JPH0360318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a friction feed mechanism for recording paper in a printer or the like.

[Conventional technology]

Conventional friction feed mechanisms have a structure in which a spring is fixed to the printer frame and the pinch roller is held by this spring, or a structure in which the pinch roller is pressed by a spring attached to the bottom plate of the printer. be.

[Problem that the invention seeks to solve]

In these conventional mechanisms, the rollers are held by springs, making them difficult to assemble.Also, the pinch rollers are in elastic contact with the platen with the same strong pressing force both when inserting and feeding the recording paper, so the recording paper is held between the two. It is difficult to insert the paper between the sheets, and it is difficult to set the paper.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a mechanism that can selectively change the force for pressing a pinch roller against a platen into two levels, strong and weak, and that is easy to assemble.

[Means for solving problems]

The present invention provides a platen 1 that is rotationally driven during paper feeding.
, a support shaft 2 located parallel to the platen and rotated in a fixed position, and a support arm 3 attached to the support shaft 2 and swinging within a predetermined angular range by rotation of the support shaft. , a roller receiver 4 having a pinch roller 5 in elastic contact with the platen at one end; a connecting means for rotatably and movably connecting the tip of the support arm 3 and the other end of the roller receiver 4; A biasing spring 6 is stretched between the support arm 3 and the roller receiver 4, and a biasing spring 6 is connected between the support arm 3 and the roller receiver 4 at a position slightly away from the line of action of the force of the biasing spring 6 toward the connecting means. It has a protrusion 3d protrudingly formed on one side of the roller receiver 4 and a protrusion receiver 4d recessed on the other side. The support arm 3 is connected to the roller receiver 4.
When the roller receiver 4 is in the retracted position, which is oscillated to the opposite side, the roller receiver 4 is moved between the protrusion 3d and the protrusion receiver 4.
When the support arm 3 receives a rotational moment from the biasing spring 6 using the engagement portion with the d as a fulcrum, and is in the forward position where the support arm 3 is oscillated in the direction of the roller receiver 4, the displacement of the support arm 3 As the roller receiver 4 is pushed forward in conjunction with the roller receiver 4, the roller receiver 4 receives a rotational moment from the biasing spring 6 using the connecting means as a fulcrum.

[Effect]

Therefore, the rotational moment of the support arm 3 in the retracted position is small because its fulcrum is close to the line of action of the force of the biasing spring 6, and the pinch roller 5 comes into elastic contact with the platen 1 with a weak pressing force. Also support arm 3
The rotational moment in the forward position of is large because its fulcrum is far from the line of action of the force of the biasing spring 6.
The pinch roller 5 comes into elastic contact with the platen 1 with a strong pressing force.

〔Example〕

In FIG. 1, recording paper P is fed in the direction of the arrow along the outer periphery of platen 1, which is rotationally driven during paper feeding. A support shaft 2 is provided parallel to the platen 1, the support shaft 2 has a hexagonal cross section, and is rotated within a predetermined range by a manual lever (not shown). A support arm 3 is attached to the support shaft 2. That is, the support arm 3 extends integrally from a boss portion 3a that fits into the support shaft 2, and the distal end portion 3b is integrally provided with a connecting shaft 3c. A protrusion 3d is provided in a part of the boss portion 3a. A spring hook 3e is integrally formed on the support arm 3, and this spring hook is provided at a position closer to the platen 1 by a small distance than the protrusion 3d. A roller receiver 4 is connected to the support arm 3. That is, a connecting groove 4a is provided at one end of the roller receiver 4, which engages with the connecting shaft 3c and is rotatable and movable. The other end of the roller receiver 4 is a roller bearing portion 4b, and a pinch roller 5, which is in elastic contact with the platen 1, is rotatably supported. Vertical bent pieces 4c, 4c are provided on both sides of the roller receiver 4, and protrusion receivers 4d, 4d recessed so as to engage with the protrusion 3d are formed. A spring hook 4e is provided on the roller receiver 4, and a biasing spring 6 is stretched between the spring hook 4e and the spring hook 3e of the support arm 3.

In conjunction with the rotation of the support shaft 2, the support arm 3 moves from a retracted position (solid line position in Figure 1), in which it is oscillated in the opposite direction to the roller receiver 4, to a forward position, in which it is oscillated in the direction of the roller receiver 4. It swings within an angular range up to the chain line position in Figure 1).

