JPS631191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small serial printer using a type wheel, and more particularly to a printing mechanism that prints by swinging the type wheel.

A conventional serial printer using a type wheel uses a step motor to rotate and selectively stop the type wheel, and then prints by striking the stopped type with a hammer energized by a solenoid. This printing method requires expensive step motors and solenoids, which not only increases costs, but also has the disadvantage that this type of transducer has a low electrical conversion efficiency, which leads to increased power consumption. had.

The present invention has been made in view of these drawbacks, and its object is to provide a serial printer that is low in cost, has excellent print quality, and has quiet printing noise.

The gist of the present invention is a main shaft 1 rotated by a motor, a drive gear 2 that rotates integrally with the main shaft 1 and can slide in the thrust direction, and a driven gear 5 and a driven gear that mesh with the drive gear on the side. 5, a type ring 3 having serrated teeth 6 that rotates integrally with the serrated teeth 6 and having type 4 on the outer periphery, a locking pawl 8 that engages with and disengages from the serrated teeth 6, and the type ring 3 and the locking pawl 8. a swinging lever 11 which has an opening 12 at its end and is swingably inserted into the main shaft 1; a return spring 10 that applies a spring force to the type wheel 8; a platen 15 that is placed close to the type wheel 3 and has printing paper 16 disposed on its outer periphery; and a detection section that outputs a synchronization signal corresponding to the position of the type on the type wheel 3. 18, and an eccentric cam 1 inserted into the opening 12 of the swing lever 11 and rotatable.
3, and the eccentric cam 13, the locking pawl 8, and the opening 12 are such that when the eccentric cam 13 rotates in response to the output of the synchronization signal from the detector 18, the eccentric cam 13 first engages the locking pawl. The locking pawl 8 rotates by pressing the outer circumferential surface of the opening 12, jumps into the serrated teeth 6, and locks the type ring 3, and then the eccentric cam 13 presses the side wall of the opening 12 and swings. The rotation timing of the locking claw 8 by the eccentric cam 13 and the swing timing of the swing lever 11 are adjusted such that the swing lever 11 swings around the main shaft 1 and moves the type wheel 3 toward the platen 15 to print. This is a printing mechanism of a serial printer characterized by being arranged in a positional relationship that shifts the printing mechanism.

Hereinafter, the present invention will be explained using figures. FIG. 1 is a side cross-sectional view showing the printing mechanism of the present invention, in which numeral 1 denotes a main shaft having a notch, which extends in the thrust direction and is rotated by a motor (not shown). Reference numeral 2 denotes a drive gear which rotates together with the main shaft 1, but is inserted so that it can also slide in the thrust direction. Reference numeral 3 denotes a type wheel, which is rotatably supported on a shaft 7 and has type characters 4 on its outer periphery, a driven gear 5 meshing with the drive gear 2 on its side, and serrated teeth 6 provided corresponding to the positions of the type characters 4.

8 is a locking pawl that engages with the serrated teeth 6 and locks the type ring 3.
stop rotating. 9 is the shaft, 10 is the return spring. 11
A swing lever is inserted to be able to swing around the main shaft 1, and has a shaft 7 that pivotally supports the type ring 3 and a shaft 9 that pivotally supports the locking pawl 8.

Reference numeral 13 is an eccentric cam which is inserted into the opening 12 of the swinging lever 11, gives swinging motion to the swinging lever 11 in the directions of arrows A and B, and also engages with the locking pawl 8 to move the swinging lever 11 in the direction of arrow C. give movement. In addition, the eccentric cam 13
The rotation is obtained from the same motor that rotates the main shaft 1, but it is controlled to rotate and stop at a speed sufficiently higher than the rotational speed of the type wheel 3 by a one-turn clutch (not shown). 14 is an ink roll that supplies ink to the type 4; 15 is a platen; 16 is printing paper; and 17 is an auxiliary roller that presses the printing paper 16 against the platen 15. A detector 18 is composed of a disc 19 having a slit and a photocoupler 20, and outputs a synchronization signal corresponding to the position of the type on the type wheel 3.

Next, the operation will be explained. When the desired type appears at the printing position on the type wheel 3 rotated by the main shaft 1, the eccentric cam 1
Activate the one-turn clutch in step 3 and rotate (in the direction of arrow D)
When the locking pawl 8 is rotated in the direction of arrow C, it engages with the serrated teeth 6 and locks the type ring 3. On the other hand, since the eccentric cam 13 causes the swing lever 11 to swing in the direction of arrow A, the type wheel 3 is pressed against the printing paper 16 on the platen 15 in a stopped state to print.

FIG. 2 is a diagram illustrating this printing operation in more detail. Assuming that the rotation angle of the eccentric cam 13 is α, the operating angle of the locking pawl 8 in the direction of arrow C is θ ₁ , and the operating angle of the swing lever 11 in the directions of arrows A and B is θ ₂ , as shown in the graph of FIG. There is a relationship. As can be seen from Fig. 1, the structure consists of a swing lever 11, a locking pawl 8, and an eccentric cam 1.
Since the sliding position with respect to 3 is shifted by approximately π/2,
Each movement occurs with a shift of approximately π/2 as shown in the graph. This means that the locking pawl 8 first jumps into the serrations and stops the type wheel 3, and t ₁ in the graph
corresponds to On the other hand, the swing lever 11 starts swinging during _t1 , but since there is a delay of π/2 from the locking pawl 8, the actual printing operation occurs corresponding to the graph _t2 .

