JPH03182445A - Sheet transfer mechanism - Google Patents

Abstract

PURPOSE:To transfer a sheet with the proper pressing force corresponding to the thickness of the sheet and prevent a wrinkle on a thin sheet and a slip of a thick sheet by providing an exciting means pressing a push lever in the shift direction of a roller and a cam-type roller pressing the push lever in the opposite direction to the exciting means. CONSTITUTION:The pressing force of a roller 15 to a sheet is changed by the balance between forces applied to a push lever 11 by an exciting means 2 and a cam-type roller 13. The cam-type roller 13 is rotated according to the thickness of the sheet, and the pressing force to the sheet can be adjusted in many steps by the number of rollers put into contact with the sheet. A motor is connected to the cam-type roller 13, a signal corresponding to the thickness of the sheet is applied, thereby the pressing force adjustment can be easily automated.

Description

[Detailed description of the invention]

[Summary] The present invention relates to a paper conveyance mechanism for cut sheets, and the purpose of the present invention is to provide a paper conveyance mechanism that applies an appropriate pressing force to a conveyance roller in accordance with various types of paper. In a paper conveyance mechanism in which paper is conveyed by being caught between conveyance rollers, at least one of a pair of paper conveyance rollers that engage the paper is movable toward the other roller, and a push lever that supports the plurality of rollers is provided. , a biasing means for pushing the push lever in the moving direction of the roller, and a cam type roller for pushing the push lever in a direction opposite to the biasing means. [Industrial Field of Application] The present invention relates to a paper conveyance mechanism for cut sheets. In recent years, with the spread of printing devices for personal users such as word processors, the thickness of paper used by users has diversified, and a paper transport mechanism that can accommodate this has become necessary. In a paper transport mechanism that accommodates various paper thicknesses, when the paper is thin like Japanese paper, wrinkles may occur if the pressing force of the transport roller of the paper transport mechanism is too strong. On the other hand, when using thick paper, if the pressing force of the conveyance roller of the paper conveyance mechanism is too weak, the paper may slip and cannot be conveyed properly. For this reason, it is important to adjust the pressing force of the conveying roller against the paper to an appropriate pressing force corresponding to the paper to be conveyed. [Prior Art] FIG. 8 is a side view showing a conventional paper conveyance mechanism. In the figure, the paper passes between a paper tray 81 and a paper holding table 82, and is conveyed by being caught by paper conveyance rollers 83 and 84. The paper pressing force is fixed by the force of the spring 85 pushing up the pressing roller 84, and the paper pressing force is fixed at the time of factory assembly according to various paper specifications. [Problem to be solved] As a result, the range of paper thickness to be transported becomes narrower, and a paper transport mechanism set for thick paper will cause wrinkles on thin paper that is out of specification. The conveyance mechanism had a problem in that it caused a slip phenomenon when using thick paper that did not meet the specifications. SUMMARY OF THE INVENTION An object of the present invention is to provide a paper conveyance mechanism that applies appropriate pressing force to a conveyance roller according to various types of paper. [Means for Solving the Problems] The IT diagram is a diagram explaining the principle of the present invention. In the figure, 11 is a push lever that supports a plurality of movable rollers. Reference numeral 12 denotes a biasing means, which applies a force to push the push lever 11 in a direction in which the roller can move. 1
A cam type roller 3 is in contact with the push lever 11 and applies a force to push the push lever 11 in the opposite direction to the urging means 12. [Function] With the above configuration, the biasing means 12 and the cam type roller 1
The pressing force of the rollers against the paper changes depending on the balance of the forces applied to the push levers 11 of 3. Therefore, in the present invention, by rotating the cam type roller according to the thickness of the paper, the pressing force against the paper can be adjusted in multiple stages by changing the number of rollers that come into contact with the paper. Further, with such a configuration, the pressing force adjustment can be easily automated by connecting a motor to the cam type roller and providing a signal according to the paper thickness. 〔Example〕

