JPH0688411B2 - Printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial impact type printer using a type wheel.

2. Description of the Related Art In recent years, in order to speed up printing, a spoke of a conventional flat type wheel has been replaced with a printing device using a petal type print wheel having a type at the tip of a radially formed spoke. A printing device has been developed which uses a type wheel in which a portion is bent to form a cup shape to reduce the moment of inertia. Since the type wheel of this type wheel has two stages, the type can be selected by two movements of rotation and shift, the type moment can be reduced, the type selection time can be shortened, and high-speed printing becomes possible.

Hereinafter, an example of the above-described conventional printing apparatus will be described with reference to the drawings.

FIG. 4 shows a conventional printer. In FIG. 4, 80 is a platen for holding the printing paper 81, 82 is a type wheel, and a plurality of spokes 83 extend to form a cup shape.
Printed characters 84a and 84b are formed on the steps. The type wheel 82 is removably attached to a mount 86, and the mount 86 is rotatably and vertically supported on a shaft 88 of a motor 87 that rotates the type wheel 82 to select a type. A rotation transmission member 89 is fixed to the shaft 88 of the motor 87, and the pin 90 fixed to the rotation transmission member 89 and the projection 91 of the mount 86 are movable relative to each other in the rotation axis direction of the motor 87. Because of the meshing, the rotation of the motor 87 is transmitted to the type wheel 82 via the mount 86, but the type wheel 82 can freely move up and down.

92 is a rotary solenoid, the shaft of which is an eccentric shaft
93 is installed. The eccentric shaft 93 is a shift lever rotatably attached to a fixed portion (not shown) with a pin 94.
A roller 96 which is fitted in a long hole formed at one end of the 95, and the other end of the shift lever 95 is fitted in the groove 86a of the mount 86.
Is provided. The rotation of the rotary solenoid 92 causes the shift lever 95 to rotate about the pin 94 to move the mount 86 up and down, thereby giving the type wheel 82 a displacement equal to the vertical pitch of the type characters 84a and 84b.

When printing, the rotation of the motor 87 and the rotary solenoid 92 causes the type wheel 82 to rotate and move up and down to select a type, and the printing hammer 97 operates to activate the type 84.
Press a (or 84b) toward the print paper 81. Then, since the spokes 83 have appropriate elasticity, the print characters 84a (or 84b) are pressed against the printing paper 81. Type 84a (or
Since an ink ribbon 98 is provided between 84b) and the printing paper 81, printing is performed.

Problems to be Solved by the Invention However, in the conventional printing apparatus configured as described above, a complicated mechanism is required for the rotation and vertical movement of the type wheel, which is not suitable for downsizing of the apparatus. Moreover, structurally, there are problems that the frictional force is large and the load on the motor is large, and that there is backlash due to wear, the positioning accuracy is reduced, and noise is generated.

In view of the above problems, the present invention provides a printing apparatus that is suitable for downsizing, is excellent in reliability due to reduction of friction and wear, and has a quiet sound and a high printing speed.

Means for Solving the Problems In order to solve the above-mentioned problems, the printing apparatus of the present invention uses a shaft as a driving means for selecting upper and lower type characters of a type wheel having type characters provided in upper and lower two stages. It uses an electromagnetic solenoid with a movable iron core supported so that it can rotate and move up and down, and this movable iron core holds a type wheel and moves up and down by energizing and interrupting an exciting current. Is configured. Then, in a process in which an exciting current is passed through the electromagnetic solenoid to move and hold the movable iron core to an upper position, the exciting current is shut off to move the movable iron core to a lower position for a predetermined time after the current is shut off. After the lapse of time, the electromagnetic solenoid is controlled to be energized for a predetermined time.

The present invention is suitable for downsizing of the apparatus because the above-mentioned configuration does not require a complicated mechanism for vertical movement because the type wheel is directly driven up and down by an electromagnetic solenoid without using a complicated mechanism. Therefore, it is possible to prevent the occurrence of backlash due to wear, which lowers the positioning accuracy and noise. Further, the frictional force and the inertial load are reduced, and the load on the motor can be reduced.

Embodiment A printer according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a printer according to an embodiment of the present invention. In FIG. 1, reference numeral 40 is a platen for holding a printing paper 41. 42 is a type wheel, which is a disk part
Vertically spaced spokes around the outer periphery of 43
44 are extended, and the characters 45a and 45b are formed on the outer tip of each of the spokes 44 in upper and lower two stages. Type wheel 4
A gear 46 is formed on the outer circumference of the second disc portion 43 and meshes with a gear 48 fixed to the rotation shaft of a motor 47. The type wheel 42 is attached to a holding member 50 fixed to a movable iron core 49. When the electromagnetic solenoid 51 operates to move the movable iron core 49 up and down, the type wheel 42 also moves up and down.

The motor 47 is controlled by a control circuit (not shown) based on a signal from the detector 52 which detects the rotational position of the gear 48 in order to control the rotational position of the type wheel 42. gear
The type 48 has such a thickness that it keeps meshing with the gear 46 of the type wheel 42 even when the type wheel 42 moves in the vertical direction.

The type wheel 42 selectively stops the type 45a (or 45b) to be printed at the position in front of the printing hammer 53 by the action of the motor 47 and the electromagnetic solenoid 51. Printing hammer
53 is moved to the right in the figure by a hammer drive mechanism (not shown), and pushes the type 45a (or 45b) toward the printing paper 41. Then, since the spokes 44 have appropriate elasticity, the print characters 45a (or 45b) are pressed against the printing paper 41. Since an ink ribbon 54 is provided between the type 45a (or 45b) and the printing paper 41, printing is performed.

