JPH03230977A - Microprinter - Google Patents

Abstract

PURPOSE:To easily unlock a paper feed gear by arranging a spring clutch mechanism between the paper feed gear and a paper feed shaft. CONSTITUTION:A spring clutch 16 for transmitting the rotary power from a drive motor is connected to the input gear of an electromagnetic clutch 8 and has a drive gear 17. When a user pulls paper to lock the timing gear 2 of a paper feed gear 1 and an LF clutch gear 5 at the time of paper feed, the coil spring 29 of the paper gear 1 is loosened and the paper feed gear 1 becomes possible to race with respect to a paper feed shaft 3. Since the loose torque of the coil spring 22 of the drive gear 17 is set so as to be larger than that of the coil spring 29 of the paper feed gear 1, a main gear 6 is rotated by the loose torque of the coil spring 22 of the spring clutch 16 of the drive gear 17 to make it possible to rotate the LF clutch gear 5. By this constitution, the paper feed gear 1 is rotated to a predetermined position to make it possible to unlock the paper feed gear 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microprinter, and particularly to a microprinter that performs printing using a type holder having a plurality of type characters formed on its outer periphery.

[Conventional technology]

Conventionally, a type holder with type arranged on its outer peripheral surface is rotatably provided, and the type holder is stopped at a desired type position based on a predetermined type signal, and in this state, printing is performed using a hammer or the like. 2. Description of the Related Art Microprinters that use a mechanism to print desired characters on paper are often used.

FIG. 5 shows a paper feeding mechanism applied to this conventional microprinter, in which a timing gear 2 is formed on one side of a paper feeding gear 1 that is driven only during paper feeding operation. . A paper feed shaft 3 is coaxially fixed to the other side of the paper feed gear 1, and the paper feed shaft 3 has the following features:
A paper feed roller 4 that is pressed against paper (not shown) is attached.

Further, as shown in FIG. 6, the timing gear 2 of the paper feed gear 1 is engaged with an LF clutch gear 5 which is intermittently engaged with an intermittent gear coaxially attached to a type holder (not shown). During type selection and printing, this LF clutch gear 5 holds the paper feed gear 1 in a state in which it is not engaged with the intermittent gear and exerts a predetermined paper feed holding force, and when non-printing, the LF clutch gear 5 It is rotated in accordance with the rotation of the feed gear 1 and meshed with the teeth of the intermittent gear.

In such a paper feeding mechanism, driving force from a drive motor (not shown) is transmitted to the paper feeding gear 1 during non-printing,
In response to this, the paper feed gear 1 is driven to rotate, and a predetermined paper feed is performed.

[Problem to be solved by the invention]

However, in the paper feeding mechanism of the conventional microprinter, as shown in FIG. There is a problem in that the paper feed gear 1 is rotated more or less than a predetermined feed amount, and the timing gear 2 of the paper feed gear 1 and the gear of the LF clutch gear 5 are locked.

In addition, when such a lock occurs, since the driving force to the paper feeding gear has already not been transmitted, the lock can be removed by rotating the LF clutch gear 5 via the intermittent gear of the type drum. It is necessary to release the state, but for example, when a spring clutch is used as the rotation transmission mechanism to the type drum, the torque required to rotate the LF clutch gear 5 is equal to the loosening torque of the spring clutch. Since the rotational force is larger than that transmitted by the LF clutch gear 5, the LF clutch gear 5 cannot be rotated and the lock cannot be released.

The present invention has been made in view of these points, and it is an object of the present invention to provide a microprinter whose paper feed gear can be easily unlocked.

[Means to solve the problem]

In order to achieve the above object, the microprinter according to the present invention is provided with a type holder having type characters formed on its outer peripheral surface, rotatable by a drive motor via a drive transmission mechanism, and rotatably driven by the drive motor when not printing. In the micro printer, a paper feed gear is provided, and a paper feed shaft to which a paper feed roller that is pressed against the paper is attached is fixed to the paper feed gear. The feature is that a spring clutch mechanism is disposed in between.