First Embodiment FIG. 2 is a first embodiment of the present invention, and shows a perspective view of a paper conveyance mechanism. In the figure, 21 is a paper presence/absence detection sensor that recognizes the presence or absence of paper. The paper presence/absence detection sensor 21 includes, for example, a light transmission type detection sensor or a light reflection type detection sensor. A paper thickness detector 22 detects the thickness of the paper being conveyed by measuring the distance to the paper. An example of such a paper thickness detector is one that uses a mechanism similar to a key on a keyboard switch and is configured to detect the depressing stroke until the tip of the key touches the paper by the number of driving pulses of a depressing pulse motor. can be used. Reference numeral 23 denotes a motor, which rotates under the control of a paper thickness signal from the paper thickness detector 22. 24 is a cam type roller, and in the figure, there are four cams 24-
1 to 24-4 are installed out of phase. Reference numerals 25-1 to 25-4 are push levers, and springs SPI to SP4, which serve as biasing means, are installed in the center of each push lever.
is attached. The springs SPI to SP4 have spring constants of 2, respectively. The pressing force of the cams 24-1 to 24-4 of the cam type roller 24 and the springs SP1 to SP4 change the vertical positions of the push levers 25-1 to 25-4. 26 is a pressure roller, and the push lever 25-1
The pressing force against the paper can be changed by vertical movement of 25-4. Reference numeral 27 denotes a paper feed roller, which works as a pair with the pressure roller 26 to transport the paper by biting the paper.Next, the paper transport mechanism will be explained. First, with paper/
When the non-detection sensor 21 detects the presence of paper, the paper presence/absence detection sensor 21 issues a signal to operate the paper thickness detector 22. The paper thickness detector 22 that receives this activation signal recognizes the paper thickness of the paper currently being fed. Based on the recognition result of the paper thickness detector 22, the motor 23 is turned to rotate the cam type roller 24, and the push levers 25-1 to 25-4, which are supported by springs SPI to SP4 having different spring forces, are moved up and down. By letting
It controls the pressing force on the paper at the bottom of the paper feed roller 26. FIG. 3 is a configuration diagram of an embodiment of a cam type roller. FIG. 3A is a perspective view of the cam-type roller, and FIG. 1B is a side view of the cam-type roller, showing cams 24-1 to 24-4 from the left. The cam type roller has protrusions every 120'' as shown in FIG. 3(a), and each cam 24-1
~24-4 are attached with the adjacent parts out of phase with each other. Further, the cams 24-1 to 24-4 are in contact with the push levers 25-l to 25-4, respectively. FIG. 4 is an explanatory diagram of the relationship between the cam type roller and the pressing roller. FIG. 5(a) is a diagram in which the protruding portion of the cam-type roller is in contact with the push lever, and FIG. 3(b) is a diagram in which the portion of the cam-type roller that is not the protruding portion is in contact with the push lever. As shown in FIG. 4(a), the protruding portion of the cam contacts the push lever 25 and pushes the push lever 25 down, so that the pressure roller 26 does not rest on the push lever 25. On the other hand, as shown in FIG. 4(b), when the non-protruding portion of the cam comes into contact with the push lever 25, the spring SP lifts the pressing roller 26 with a pressing force P corresponding to the spring constant k. Hereinafter, we will look at the pressing force applied to the pressing roller by dividing the cam type roller into rotation periods (■-■) as shown in FIG. 3(b). When the cam synchronization timing ■ is at the bottom, the cam 24-2 and the cam 2 rotate as shown in Fig. 5(a).
The protrusion 4-4 pushes down the push lever 25-2 and the push lever 25-4. For this reason, the pressure roller 26
It is not the push levers 25-2 and 25-4 that hold L, but the push levers 25-1 and 25-3, which are lifted by the spring constant. Therefore, a constant pressing force P1 given by the spring constant is applied to the pressing roller 26. With this constant pressing force PI, the pressing roller 26 presses and conveys the paper. Also, when the cam rotation timing ■ is at the bottom, the 5th e (
As shown in b), the protrusions of the cams 24-1 and 24-3 are connected to the push levers 25-1 and 25-3.
Press down. Therefore, the push levers 25-1 and 25-3 lift the pressure roller 26.
Rather, the push levers 25-2 and 25-4 are lifted by the spring constant. Therefore, a constant pressing force P given by the spring constant kt is applied to the pressing roller 26. With this constant pressing force P2, the pressing roller 26 presses and conveys the paper. On the other hand, when the cam rotation timing ■ is at the bottom, as shown in Figure 5 (c
), the non-protruding portions of the cams 24-1 to 24-4 uniformly contact the bushing levers 25-1 to 25-3. Therefore, lifting the pressure roller 26 requires
Push levers 25-1 and 25-3 are lifted by springs with a spring constant of 1, and push lever 2 is lifted by a spring with a spring constant of 2.