FIG. 2 is a sectional view of the electromagnetic solenoid 51. A shaft 55 fixed to the center of a fixed base 54 has a cylindrical rotor 56 made of a magnetic material, and a movable iron core 49 also made of a magnetic material.
Are supported in a vertical positional relationship. Shaft 55
Since the surface of is coated with a thermosetting resin containing molybdenum disulfide, the rotor 56 and the movable iron core 49 can freely rotate on the shaft 55. The movable iron core 49 can also move in the axial direction of the shaft 55. A coil spring 57 is provided between the flange portion 55a of the shaft 55 and the movable iron core 49, and urges the movable iron core 49 downward. The movable iron core 49 has an E-ring 58 whose lower end is attached to the shaft 55 by the urging force of the coil spring 57 and its own weight.
It has stopped at the position where it hits. Since the resin washer 59 having a small frictional resistance is sandwiched between the movable iron core 49 and the E ring 58, the rotational resistance of the movable iron core 49 is small.

A holding member 50 is fixed to the lower portion of the movable iron core 49, and a V-shaped groove is provided near the lower end. The type wheel 42 is held on the holding member 50 by the force of the spring 60 attached to the type wheel 42 pressing the slope 49a of the V-shaped groove.

A hollow exciting coil 61 is provided around the rotor 56 and the movable iron core 49, and yokes 62, 63 made of a magnetic material are provided around the exciting coil 61.
Are arranged to surround.

When the exciting coil 61 is energized, the movable iron core 49 receives an upward force in the figure, moves upward while compressing the coil spring 57, and attracts the rotor 56. The rotor 56 receives a downward force from the movable iron core 49 due to the biasing force of the coil spring 57.
The lower end surface of 56 is stably held on the flange portion 55a of the shaft 55. When the movable iron core 49 is attracted to the rotor 56, a sufficient attracting force is generated with a small current, so that the voltage applied to the exciting coil 61 can be lowered. In order to print the upper type 45a and the lower type 45b of the type wheel 42 in line on the same print line, the amount of vertical movement of the movable iron core 49 is adjusted by the thickness of the resin washer 59.

As shown in FIG. 2, the first position is the position where the type wheel 42 is lowered such that the upper type 45a faces the tip of the print hammer 53, and the lower type 45b faces the tip of the print hammer 53. When the position where the type wheel 42 is raised is set to the second position so that the exciting coil 61 is energized when the type wheel 42 is in the first position, an electromagnetic force is generated and the movable iron core 49 is attracted upward. Then, the type wheel 42 is attracted to the rotor 56 and moved to the second position to hold it.

3A and 3B show the displacement when the movable iron core 49 moves from the second position to the first position, and the exciting coil 61 at that time.
It shows the applied voltage applied to. When the energization of the exciting coil 61 for holding the movable iron core 49 at the second position is stopped, the movable iron core 49 starts moving downward by its own weight and the action of the coil spring 57. When the exciting coil 61 is energized again for a short period of time after the stop of energization, an electromagnetic force is generated to brake the movement of the movable iron core 49, the speed at which it collides with the lower end decreases, and the collision noise decreases. In addition, the amount of rebound also decreases, and it is possible to settle in a short time and immediately move to the next operation. If the exciting coil 61 is not energized again after a lapse of a predetermined time after the energization is stopped, the speed of collision with the lower end increases as shown by the broken line in the figure, and the amount of rebound also increases. Therefore, the impact noise becomes loud and the settling time becomes long.

As described above, according to the present embodiment, it is possible to directly move the movable iron core, to which the holding member for mounting the type wheel is fixed, up and down by magnetic force in a non-contact manner. Further, the number of operating members is reduced, reliability is improved, noise is suppressed, and the device can be downsized. Further, since the rotational resistance when rotating the type wheel is small and the load inertia is small, the load of the motor is reduced.

EFFECTS OF THE INVENTION As described above, the present invention is supported on a shaft so as to be rotatable and movable up and down as a driving means for selecting upper and lower type characters of a type wheel having two upper and lower type characters. Using an electromagnetic solenoid with a movable iron core, a type wheel is held on this movable iron core to pass an exciting current.
When the movable iron core is configured to move up and down by shutting off, the exciting current is passed through the electromagnetic solenoid to move and hold the movable iron core to the upper position, and then the exciting current is shut off to move the movable iron core to the lower position. In the process of moving to, the control is made so that the electromagnetic solenoid is energized for a certain period of time after the current has been cut off, so there is less friction and wear, and reliability is excellent. It is possible to provide a small-sized printing device having a high speed.

[Brief description of drawings]

FIG. 1 is a side view showing a printing apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of an example of an electromagnetic solenoid used in the present invention, and FIGS. 3 (a) and 3 (b) show the electromagnetic solenoid. FIG. 4 is a side view showing an example of a conventional printing device for explaining the operation, and FIG. 42 ... Type wheel, 44 ... Spoke, 45a, 45b ... Type, 49
… Movable iron core, 51… Electromagnetic solenoid.

Claims (1)

[Claims] 1. A type wheel having upper and lower two-stage type characters,
In a printer having a motor for rotating the type wheel to select a type, and a drive unit for moving the type wheel up and down to select the upper and lower type characters, the drive unit is a shaft. An electromagnetic solenoid having a movable iron core rotatably and vertically movably supported on the movable iron core, the movable iron core holding the type wheel and being configured to move up and down by energizing and interrupting an exciting current, and In the process of shutting off the exciting current and moving the movable iron core to the lower position from the state where the moving iron core is moved and held at the upper position by passing the exciting current to the electromagnetic solenoid, a predetermined time has elapsed after the current is shut off. To the electromagnetic solenoid for a predetermined time.