JPH02267Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a type selection mechanism for a type serial printer.

Conventionally, in this type of type selection mechanism, when the frictional load in the rotational direction is small, if the stepping motor for selecting type in the rotational direction is controlled only by an appropriate combination of pulse timings, variations in motor characteristics and drive circuit characteristics may occur. Due to this, a certain amount of vibration inevitably appears when the engine is stopped, and it is difficult to converge the vibration in a short period of time.

However, if a frictional load is applied from the outside in order to quickly converge this vibration, a problem arises in that the load on the type selection mechanism in the direction of the rotational axis also increases in a type selection mechanism that also selects type in the direction of rotation. It was hot.

The present invention uses a friction adding mechanism to converge the vibrations caused when the stepping motor stops due to variations in motor characteristics even if the stepping motor is driven at optimal pulse timing, and does not affect type selection in the direction of the rotation axis. The present invention provides an efficient and highly accurate type selection mechanism.

There are two ways to reduce vibration when a stepping motor stops, such as optimizing the pulse timing and performing so-called profile control, and applying an external friction load. In combination, the stepping motor can be controlled more reliably and efficiently. Furthermore, a mechanism is adopted in which friction applied from the outside acts only in the direction of rotation and does not create a load in the direction of the rotation axis.

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIGS. 1 and 2, one embodiment of the present invention includes a stepping motor 1 for selecting type in the rotational direction.
, a control unit 2, and a type selection mechanism 3 in the direction of the rotation axis.
, print wheel 4, spring 5, and U
It includes a pulley 6 having a groove and a presser fitting 7.

Stepping motor 1 for selecting type in rotation direction
is driven by a current supplied from the control unit 2 through a cable 8, and rotates a print wheel 4 which is positioned and removably mounted on a pulley 6 fixed to a motor shaft by a protrusion 9. By this, type selection in the direction of rotation is performed.
The rotational axis direction type selection mechanism 3 moves the motor shaft of the stepping motor 1 for rotational type selection up and down, thereby moving the print wheel 4 attached to the motor shaft up and down to select type in the rotational axis direction. Let's do it. In this way, type selection in the direction of the rotational axis is performed by directly moving the motor shaft of the stepping motor up and down, so a mechanism that applies a frictional load directly to the motor shaft would also apply a frictional load in the direction of the rotational axis, causing the rotational It is difficult to apply frictional load only in one direction.

Therefore, the following mechanism is adopted to solve this problem. The spring 5 constitutes a friction adding mechanism together with a pulley 6 having a U-shaped groove on its outer periphery and a presser fitting 7. Spring 5 is in initial state 5'
In the expanded state, the pulley 6 is applied to the U-shaped groove of the pulley 6, and the restoring force of the spring 5 generates a frictional force between the pulley 6 and the pulley 6. Therefore, a frictional load is applied to the stepping motor 1 for character selection in the rotating direction. When the stepping motor 1 for character selection in the rotational direction is driven with the optimized pulse timing generated by the control unit 2, the vibration in the rotational direction that occurs at the stop of the motor due to variations in motor characteristics, etc., is suppressed by the friction addition described above. The mechanism allows it to converge in a short time.

The support spring 5 is designed to be freely rotatable in the vertical direction around the part to which it is attached by the presser metal fitting 7. Therefore, even if the pulley 6 moves up and down in conjunction with the vertical movement of the print wheel 4 when selecting type in the direction of the rotation axis, the load applied to the type selection mechanism 3 in the direction of the rotation axis is the same as in the case without the friction adding mechanism. Since there is almost no difference in comparison, the type selection mechanism in the rotational axis direction can be the same as in the case without the friction addition mechanism. Also, the friction is the spring 5
Because it acts far from the fulcrum, pulley 6
A stable friction load can be obtained even if the friction goes up and down.

As explained above, the present invention eliminates vibrations in the rotational direction that occur due to variations in motor characteristics even when pulse timing is optimized, by using a friction adding mechanism in the rotational direction that does not increase the load in the rotational axis direction. To realize an efficient and highly accurate type selection mechanism through convergence.

[Brief explanation of drawings]

1 and 2 are a plan view and a side view of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Stepping motor for selecting type in the direction of rotation, 2... Control section (including a drive circuit), 3... Character selection mechanism in the direction of rotation axis, 4... Print wheel, 5... Spring, 5'... ... Spring initial state, 6 ... U-shaped grooved pulley, 7 ... Holder metal fitting,
8... Cable, 9... Print wheel positioning protrusion.

Claims (1)

[Scope of utility model registration request] a print wheel holding a plurality of print characters in the circumferential direction of upper and lower rows; a rotational direction type selection mechanism that rotates the print wheel around its rotation axis to select one of the print characters on the same circumference; a rotary axis direction type selection mechanism for moving the print wheel in the rotation axis direction to select the upper or lower circumferential type type; and a rod-shaped type having one end in contact with the rotation axis of the print wheel and applying a load to the rotation. The present invention is characterized by comprising a spring, and a holding member that rotatably holds the rod-shaped spring that engages with the other end of the rod-shaped spring and rotates following the movement of the print wheel in the direction of the rotation axis. Type selection mechanism.