5-2 and push lever 25-4. Therefore, a constant pressing force P, +p given by +kt is applied to the pressing roller 26 in addition to the spring constant. The pressing roller 26 presses and conveys the paper with the constant pressing forces P and +p. That is, at the rotation timing of the cam type roller 24, the pressure roller 2
6 presses the paper with a pressing force of P, at rotation period ■ the press roller 26 presses the paper with a pressing force of P2, and at rotation period ■ the press roller 26 presses the paper with a pressing force of P1 + Pt. As explained, the cam type roller shown in FIG. 3 has three types of pressing force, and the pressing force can be selected depending on the paper. Further, by increasing the number of cams attached to the cam type roller 24 rather than just four, and by increasing the types of spring constants of the springs attached to the bushing lever 25, the width of the pressing force for pushing the paper can be increased.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention, and shows a perspective view of a paper conveyance mechanism. In the figure, the same parts as in FIG. 2 are given the same reference numerals. Different from FIG. 2, the pressure rollers of the sheet pressure adjustment means are independent for each pressure roller, which has two rollers. FIG. 7 shows an enlarged perspective view of the pressure roller. The roller portions of this pressure roller are made of pressure rollers 61-l to 61-4 having different hardnesses. For example, the pressure roller 61-1.6i-3 is made of hard rubber,
Pressing rollers 61-2 and 61-4 are formed using soft rubber. Then, depending on the rotation angle of the cam, the paper is fed by the pressure rollers 612 and 61-4 made of soft rubber when the paper is thin, and the pressure rollers 61-1 and 61-3 made of hard rubber are used when the paper is thick. Make sure to feed the paper. As described above, the pressure rollers 61-1 to 6I with two different hardnesses are used.
4 was considered, but by attaching a plurality of rollers having a plurality of types of different hardnesses, it becomes possible to select a pressure roller having an appropriate pressing force depending on the stage of paper thickness. Then, the paper is conveyed by the selected pressure roller. In addition, in the above embodiment, if the pressure roller is made of a roller made of different materials (for example, made of rubber or plastic), even if the paper being conveyed is paper that has not yet been printed, the printing will not be possible. For example, in the figure, among the four pressure rollers 61-1 to 614, pressure rollers 61-2 and 61-3 are assumed to be in contact with the printed portion. , the pressure roller 61-1, 61-4 shall be in contact with the non-printed area.At this time, the printing ink will not be lost to the pressure roller 61-2, 61-3 that is in contact with the printed area. The pressure roller is made of plastic, and the pressure roller 6 contacts the non-printed area.
1-1.61-4 is a rubber pressure roller that can reliably convey the paper. Therefore, each pressure roller 6
The pressing force of 1-1 to 61-4 is applied to the cam type rollers 24-1 to 24-2.
4-4 and springs spi to SP4, it is possible to select an appropriate pressing force for each portion of the paper to be conveyed (printed portion and non-printed portion). [Effects of the Invention] As explained above, according to the present invention, paper can be conveyed with an appropriate pressing force depending on the thickness of the paper. Furthermore, it is also possible to change the pressing force for each portion of the paper. Therefore, it is possible to prevent wrinkles in thin paper and slippage in thick paper, and furthermore, it is possible to prevent the printed portion from being damaged by the roller.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a first embodiment of the present invention, and is a perspective view of a paper conveyance mechanism, Fig. 3 is a configuration diagram of an embodiment of a cam type roller, (a) Perspective view of the cam type roller (b) Side view of the cam type roller Figure 4 is an explanatory diagram of the relationship between the cam type roller and the pressure roller. When the part of the mold roller that is not a protrusion comes into contact with the push lever Figure 5 is a perspective view of the cam type roller and the pressure roller, (a) When the rotation period is ■ (b) When the rotation period is ■ (c) When the rotation period is 6 shows a second embodiment of the present invention, and is a perspective view of a feeding mechanism, FIG. 7 is an enlarged perspective view of a pressure roller, and FIG. 8 is a side view of a conventional paper conveyance mechanism. In the paper transport diagram, 11: push lever 12: biasing means 13: cam type roller 14. 15: paper transport roller. Fig. 5 Pressing the rollers and pushing the rollers 5th Fig. 25

Claims (1)

[Claims] Paper of various thicknesses is transported by a pair of paper transport rollers (14, 15).
) A paper transport mechanism that transports the paper by biting the paper between the pair of paper transport rollers (14, 15), at least one of which is movable toward the other roller, and the plurality of rollers a push lever (11) that supports the push lever (11); a biasing means (12) that pushes the push lever (11) in the direction of movement of the roller;
) A paper conveyance mechanism characterized by comprising a cam-type roller (13) that pushes the paper.