When the support arm 3 is in the retracted position, the protrusion receiver 4d of the roller receiver 4 engages with the protrusion 3d by the spring force of the biasing spring 6, and this engagement position is the fulcrum 0 ₁
(as shown in the third figure). This fulcrum 0 ₁ is located slightly away from the line of action of the force of the biasing spring 6, that is, the line connecting the spring hooks 3e to 4e, toward the connecting means consisting of the connecting shaft 3c and the connecting groove 4a. The distance from the fulcrum 0 ₁ to the line of action of the spring force is
When l ₀ and the spring force of the biasing spring 6 are F ₀ , the rotational moment due to the biasing spring at the fulcrum 0 ₁ is F ₀ ,
l ₀ . If the distance from fulcrum 0 ₁ to the point of contact between platen 1 and pinch roller 5 is l ₁ , and the reaction force of the pinch roller's elastic contact with the platen is F ₁ , then
The rotational moment due to the reaction force F ₁ at the fulcrum 0 ₁ is
F ₁ , l ₁ and are balanced with the above moment F ₀ l ₀ . Therefore, F ₁ =F ₀ ·l ₀ /l ₁ , and since l ₁ is extremely large compared to l ₀ , l ₀ /l ₁ has an extremely small value. Therefore, F ₁ is an extremely small force.
That is, when the support arm 3 is in the retracted position, the pinch roller 5 is in elastic contact with the platen 1 with a weak pressing force.

When the support arm 3 is in the forward position, the roller receiver 4 is pushed by the support arm 3 via its connection, so that the protrusion 3d and the protrusion receiver 4d
There is a separation between the two. Therefore, the connecting means between the connecting shaft 3c and the connecting groove 4a is held as a fulcrum 0 ₂ (shown in the fourth figure). The fulcrum 0 ₂ is further away from the line of action of the spring force than the fulcrum 0 ₁ . If the distance from the fulcrum 0 ₂ to the line of action of the spring force is l ₃ , the distance to the contact point between platen 1 and pinch roller 5 is l ₂ , and the reaction force on the pinch roller is F ₂ , then
The rotational moment F _{2 l 2} and F ₀ l ₃ due to the reaction force F ₂ and the spring force F ₀ at the fulcrum 0 2 are balanced. Therefore, F ₂ =F ₀ ·l ₃ /l ₂ . Since l ₃ /l ₂ is a sufficiently large force compared to l ₀ /l ₁ , F ₂ is an extremely large force compared to F ₁ . That is, in the forward position of the support arm 3, the pinch roller 5 is in elastic contact with the platen 1 with a strong pressing force.

Contrary to illustration, the protrusion 3d and the protrusion receiver 4d are
A protrusion may be provided on the roller receiver, and a protrusion receiver may be provided on the support lever. Further, the connecting shaft 3c and the connecting groove 4a may be formed oppositely in the same manner as described above.

Therefore, when inserting the recording paper P, insert it until it hits the pinch roller 5 at the retracted position of the support arm 3 (solid line in Figure 1), and then swing the support arm 3 to the forward position. is the first
The pinch roller 5 is pushed toward the upper right as shown by the chain line in the figure, and the pinch roller 5 firmly holds the front end of the recording paper P in its mouth and clamps it with a strong pressing force. When the platen 1 is rotated, the recording paper P moves forward along the platen 1 and passes in front of the platen.

Also, when using continuous paper as the recording paper for printing and feeding it with a pin tractor, etc., the support arm 3
is set in the retracted position, and the pinch roller 5 is brought into elastic contact with the platen 1 with a weak spring force. This applies appropriate tension to the recording paper, making it possible to print clearly.

During assembly, the support shaft 2 to which the support arm 3 is attached is attached to the frame of the printer.
Connect one end of the biasing spring 6 to the spring hook 4e of the roller receiver 4.
The process is completed by hooking the other end to the spring hook 3e of the support arm 3, and inserting the connection shaft 3c of the support arm 3 into the connection groove 4a of the roller receiver 4.

〔Effect of the invention〕

As described above, in the present invention, the force with which the pinch roller makes elastic contact with the platen is different depending on the forward position and the backward position of the support arm. This is extremely useful when inserting recording paper. It is also easy to assemble and has good workability.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of the main part, FIG. 2 is a plan view, and FIGS. 3 and 4 are schematic diagrams for explaining the operation. 1...Platen, 2...Support shaft, 3...Support arm,
3c...Connection shaft, 3d...Protrusion, 4...Roller receiver, 4
a...Connection groove, 4d...Protrusion receiver, 5...Pinch roller, 6...Biasing spring.

Claims (1)

[Scope of Claims] 1. A platen that is rotationally driven when paper is fed, a support shaft that is located parallel to the platen and rotates in a fixed position, and a support shaft that is attached to the support shaft and that swings as the support shaft rotates. a displacing support arm, a roller receiver having a pinch roller at one end that comes into elastic contact with the platen, and a connecting means for rotatably and movably connecting a tip end of the support arm and the other end of the roller receiver; An urging spring tensioned between the support arm and the roller receiver, and one of the support arm and the roller receiver at a position slightly away from the line of action of the urging spring force toward the connecting means. a protrusion protrudingly formed on one side and a protrusion receiver provided on the other side, and when the support arm is in a retracted position in which the supporting arm is swung to the opposite side to the roller receiver, the roller receiver is connected to the protrusion. It receives a rotational moment from the biasing spring with the engagement portion with the protrusion receiver as a fulcrum, and when the support arm is in the forward position where it is oscillated in the direction of the roller receiver, it is linked to the displacement of the support arm. A friction feed mechanism for recording paper, characterized in that when the roller receiver is pushed forward, the roller receiver receives a rotational moment from the urging spring about the connecting means as a fulcrum.