[For production]

According to the present invention, when a user pulls the paper during paper feeding and the paper feeding gear is locked, the spring clutch mechanism of the paper feeding gear allows the paper feeding gear to idle relative to the paper feeding shaft. , the paper feed gear can be easily unlocked. Furthermore, with the spring clutch mechanism, when paper feeding is stopped, if the paper is pulled in the forward direction, a tightening torque is generated and a high paper holding force can be obtained, and if the paper is pulled in the opposite direction, the loosening torque is generated. This can prevent damage to the gear due to abnormal force being applied to the paper feed gear portion, which would result in the paper feed roller idling.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows an embodiment of the present invention, which includes a type holder (not shown) in which two sets of type characters to be printed in different colors on the outer peripheral surface are arranged and divided into half circumferences. At one end,
A main gear 6 and an intermittent gear 7 are attached, and ratchet teeth corresponding to the printed characters and two notched grooves corresponding to the portions where the printed characters are not formed and formed deeper than the grooves between the ratchet teeth are respectively provided. A formed ratchet (not shown) is coaxially mounted.

Further, an electromagnetic clutch 8 is disposed near the main gear 6, and the electromagnetic clutch 8 has an input gear (not shown) that meshes with the main gear 6. A yoke 9 that is rotationally driven integrally with the input gear is attached to the tip of the rotating shaft of the input gear, and an electromagnetic coil 10 is housed inside the yoke 9.

Furthermore, electromagnetic plates 1 to 1 are provided on the end surface side of the yoke 9.
1 are arranged coaxially, and this electromagnetic play 1-11
When the electromagnetic coil 10 is energized, it is attracted to the yoke 9 and rotated together with the yoke 9 in the counterclockwise direction 61 in FIG.

Further, each of the electromagnetic plays 1 to 11 has an engaging claw 1 at the tip.
A selection lever 13 is connected thereto, and is rotatable about a support shaft 13a located approximately at the center.A rod-shaped locking portion 14 is formed to protrude from the selection lever 13. Further, a lever spring 15 is connected to the selection lever 13, and is configured to bias the selection lever 13 in the opposite direction. Then, the selection lever 13 is moved by the lever spring 1 by the rotation of the electromagnetic plate 11.
The engagement pawl 12 selectively engages the tooth with the radiator 1 of the radiator 1, or rotates to the bottom of the notched groove, and can be disengaged. .

Further, in this embodiment, a spring clutch 16 as shown in FIG. 2 that transmits rotational force from a drive motor (not shown) is connected to the input gear of the electromagnetic clutch 8. , drive gear 1
7. A drive shaft 18 is integrally fixed to this drive gear 17, and on the outer circumferential side of this drive shaft 18,
The engagement cylinder 20 of the clutch gear 19 is loosely fitted. This engagement tube 20 has a locking groove 2 extending in the axial direction.
1 is formed on the outer circumferential side of the drive shaft 18 and on the inner circumferential side of the engagement cylinder 20, and a spring 22 is configured so that its hook portion 22a engages with the locking groove 21. A drive motor (not shown) is connected to the drive gear 17, and the input gear of the electromagnetic clutch 8 is engaged with the clutch gear 19. When a certain torque is applied to the clutch gear 19, the coil spring 22 slips on the drive shaft 18 and no longer transmits rotational force to the manual gear.

Further, a control gear 23 is disposed near the spring clutch 16 and is partially engaged with the drive gear 17 thereof, and a locking portion of the selection lever 13 is provided on one side of the control gear 23. 14 is formed. A control spring 25 is attached to the engagement 1F projection 24.
When the locking portion 14 and the locking protrusion 24 are unlocked by rotating the selection lever 13, the biasing force of the control spring 25 causes the The control gear 23 is rotated in the counter-clockwise direction.
3 is engaged with the drive gear 17 of the spring clutch 16.
It is designed so that

