JPS623543Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a spring clutch mechanism used to control the transmission of intermittent rotational motion, such as a bracket selection mechanism, a hammer drive mechanism, etc. in a printer.

A conventional spring clutch mechanism will be explained with reference to FIG. 1, taking as an example a mechanism used in a hammer drive mechanism in a printer.

In the figure, reference numeral M denotes a motor, 1 a first gear fixed to the output shaft of the motor M, 2 a second gear always meshed with the first gear 1, and the second gear 2.
A cylindrical drive arbor 3 is integrally formed with the cylindrical drive arbor 3.
The integrally formed driving arbor 3 and second gear 2 are rotatably mounted on the driven rotating shaft 4,
A coil spring S is tightly wound around the drive arbor 3.

Reference numeral 5 designates a hammer drive cam, and reference numeral 6 designates a ratchet provided with a notched locking portion 6a. Both the hammer drive cam 5 and the ratchet 6 are fixed to the driven rotating shaft 4, and the ratchet 6 is connected to the ratchet 6 via a stopper 7. One end of the coil spring S is locked. Reference numeral 8 denotes a control lever, and this control lever 8 is always provided with a tendency to slide into contact with the ratchet 6 by a spring (not shown), and is controlled to be locked and released from the notch locking portion 6a by an electromagnet (also not shown).

When the control lever 8 is not engaged with the notch engagement portion 6a of the ratchet 6, the driving force of the constantly rotating motor M is in a state where rotation can be transmitted to the driven rotating shaft 4 (hereinafter referred to as the on state). The rotation is transmitted to the hammer drive cam 5. The hammer drive cam 5 rotates and drives the hammer 11 to drive the type wheel 1.
2, the control lever 8 is locked in the notch locking portion 6a in the ratchet 6, as shown in FIG. 2A. In this locked state, the coil spring S is relaxed and the motor M
The driving force is in a state in which rotation cannot be transmitted to the driven rotating shaft 4 (hereinafter referred to as an OFF state), and during this time, the hammer 11 is returned to its original state by a spring force via an appropriate mechanism, and the rotation of the type wheel 12 is selected. Ru. Although not shown, the type selection operation is performed by controlling other clutches by utilizing the operation in which the control lever 8 fits into and locks the notch locking portion 6a (see FIG. 2A).
When the hammer drive cam 5 is not operating, the type wheel 12 rotates.

As mentioned above, when the required operation such as type selection operation is completed, the electromagnet is energized at the timing of this completion, and the control lever 8 is disengaged from the notch locking portion 6a (see Fig. 2B), and the spring clutch mechanism is activated. The hammer drive cam 5 returns to the on state and the hammer 11
rotate towards.

By the way, this type of printers are becoming smaller and more recently, they are often used as printing devices for calculators and the like, and batteries are often used as the power source for these printers. Therefore, in order to save power, the electromagnet is generally deenergized immediately after the control lever 8 is disengaged from the notch locking portion 6a. FIG. 2C shows this state, in which the driven rotating shaft 4 is rotating with the control lever 8 in frictional contact with the peripheral surface of the ratchet 6 due to the elasticity of the spring.

However, in such a conventional spring clutch mechanism, when the driven rotating shaft 4 rotates, the control lever 8 is in frictional contact with the circumferential surface of the ratchet 6 due to the elasticity of the spring. However, this frictional force acts to prevent the rotation of the ratchet 6 and turn the spring clutch mechanism into an OFF state, resulting in a problem that malfunction is likely to occur.

FIGS. 3A and 3B show another conventional example designed to deal with such problems. In this conventional example, stopper members 9 are disposed at appropriate locations, and the driven rotating shaft 4 is During rotation, the control lever 8 is held at a suitable distance d from the ratchet 6 by this stop member 9 (see FIG. 3B).

However, in such other conventional spring clutch mechanisms, the control lever 8 is connected to the locking pawl 6b on the ratchet 6, as shown in FIG. 3A.
Even when the control lever 8 is in the locked state, the movement of the control lever 8 is regulated by the stopper member 9, and as shown in FIG. Since the difference between the two clutches disappears, there is a practical problem in that the rotational position displacement of the control lever 8 at the time of locking cannot be used for other clutch control purposes.