In the printing mechanism of the present invention shown in FIG. 1, the following considerations must be made. Since this mechanism is an application of a type of differential gear, the type wheel 3 rotates on its own axis by the drive gear 2 and revolves around the main shaft 1. When the rotation of the type wheel 3 is stopped by the locking pawl 8, it starts to revolve at a rotational speed determined by the ratio of the number of teeth between the drive gear 2 and the driven gear 5. It is necessary that this revolution speed and the speed of the rocking motion achieved by the eccentric cam 13 be approximately equal. Alternatively, it is also possible to elastically connect the driven gear 5 and the serrated teeth 6 as a double structure to absorb the unbalance of the revolution and rotation of the type wheel 3.

By moving the type wheel 3 and the locking pawl 8, which are pivotally supported on the swing lever 11 that performs such an operation, together with the drive gear 2, in the thrust direction several orders of magnitude over the main shaft 1 and the eccentric cam 13, , it is possible to print as many digits as possible. As for the step feed mechanism, the already known lead screw type or the wire winding type can be easily applied.

As detailed above, in the present invention, expensive mechanisms such as a step motor that rotates and selectively stops the type wheel and a solenoid that energizes the stopped type and strikes it with a hammer are no longer required. Since it is basically based on the use of a rotating motor and an eccentric cam, the cost can be reduced, and since the motor can rotate continuously, it can be used with step motors, solenoids, etc. This provides much more efficient drive than pulse drive.

In particular, in the present invention, the printing quality is excellent because printing is performed after the rotation of the type wheel is stopped. This timing can be used skillfully and appropriately.
In other words, the eccentric cam 13 only rotates in response to the signal from the detector 18. First, the locking pawl 8 is pressed and rotated to lock the eccentric cam 13 in the serrated teeth 6. After the rotation, the side wall of the opening 12 is pressed to rotate the swing lever 11 so that the type 4 can be printed on the printing paper 16. That is, by simply rotating the eccentric cam 13, which is an extremely simple operation, it is possible to cause the locking pawl 8 to lock the serrated teeth 6, and similarly to swing the swing lever 11 to print the letters 4. , each operation was performed reliably by shifting the appropriate timing, and printing quality was able to be significantly improved. Also, this structure is simply an eccentric cam 1
It is based on the skillful use of 3, and is extremely simple and stable in operation.

In addition, the swing lever 11 due to the rotation of the eccentric cam 13
Since the oscillation is like a sine curve, no sudden printing force is applied when printing the print 4, so the printing sound is quiet and damage to the printing paper 16, the print 4, etc. is prevented. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the printing mechanism of a serial printer according to the present invention, in which 1 is a main shaft, 2 is a drive gear,
3 is a type wheel, 5 is a driven gear, 6 is a serrated tooth, 8 is a locking pawl, 11 is a swing lever, 13 is an eccentric cam, 1
4 is an ink roller, 15 is a platen, 16 is printing paper, and 18 is a detector. FIG. 2 is an explanatory diagram of the operation of the printing mechanism shown in FIG. 1.

Claims (1)

[Claims] 1 A main shaft 1 rotated by a motor, a drive gear 2 that rotates integrally with the main shaft 1 and can slide in the thrust direction, a driven gear 5 that meshes with the drive gear on the side, and a driven gear 5 integrated with the driven gear 5. A type wheel 3 having rotating serrations 6 and having type 4 on its outer periphery.
, a locking pawl 8 that engages and disengages from the serrated teeth 6, and a locking pawl 8 that supports the type ring 3 and the locking pawl 8, each having an opening 12 at the end thereof, and is swingably inserted into the main shaft 1. a swinging lever 11 to be attached, a return spring 10 that applies a spring force to the locking pawl 8 so that the locking pawl 8 moves away from the serrated teeth 6, and a return spring 10 disposed near the type ring 3 and printing on the outer periphery. A platen 15 on which paper 16 is placed, a detector 18 that outputs a synchronization signal corresponding to the position of the type on the type wheel 3, and the opening 12 of the swing lever 11.
It has an eccentric cam 13 inserted therein and rotatable,
The eccentric cam 13, the locking pawl 8, and the opening 12 are such that when the eccentric cam 13 rotates in response to the output of the synchronization signal from the detector 18, the eccentric cam 13 first presses the outer peripheral surface of the locking pawl 8. Then, the locking pawl 8 rotates and jumps into the serrated teeth 6 to lock the type wheel 3. After that, the eccentric cam 13 presses the side wall of the opening 12, and the swing lever 11 moves to the main shaft 1. The positional relationship is such that the rotation timing of the locking pawl 8 by the eccentric cam 13 and the rotation timing of the swing lever 11 are shifted so that the type wheel 3 is oscillated around , and printing is performed by moving the type wheel 3 toward the platen 15 side. A printing mechanism of a serial printer characterized by a configuration.