Further, a paper feed gear 1 is meshed with the control gear 23, and a timing gear 2 is formed on one side of the paper feed gear 1. The paper feed gear 1 includes a third
As shown in the figure, a paper feed shaft 3 is connected via a spring clutch mechanism 26, and a paper feed roller 4 (not shown) that is pressed into contact with a sheet of paper is fixed to this paper feed shaft 3. The spring clutch mechanism 26 includes an engagement tube 27 formed on the other side of the paper feed gear 1 and a drive shaft 28 that is integrally fixed to the end of the paper feed shaft 3. A coil spring 29 is attached between the shaft 28 and the engagement tube 27 so that its hook portion 29a engages with a locking groove 30 formed in the engagement tube 27. , and when torque is applied to the paper feed roller 4, such as when the paper is pulled, the coil spring 2
9 is a slip l), so that rotational force is no longer transmitted to the paper feed gear 1.

Further, a 1-F clutch gear 5 is disposed between the paper feed gear 1 and the intermittent gear 7, and is engaged with the timing gear 2 of the paper feed gear 1 and the intermittent gear 7, respectively. During character selection and printing, this LF clutch gear 5 holds the paper feed gear 1 without engaging the intermittent gear 7 to produce a predetermined paper feed holding force, and when not printing, It is rotated in accordance with the rotation of the paper feed gear 1 and meshed with the teeth of the intermittent gear 7.

Next, the operation of this embodiment will be explained.

First, in the initial position, the engaging claw 1 of the selection lever 13 is
2 is not engaged with the ratchet, and in this state, the drive motor rotates the drive gear 17 of the spring clutch 16 to transmit the rotation of the drive shaft 18 to the engagement tube 20 via the coil spring 22. The clutch gear 19 is rotated to rotate the type drum via the input gear of the electromagnetic clutch 8 and the main gear 6, and the yoke 9 of the electromagnetic clutch 8 is also rotated.

During this half-rotation, the electromagnetic coil 10 of the electromagnetic clutch 8 is energized at a desired print position based on a signal corresponding to the print character, so that the electromagnetic plate 11 is attracted to the yoke 9. As a result, the selection lever 13 is rotated clockwise about the support shaft 13a, causing the engagement pawl 12 of the selection lever 13 to engage with the ratchet teeth of the ratchet, and moving the type drum to a predetermined position. Stop at the type position.

At this time, the locking portion 14 of the selection lever 13 is connected to the control gear 23.
It is held in a state in which it is in contact with the locking protrusion 24 of 1. When the type holder stops, a load is applied to the clutch gear 19 of the spring clutch 16, so that slippage occurs between the inner circumferential surface of the coil spring 22 and the outer circumferential surface of the drive shaft 18. This occurs, causing the drive gear 17 to idle, and no rotational driving force is transmitted to the clutch gear 19. In this state, desired printing is performed on the paper by a printing mechanism such as a hammer (not shown), and in this way, while the type holder makes half a rotation, one
The line is printed.

When printing is completed, the electromagnetic clutch 8 is de-energized, and the selection lever 13 is rotated in the opposite direction J1 by the lever spring 15 to engage the engagement claw of the selection lever 13. 12 and the ratchet teeth of the radiators 1 to 1 are released, thereby releasing the load on the spring clutch 16 and causing the type holder to rotate again via the main gear 6.

When paper is to be fed, the electromagnetic clutch 8 is energized to rotate the electromagnetic plate 11, and the engaging pawl 12 of the selection lever 13 is rotated to the bottom of the notch groove of the ratchet. 13 rotates more clockwise than when selecting a type, and the locking portion 14 of the selection lever 13 engages with the locking protrusion 24 of the control gear 23.
The control gear 23 is removed by the force of the control spring 25.
is rotated counterclockwise, and this control gear 23 and drive! II
'The gear 17 is meshed with the gear 17. As a result, the control gear 23
is rotated, the paper feed gear 1 is rotated, and the paper feed roller 4 is rotated.
The paper is conveyed by a predetermined amount by the rotation of . At this time, the fourth
As shown in FIGS. (a) to (e), when the gear of this LP clutch gear 5 meshes with the teeth of the intermittent gear 7, the LF clutch gear 5 is also rotated, and the 1F clutch gear 5 is rotated. will not be hindered.