This idea was created by focusing on the various problems of the conventional technology, and consists of a rotationally driven cylindrical arbor that is rotatably fitted around the outer periphery of the driven rotating shaft, and a locking part on the outer periphery. A provided ratchet is rotatably fitted around the outer periphery of the arbor, a circular driven disk having a notch on the outer periphery is fixed to the driven rotating shaft in close proximity to the ratchet, and is wound around the outer periphery of the arbor. One end of the coil spring is locked to the arbor, the other end of the coil spring is locked to the driven disk at a position where the notch and the locking part correspond, and controls are provided integrally with each other. The free end portions of the lever and the sub-lever are biased toward the outer circumferential surface of the ratchet and the driven disk, so that the free end portion of the sub-lever is slidably engaged with the outer circumferential surface of the driven disk, and the sub-lever is engaged with the outer peripheral surface of the driven disk, the free end of the control lever is separated from the outer peripheral surface of the ratchet and the locking portion, and the free end of the sub-lever is engaged with the notch. It is an object of the present invention to solve the above-mentioned problems by forming the control lever so that the free end of the control lever engages with the locking part when the control lever is in use.

This invention will be explained below based on the embodiments shown in FIGS. 4 and 5, in which this invention is applied to a clutch mechanism for driving a hammer in a printer.

In each of the figures from FIG. 4 onwards, the same or equivalent members or parts as in FIGS. 1 to 3 are designated by the same reference numerals and redundant explanations will be omitted.

First, the structure will be explained. In this invention, a hole 6c is bored in the center of the ratchet 6, and the ratchet 6 is rotatably attached to the drive arbor 3 through the hole 6c. Further, a driven disk 10 is fixed to a portion of the driven rotating shaft 4 near the end of the drive arbor 3. The driven disk 10 is
Its diameter is larger than the diameter of the ratchet 6 (the diameter of the portion other than the portion where the locking pawl 6b is provided), and a notch 10a corresponding to the locking pawl 6b in the ratchet 6 is provided on the peripheral surface. ing.

Both ends of a coil spring S are attached to the driven disk 10 and the ratchet 6, respectively, and the coil spring S is tightly wound around the drive arbor 3.

That is, one end of the coil spring S is locked to a stopper 7a fixed to the driven disk 10, and the other end is attached to the ratchet 6 via another stopper 7b. Stopper 7 on the ratchet 6 side
b is an arcuate long hole 6 bored in this ratchet 6.
d so that it can move slightly in the circumferential direction. Since the ends of the coil springs S are installed with a slight play in the circumferential direction in this manner, even if there are manufacturing variations in the coil springs S, assembly is facilitated.

Further, a linking plate 14 extends from the ratchet 6 toward the driven disk 10, and the end of the linking plate 11 can be moved a required amount in the circumferential direction into an arcuate long hole 10b bored in the driven disk 10. It is loosely fitted. Incidentally, this required amount of movement refers to the amount of rotation required to tighten (convert to the on state) or relax (convert to the off state) the coil spring S.

Further, a sub-lever 8a corresponding to the driven disk 10 is attached to the control lever 8.
The sub-lever 8a has substantially the same shape as the control lever 8, and both levers 8, 8a are integrally formed via a connecting portion 8b.

Next, the operation will be explained with reference to FIGS. 6A, B, and C.

The control lever 8 is now engaged with the locking pawl 6b of the ratchet 6.
When in the unlocked state, the spring clutch mechanism is in the on state, and rotation is transmitted to the hammer drive cam 5, causing the hammer 11 to rotate toward the type wheel 12.
At a position where the driven rotating shaft 4 has rotated a predetermined amount, the control lever 8 is locked to the locking pawl 6b on the ratchet 6 by the spring force, as shown in FIG. 6A. At this time, the sub lever 8a is moved by the driven disk 10.
Since the control lever 8 enters the notch 10a in the locking claw 6b, the locking of the control lever 8 to the locking pawl 6b is not prevented.

When the rotation of the ratchet 6 is inhibited by the locking of the control lever 8 in this way, the driven disk 10 rotates by the required rotation amount regulated by the arcuate elongated hole 10b from the time when the control lever 8 is locked. after,
The spring clutch mechanism is turned off and the hammer drive cam 5 stops rotating. In this stopped state, the type wheel rotation drive mechanism operates using the locked state of the control lever 8 as a trigger, and the type wheel 1
2 rotates in response to the rotation of the drive source.

