JPH0647862Y2 - Printer paper feed mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a paper feed mechanism of a printer that feeds recording paper one by one to a predetermined recording means.

[Conventional technology]

The paper feeding mechanism of the printer feeds the recording paper one by one to a predetermined recording device that records by thermal transfer or laser light.

By the way, as a conventional paper feed mechanism of this type, as shown in FIG. 8, a recording paper 3 on a tray 2 is pressed against a feed roller 4 arranged above by a spring 1, and the feed roller 4 is rotated by this rotation. There is one in which the recording paper 3 is sent out.

[Problems to be solved by the device]

However, in such a conventional paper feeding mechanism,
Since the spring force changes depending on the amount of the recording paper 3 on the tray 2, the recording paper 3 could not be pressed against the feed roller 4 with a constant pressure. That is, when the amount of the recording paper 3 is large, the spring 1 contracts more and the spring force becomes stronger. Therefore, the recording paper 3 is pressed against the feed roller 4 more than necessary, and when the recording paper 3 is small, the pressing force is insufficient. I ended up doing it.

For this reason, it has been difficult to reliably feed the recording sheets one by one, such as sending the recording sheets one at a time when the amount of recording sheets is large.

[Purpose of device]

The present invention has been made in view of the above point, and allows the recording paper to be accurately fed one by one by pressing the recording paper against the paper feed roller with a constant pressure regardless of the amount of the recording paper. , The operation such as holding down the drive lever when attaching and detaching the paper cassette is not required,
The loading operation of the paper feed cassette can be easily performed. An object is to provide a paper feed mechanism for a printer.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a drive lever that is freely rotated between a standby position and a position where a recording sheet is pressed against a feed roller, and a drive lever that is hooked at one end with the drive lever. The coil spring that biases the coil spring and the other end of the coil spring are slidable, and the link lever is slidable substantially parallel to the biasing direction of the coil spring. When the drive lever is rotated by abutting on the pin protruding from the drive lever and holding the drive lever at the standby position, and when the drive lever is rotated with the link lever slid in the direction to increase the biasing force of the coil spring, A line that connects the dynamic fulcrum and the point of action of the coil spring and a groove that slides the pin so that the biasing direction of the coil spring form an acute angle are provided. A feed roller always is obtained as pressed at substantially constant pressure.

[Action]

As described above, the present invention keeps the line connecting the rotation fulcrum and the action point at an acute angle with respect to the direction of the spring force. Therefore, when the displacement amount of the spring means is large, the rotation fulcrum and the spring force are perpendicular to each other. The distance becomes short, and when the displacement amount is small, the vertical distance becomes long.

Therefore, it becomes possible to maintain the torque of the drive lever, which is obtained by the product of the spring force proportional to the displacement amount of the spring means and the vertical distance, at a substantially constant value, and the recording paper is fed to the feed roller regardless of the amount of the recording paper. On the other hand, it can always be pressed with almost constant force.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows an outline of the periphery of the paper feed mechanism of the printer according to this embodiment. In the figure, 10 is a printer main body, and a thermal head 12 for performing thermal transfer printing is provided inside.
And platen 14 is provided. A recording paper cassette 20 containing a recording paper 18 is set in the cassette loading opening 16. A tray 22 on which the recording paper 18 is placed is provided in the recording paper cassette 20, and the tray 22 is moved up and down by a drive lever 24 described later.

A feed roller 26 is arranged in front of the thermal head 12 in the printer body 10, and the rotation of the feed roller 26 causes the recording paper 18 on the tray 22 to be fed one by one by friction.

FIG. 1 shows the detailed structure of the paper feed mechanism.

This paper feed mechanism includes the above-mentioned drive lever 24, a tension coil spring (hereinafter, simply referred to as “spring”) 27 that gives a rotational force to the drive lever 24, and a spring force of the spring 27 to the drive lever 24. The driven plate 28 for transmission, a link 30 for restricting the action direction of the spring force of the spring 27, and a crank plate 32 for driving the link 30.

Of these, the drive lever 24 is composed of a driven member 34 fixed to the driven plate 28 and an arc-shaped action portion 36 which comes into contact with the tray 22 and pushes up the tray 22, and the action portion is associated with the rotational movement of the driven plate 28.
36 is designed to move up and down.

The driven plate 28 is a thin plate shaped like a key, and one end of the driven plate 28 is rotatably supported by the rotation shaft 38. The rotary shaft 38 is inserted into the driven member 34 of the drive lever 24, and both ends thereof are fixed to the printer body 10. A spring is attached to the other end of the driven plate 28.
A pin 40 to which the end of 27 is hooked is implanted, and this pin 40 is inserted into the guide groove 42 of the link 30 and is slidable along this groove 42.

The shape of the driven plate 28 and the positional relationship between the rotary shaft 38 and the pin 40 are designed so that a substantially constant torque is applied to the drive lever 24 regardless of the amount of the recording paper 18. That is, the third
As shown in the figure, the angle θ formed by the line connecting the rotating shaft 38 and the pin 40 and the acting direction of the spring force is always within the range of about 30 ° <θ <90 °. The spring constant of the spring 27 and the initial expansion of the spring 27 (expansion of the spring 27 when the recording paper 18 is not on the tray 22) are the feed roller 26 and the recording paper.
The crimping force of 18 is set to be appropriate.

The link 30 and the crank plate 32 are connected by a pin 44 implanted in a part of the crank plate 32, and the rotation of the crank plate 32 causes the link 30 to move in the horizontal direction. In addition, a pin 46 for hooking the end of the spring 27 is planted in a part of the link 30.
Is drawn to the crank plate 32 side.