By repeating the above operations, the required number of lines is printed.

Furthermore, when the user pulls the paper during paper feeding and the timing gear 2 of the paper feeding gear 1 and the LF clutch gear 5 are locked, the coil spring 29 of the paper feeding gear 1 becomes loose.
This paper feed gear 1 can now idle relative to the paper feed shaft 3, and in this embodiment, the loosening torque of the coil spring 22 of the drive gear 17 is smaller than the loosening torque of the coil spring 29 of the paper feed gear 1. Since the coil spring 2 of the spring clutch 16 of the drive gear 17 is formed large,
2, the main gear 6 can be rotated to rotate the LF clutch gear 5, and thereby the paper feed gear 1 can be rotated to a predetermined position and unlocked. It is something.

Furthermore, since the spring clutch mechanism 26 is interposed between the paper feed roller 4 and the paper feed gear 1, when the paper is pulled in the forward direction when the paper feed is stopped, the coil spring 29 is tightened and torque is applied. As a result, the fill spring 29 wraps around the drive shaft 28 and can obtain a high paper holding force.
Also, if the paper is pulled in the opposite direction, the coil spring 29
Since the paper feed roller 4 becomes loose and the paper feed roller 4 rotates idly, it is possible to prevent damage to the gear due to abnormal force being applied to the paper feed gear 1 portion.

Therefore, in this embodiment, when the timing gears 2 and 1-1 of the paper feed gear 1 are turned off by pulling the paper, the paper feed gear 1 can be easily rotated. Roughly speaking, when the paper is stretched in the forward direction by the spring clutch mechanism 26 when the paper feed is stopped, the spring 29 is tightened to obtain a high paper holding force. If the paper is pulled in the opposite direction, the spring 29 will become loose and the paper feed roller 4 will idle, and an abnormal force will be applied to the paper feed gear 1. 1 can be prevented from being damaged.

4T Please note that the present invention is not limited to the above-mentioned embodiments (it is possible to make various changes as necessary).

〔Effect of the invention〕

As described above, the microprinter according to the present invention has a spring-clap mechanism disposed between the paper feed 1a and the paper feed shaft, so that the user can easily release the lock of the 5a by pulling the paper. can do. Furthermore, due to the spring clutch TA structure, when the paper is pulled in the forward direction when the paper feed is stopped, a tightening force of 1 to 1 torque is generated and a high paper holding force can be obtained, and when the paper is pulled in the reverse direction, , one herk of loosening occurs, causing the paper feed roller to idle, and damage to the gear due to abnormal force being applied to the paper feed gear portion can be prevented.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the drive mechanism of a microprinter according to the present invention, Fig. 2 is an exploded perspective view showing a spring clutch of the drive gear, and Fig. 3 is an exploded perspective view showing the spring clutch mechanism of the paper feed gear. Exploded perspective view shown in Fig. 4(a), (
b), (c). (d) and (e) are explanatory diagrams showing the engagement states of the paper feed gear and the LF clutch gear, respectively. Fig. 5 is a perspective view of the conventional paper feed gear portion, and Fig. 6 is the conventional paper feed gear and the LF clutch gear. FIG. 6 is an explanatory diagram showing a locked state with the clap gear. ]... Paper feed gear, 2... Timing gear, 3...
・Paper feed shaft, 4...Paper feed roller, 5...What-1-clutch gear j7.6...Main gear, 7...Intermittent gear, 8...Electromagnetic notch, 13... Selection lever 1
6... Spring clutch, 17... Drive gear, 1
9... Clap gear, 22.29... Coil spring,
23...Control gear, 26...Spring clutch mechanism.

Claims (1)

[Claims] A type holder having type formed on its outer peripheral surface is rotatably provided by a drive motor via a drive transmission mechanism, and a paper feed gear is provided which is rotationally driven by the drive motor when not printing, and the paper feed gear A microprinter comprising a paper feed shaft fixedly attached with a paper feed roller that presses against the paper, characterized in that a spring clutch mechanism is disposed between the paper feed gear and the paper feed shaft. micro printer.