Immediately before the desired symbol on the type wheel 12 reaches the printing position, the electromagnet is energized by a signal from the type position detector, and the control lever 8 and sub-lever 8a are activated by the locking pawl 6a and the notch, as shown in FIG. 6B. Part 10a
The spring clutch mechanism returns to the on state by releasing or disengaging, respectively, and the type wheel 12 stops and the hammer drive cam 5 rotates. After this rotation starts, the electromagnet is immediately deenergized, so that the rotational force toward the ratchet 6 is restored to the control lever 8. However, except when the control lever 8 is locked with the locking pawl 6b of the ratchet 6,
As shown in FIG. 6C, the sub-lever 8a comes into sliding contact with the circumferential surface of the driven disk 10 that rotates together with the ratchet 6 via the linking plate 14, etc., so the control lever 8 is separated from the circumferential surface of the ratchet 6 by an appropriate distance. In this separated state, the clutch for driving the type wheel is maintained in the OFF state. In this way, during rotation of the hammer drive cam 5, etc., the sub-lever 8a is in frictional contact with the circumferential surface of the driven disk 10, and this frictional force acts in the direction of winding and tightening the coil spring S, causing the spring clutch to be in the on state. is more certain.

As detailed above, according to this invention, the configuration is such that a cylindrical arbor is rotatably fitted around the outer periphery of the driven rotating shaft, and a ratchet provided with a locking portion on the outer periphery is rotated around the outer periphery of the arbor. A circular driven disk that can be freely fitted and has a notch on its outer periphery is fixed to the driven rotating shaft in close proximity to the ratchet, and one end of a coil spring wound around the outer periphery of the arbor is engaged with the arbor. the other end of the coil spring is locked on the driven disk side at a position where the notch and the locking part correspond, and each free end of the control lever and sub-lever, which are integrally provided with each other, is locked with the ratchet. and biasing toward the outer circumferential surface of the driven disk so that the free end of the sub-lever is slidably engaged with the outer circumferential surface of the driven disk, and the sub-lever is engaged with the outer circumferential surface of the driven disk. When the sub-lever is engaged with the notch, the free end of the control lever is separated from the outer peripheral surface of the ratchet and the locking part, and when the free end of the sub-lever is engaged with the notch, the free end of the control lever is separated from the outer peripheral surface of the ratchet and the locking part. Since the control lever is formed such that the latch portion engages with the locking portion, when the control lever is not locked with the locking portion of the ratchet and the driven rotating shaft is rotating, the ratch by the control lever is not engaged with the locking portion. Frictional contact with the circumferential surface is avoided, resulting in the effect that the spring clutch mechanism will not malfunction. Furthermore, when the spring clutch mechanism is in the ON state, even though the control lever is held at an appropriate distance from the ratchet, when the control lever is engaged with the locking part in the ratchet, the sub-lever cuts into the notch of the driven disk. By entering the part, it rotates by a predetermined amount, so
A practical effect is obtained in that the movement caused by this rotation can be used for clutch control of a type wheel rotation drive mechanism or the like.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a conventional spring clutch mechanism, Fig. 2 A, B, and C are explanatory diagrams of the operation of the same spring clutch mechanism, and Fig. 3 A, B are explanatory diagrams of the operation of another conventional spring clutch mechanism. , FIG. 4 is a plan view showing an embodiment of the spring clutch mechanism according to this invention, FIG. 5 is an exploded perspective view of the same spring clutch mechanism, and FIGS. 6A, B, and C are views of the spring clutch mechanism of FIG. 4. It is an operation explanatory diagram. 3... Drive arbor, 4... Driven rotating shaft, 5...
Hammer drive cam, 6... ratchet, 6b... locking pawl, 8... control lever, 8a... sub lever,
10... Driven disk, 10a... Notch, 11
... Hammer, 12 ... Type wheel, M ... Motor, S
……coil spring.

Claims (1)

[Scope of utility model registration request] A cylindrical arbor that is rotationally driven is rotatably fitted on the outer periphery of a driven rotating shaft, a ratchet having a locking portion on the outer periphery is rotatably fitted on the outer periphery of the arbor, and a notch is provided on the outer periphery. A circular driven disk is fixed to the driven rotating shaft in close proximity to the ratchet, one end of a coil spring wound around the outer periphery of the arbor is locked to the arbor, and the other end of the coil spring is fixed to the arbor. The notch and the locking portion are locked on the driven disk side at corresponding positions, and the free ends of the control lever and the sub-lever, which are integrally provided with each other, are urged toward the outer peripheral surfaces of the ratchet and the driven disk. The free end of the sub-lever is slidably engaged with the outer peripheral surface of the driven disk, and when the sub-lever is engaged with the outer peripheral surface of the driven disk, the free end of the control lever is slidably engaged with the outer peripheral surface of the driven disk. When the control lever is separated from the outer peripheral surface of the ratchet and the locking portion, and the free end of the sub-lever is engaged with the notch, the free end of the control lever is engaged with the locking portion. A spring clutch mechanism characterized in that the control lever is formed in the spring clutch mechanism.