closing cam shaft (10). The operation can be performed by the same drive motor.

Pinch roller opening / closing cam shaft (10) as in the above embodiment
When a drive motor for head up / down operation is shared as a drive source for the device, the device becomes inexpensive.

In the above embodiment, the pinch roller opening / closing cam shaft (10) is arranged between the arm fulcrums (6) and (6) and the upstream and downstream pinch rollers (2) and (2). As shown in the figure, the same effect as in the above embodiment can be obtained even if the pinch roller opening / closing camshaft (10) is arranged on the tip side of the arms (4), (4).

[Effect of the invention]

As described above, according to the present invention, at the time of standby other than during the printing operation, the operation of separating the pinch roller from the platen is performed in a series of the printing operation with the same driving source as the head up-and-down operation. There is an effect that a mechanism capable of preventing a decrease in printing quality due to indentation can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a printing operation of a pinch roller opening / closing mechanism according to an embodiment of the present invention, FIG.
FIG. 3 is a view showing a state during printing according to another embodiment of the present invention;
FIG. 4 is a view showing a conventional pinch roller opening / closing mechanism. In the figure, (1) is a platen, (2) and (2) are pinch rollers, (3a) is a pinch roller opening / closing cam section, (7)
Denotes a drive gear, and (8) denotes a pinch roller opening / closing gear. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-222373 (JP, A) JP-A-61-71458 (JP, U) JP-A-59-112660 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] A pair of pinch rollers disposed on an upstream side and a downstream side of a platen in a sheet conveying direction, a pair of arms rotatably supporting the respective pinch rollers, and an arm between the respective arms for opening and closing the arms. A pinch roller opening / closing cam section for bringing the pinch roller into and out of contact with the platen, a drive source capable of rotating forward and reverse, and
A cam shaft of the pinch roller opening / closing cam portion provided via a direction clutch, and a head up / down operation provided in mesh with the drive source via a one-way clutch which operates in a reverse rotation to the one-way clutch. A cam shaft, the pinch roller opening / closing cam shaft and the head up / down operation cam shaft are operated by forward / reverse rotation of the one drive source in a series of printing operation, and the operation is performed during a printing operation. A pinch roller opening / closing mechanism for a printing apparatus, wherein the pinch roller is separated from the platen during standby.