JPS62178369A - Printer - Google Patents

Abstract

PURPOSE:To allow a printing hammer to strike a daisy wheel at a regular printing position, by a method wherein immediately when a fixed time has passed after the daisy wheel performing damped oscillation passed a regular stop position, a printing hammer is driven. CONSTITUTION:When the pulse for switching the last phase is inputted to a motor drive circuit 3, a stepping motor 1 is revolved by one step angle and however, a daisy wheel 2 executes damped oscillation utilizing a regular stop position as its center. At that time, an alternating current V appears in a resistor 35 and is compared with the voltage Vs held in a sample and hold circuit 51 by a comparator 50. After the comparison, the voltage outputted from a passing time point detecting circuit 5 trails and time t3 passes. Then, a drive signal is outputted from CPU 4 and a printing hammer 6d is driven with a printing hammer drive circuit 7. Just after time t4 has elapsed, the daisy wheel 2 is struck by the printing hammer 6d. Therefore, the time point at which the daisy wheel 2 is struck conforms to the time point at which the daisy wheel performing damped oscillation comes to the regular printing position thereof and the printing is carried out at the regular printing position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a printing device using daisy foil.

[Prior Art] A stepping motor that rotates a predetermined angle in response to a pulse for final phase switching does not immediately stop at a regular stop position because its rotor itself has inertia, but instead rotates around the regular stop position. After a damped vibration, it stops.

Therefore, in a printing device, when the daisy wheel is driven by the above-mentioned stepping motor, the daisy wheel follows the operation of the stepping motor.
It will take some time for it to come to rest.

For this reason, conventional printing devices use a printing hammer to
The timing to strike the daisy foil is set immediately after the scheduled time (-settling time + delay time) has elapsed from the final phase switching point, or immediately after the settling time has elapsed.

[Problems to be Solved by the Invention] However, the conventional printing device is configured to strike the daisy foil with a printing hammer immediately after a scheduled time elapses from the final phase switching point or immediately after a settling time elapses. If the torque of the Ste-Novig motor used varies and the damped vibration characteristics differ, there is a problem that the normal printing position and the position where the daisy wheel is struck by the printing hammer do not match.

Therefore, the printing position may shift.

[Means for Solving the Problems] The object of the present invention is to enable a printing hammer to strike a daisy wheel at a regular printing position. After the daisy wheel is rotated by the final phase switching, the passing point detection means detects the passing point of the daisy wheel at the normal stop position, and then, immediately after a predetermined period of time has elapsed from the detected passing point, the printing hammer driving means The printing hammer is driven to strike the daisy foil.

[Example code] 1 and 2 show an embodiment of the invention.

In the figure, 1 is a four-phase unipolar stepping motor that rotationally drives a daisy wheel 2, and only stator windings 10 to 13 are shown in FIG. 2. 3 is a motor drive circuit that drives the stepping motor 1, and a transistor 31)-33
, is composed of resistors 34 and 35, and together with the CPU 4,
A motor drive means that drives a stepping motor by phase cutting tQ? It constitutes v1. The stepping motor 1 is excited in two phases. Collectors of the transistors 30-33 are connected to stator windings 10-13, respectively,
The emitter of transistor 3111.31 and the emitter of transistor 32j3 are each connected to ground via a resistor 34.35. Further, a pulse signal for two-phase excitation is inputted from the CPU 4 to the bases of the transistors 30 to 33. 5, after the final phase switching,
A passing time detection circuit serving as a passing time detection means for detecting the passing time of the regular stop position of the daisy wheel 2, which is composed of a comparator 50 and a sample and bold circuit 51, and is configured to detect the voltage of the resistor 35 and the sample and hold circuit 51 is compared with the voltage of 6 is a drive solenoid,
6a is a yoke, 6b is a movable return spring, 6C is a movable body, 6
d is a printing hammer that strikes the daisy foil 2; 7 is a printing hammer driving circuit that drives the printing hammer 6d, which together with the CPU 4 constitutes printing hammer driving means H that drives the printing hammer 6d immediately after a predetermined time has elapsed from the passing time detected by the passing time detection means 5. ing. 8 is an ink ribbon, and 9 is paper set on the platen 14.

Next, to explain the operation, when a pulse for final phase switching is input to the motor drive circuit 3, the stepping motor 1 rotates by one step angle, but since the rotor itself has inertia, the daisy wheel 2 does not immediately stop at the normal stop position, but performs a damping motion around the normal stop position. At this time, the AC voltage V (period tl) shown in FIG. 3(a) is applied to the resistor 35.
) appears and this voltage is passed through the sample-and-hold circuit 5.
It is compared with the voltage Vs held at 1 by a comparator 50. However, the voltage VS is the voltage when the daisy wheel 2 is located at the normal printing position.

After the comparison, the passing point detection circuit 5 outputs the voltage shown in FIG. The hammer drive signal shown in FIG. 3(C) is input to the print hammer drive circuit 7, and the print hammer drive circuit 7 starts driving the print hammer 6d. Immediately after time t4 has elapsed since the printing hammer 6d started to be driven, that is, as described above,
Time t 1 + t 2 (= t 3 + t 4) from the time when the output voltage of the passing point detection circuit 5 falls to H mustard.
Immediately after the passage of time, the daisy foil 2 is struck by the printing hammer 6d (see FIG. 3(d)), where 11 is the period of the alternating current voltage V appearing on the resistor 35, and t2 is the actual period of the alternating current voltage V and the daisy foil 2. This is the difference in position from the damped vibration of . tl and t2 are constant values determined by the stepping motor 1 and the daisy wheel 2.

Therefore, the daisy wheel 2 is hit by the printing hammer 6d.
The time of impact coincides with the time when the daisy foil 2, which is undergoing damped vibration, is located at the normal printing position (Fig. 3(d)).
), (e)) Printing will be performed at the regular printing position.

[Effects of the Invention] This invention is configured to drive the printing hammer immediately after a predetermined period of time has elapsed from the time when the daisy foil in damped vibration passes through the normal stop position. It has the effect of being able to hit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a circuit diagram showing a specific example of the motor drive circuit 3 and passage detection circuit 5. FIGS. FIG. 3(d) is a diagram showing the relationship between the stroke of the printing hammer and time, and FIG. 3(e) is a diagram showing an example of damped vibration of the daisy foil. In the figure, 1... stepping motor 2...
Dizzy wheel 3... Motor drive circuit 4... CPU 5... Passage point detection circuit 6d... Print hammer 7... Print hammer drive circuit M... Motor drive means H... Print hammer drive It is a means.

Claims (1)

[Claims] A stepping motor that rotates the daisy wheel,
a motor drive means for driving this motor by phase switching; a passing time detection means for detecting the time point at which the daisy wheel passes through the normal stop position after the final phase change; a printing hammer for striking the daisy wheel; and printing hammer driving means for driving the printing hammer immediately after a predetermined period of time has elapsed from the passing point detected by the detection means.