Next, the operation and action of the embodiment configured as described above will be described with reference to FIGS. 4 to 7.

First, in the standby state before the recording paper is set,
As shown in FIG. 4, the crank plate 32 is held so that the link 30 comes to the rightmost end, the spring 27 is in the most contracted state, and the action portion 36 of the drive lever 24 is lowered to a substantially horizontal position.

Next, a large amount of recording paper 18 is placed on the tray 22 of the recording paper cassette 20.
And place the recording paper cassette 20 in the cassette loading opening.
When it is inserted into the printer main body 10 from 16, the crank plate 32 is rotated 180 degrees clockwise in conjunction with this, and the setting of the recording paper is completed as shown in FIG.

That is, when the crank plate 32 rotates, the link 30 moves leftward and the pin 40 of the driven plate 28 is pulled leftward. On the other hand, the action portion 36 is pushed down by the tray 22 and lowered by the thickness of the recording paper 18, the drive lever 24 and the driven plate 28 rotate clockwise, and the pin 40 slides rightward along the guide groove 42. To do. As a result, the recording paper 18 on the tray 22 is
The spring 27 is pressed against the feed roller 26 with a force proportional to the extension amount of the spring 27.

At this time, since the angle θ formed by the line connecting the pin 40 and the rotating shaft 38 and the acting direction of the spring force is small, the spring 27 extends greatly and a large spring force is applied to the pin 40, while the rotating shaft 38
And the vertical distance r in the acting direction of the spring force becomes shorter.

When the recording paper 18 is fed, the feed roller 26 is rotated counterclockwise, and the recording paper 18 is fed one by one between the thermal head 12 and the platen 14 by friction.

After that, when the recording paper 18 on the tray 22 is reduced, the action portion 36 of the drive lever 24 rises as shown in FIG.
40 slides to the left and spring 27 contracts. As a result, the angle θ formed by the line connecting the pin 40 and the rotating shaft 38 and the acting direction of the spring force increases, and the spring force applied to the pin 40 decreases, while the action of the rotating shaft 38 and the spring force decreases. The vertical distance r in the direction becomes long.

Then, when the recording paper 18 is finally exhausted, the action portion 36 of the drive lever 24 rises to the highest portion as shown in FIG.
The line connecting 38 and pin 40 is almost vertical, that is, θ = 90 °.

As described above, in the paper feeding mechanism according to the present embodiment,
When the spring force is strong, the vertical distance r between the direction of the force and the rotary shaft 38 is short, and conversely, when the spring force is weak, the vertical distance r becomes long. Therefore, the product of the magnitude of the spring force and the vertical distance r is given. The torque of the drive lever 24 thus driven becomes a substantially constant value. Therefore, the force of the operating portion 36 of the drive lever 24 pushing up the tray 22 is also constant, and the recording paper 18 is pressed against the feed roller 26 with a substantially constant force regardless of the amount of the recording paper 18, so that the recording paper 18 is fed one by one. The paper is reliably fed.

Then, the recording papers 18 fed out one by one by the feed roller 26 are subjected to thermal transfer printing between the thermal head 12 and the platen 14, and then discharged to the outside of the printer body 10.

[Effect of device]

As described above, according to the present invention, the torque applied to the drive lever is substantially constant regardless of the amount of the recording paper, so that the recording paper can be pressed against the feed roller with a constant force. There is an effect that the paper can be reliably fed one by one. Further, when the link lever is slid in the direction in which the biasing force of the coil spring is weakened, the pin of the drive lever is received at one end of the groove.
There is no need for an operation such as holding down the drive lever when attaching or detaching the paper feed cassette, and there is an effect that the loading operation of the paper feed cassette can be easily performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing the construction of an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of a printer using the paper feeding mechanism according to the embodiment. FIG. 3 is an explanatory diagram for explaining the operation of the embodiment. 4 to 7 are side views showing the operation of the embodiment. FIG. 8 is a side view showing a schematic configuration of a conventional technique. 10 …… Printer body 18 …… Recording paper 22 …… Tray 24 …… Drive lever 26 …… Feed roller 27 …… Spring 28 …… Following plate 30 …… Link 32 …… Crank plate 34 …… Following member 36 …… Action part 38 …… Rotating shaft 40 …… Pin 42 …… Guide groove.

Claims (1)

[Scope of utility model registration request] 1. A paper feed mechanism of a printer that feeds recording paper one by one by friction with a feed roller, and is rotatable between a standby position separated from the feed roller and a position where the recording paper is pressed against the feed roller. A shaft-mounted drive lever, a coil spring whose one end is hooked on the drive lever and biases the drive lever in a direction to press the recording paper against the feed roller, and the other end of the coil spring is hooked and biased by the coil spring. The link lever is slidable substantially in parallel and includes a link lever formed with a groove that engages with a pin projecting from the drive lever, and the link lever is slid in a direction that weakens the biasing force of the coil spring. The end receives the pin and the drive lever is held in the standby position against the bias of the coil spring, and the link lever is attached to the coil spring. When the slider is slid in the direction of increasing the biasing force of the coil spring, the biasing force of the coil spring causes the drive lever to rotate in the direction in which the recording paper is pressed, and the biasing direction of the coil spring is determined by the rotation fulcrum of the drive lever and the action point of the coil spring. A paper feeding mechanism of a printer, which is configured to form an acute angle with a line connecting with.