JPH058110B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printing device, and more particularly to a printing head feeding mechanism and feeding control when the printing head is moved by a wire or a belt.

Prior Art In a conventional printing device of this type, a printing head is held on a head base that is slidable in a direction parallel to a platen, and a looped wire or belt is stretched by a drive pulley and an idler pulley. The belt is fixed to the head base with a belt holder, and a drive motor rotates a drive pulley to drive the belt, thereby moving the print head. .

In the print head drive described above, the acceleration of the print head is provided by the difference in tension between the tension side and the slack side of the belt, which is generated by rotating the drive pulley. However, since the belt is generally an elastic body and expands or contracts between the tension side and the flexure side, the movement of the motor's rotating shaft and the movement of the print head do not correspond 1:1, and the print head cannot be driven. This results in a delay in following the rotation axis of the motor.

When the rotary shaft of the drive motor is controlled by a step motor or when the movement of the rotary shaft is detected by a sensor for closed loop control, the above-mentioned print head delay is ignored. Even when print head delays are taken into account, it is difficult to achieve accurate print head advance by considering them within a purely theoretical framework.

It has also been considered to provide a sensor that detects the position of the print head and control the head position to move in a predetermined manner based on the output of this sensor, but such sensors are expensive and If the head position is controlled only by the sensor, the rotation of the motor shaft becomes unstable as the belt expands and contracts.
In order to solve this problem, it is necessary to perform complex control by taking into account the outputs of both the motor shaft sensor and the head position sensor, making the control mechanism complicated and even more expensive. .

OBJECT OF THE INVENTION The object of the invention is to solve the above-mentioned conventional drawbacks and
An object of the present invention is to provide an inexpensive printing device that enables simple and accurate feed control by detecting the tension of a belt or the like and controlling the tension so that the change pattern becomes ideal.

Structure of the Invention The printing device of the present invention includes a print head that is slidably held parallel to a platen, a loop-shaped wire or belt for moving the print head, and a drive that tensions the wire or belt. In a printing device equipped with a drive pulley, an idle pulley, and a drive motor that rotates the drive pulley, a tension sensor or a pressure sensor that locks the idle pulley to the frame, and a tension sensor or pressure sensor that locks the idle pulley to the frame, and a A storage unit that stores an ideal tension change pattern; and a control unit that compares the tension change pattern read from the storage unit with the output of the tension sensor or pressure sensor to control the drive motor. It is characterized by

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. That is, the printing head 1 is mounted on the head base 2 which is slidably held by the guide shafts 3 and 4, and the loop-shaped belt 8 is attached to the head base 2 using the belt presser 5 and the screw 9.
is pulled by the drive pulley 7 and the idler pulley 10, and the drive pulley 7 is pulled by the drive motor 6.
When the printer is rotated, the head base 2 is pulled by the belt 8 and slid by the guide shafts 3 and 4, and the print head 1 is moved from side to side in the figure parallel to a platen (not shown).

The idle pulley 10 is attached to a pulley holder 11
The pulley holder 11 is held by a pressure sensor 12
It is attached to the frame 13 via. Therefore, the driving pulley 7 is rotated by the driving motor 6.
When the belt is rotated counterclockwise, as shown in FIG. (ignoring torque loss and weight of belt 8) Tb−Ta
It starts moving in the direction of the idle pulley 10 under the tension of. Here, the idle pulley 10 has
As shown in Figure 3A, a tension of 2 Tb is applied. A pressure sensor 12 detects the tension applied to the idler pulley 10.

FIG. 3B is a diagram showing the relationship between the displacement 21 of the motor shaft and the displacement 22 of the print head when the print head 1 is ideally operated from the start of operation to the stop. Print head displacement 2
The difference between 2 and 23 indicates the elongation of the belt. The horizontal axis indicates time from the start of driving. At the same time, motor shaft displacement 2
1. Print head displacement 22 is also expressed as normalized, but motor shaft displacement 21 and print head displacement 22
The difference 23 represents the expansion and contraction of the belt, and this multiplied by the belt spring constant becomes the tension difference for driving the print head. On the other hand, the tension 2Tb changes as shown in simultaneous C. This tension corresponds to the pressure (or tension) T detected by the pressure sensor 12. Therefore, the pressure T detected by the pressure sensor 12
However, if the motor shaft is driven so that the relationship shown in FIG. Ru.

Therefore, in this embodiment, a pressure pattern storage memory storing the ideal pressure pattern shown in FIG. 3C is prepared, and as shown in FIG. The microprocessor 25 inputs the pressure sensor 12
The output is compared with the read data from the pressure pattern storage memory 24, and the drive motor 6 is driven via the motor driver 26 in a direction that reduces the difference. Note that the above pressure pattern is based on the print head device,
Several types of ideal patterns are prepared depending on the direction of movement, and when comparing the ideal pattern and the output of the pressure sensor 12, depending on the difference in initial tension, the ideal pattern is biased by the difference in initial tension, etc. It shall be used with appropriate changes.

Note that the same applies even if the belt 8 is a wire, and it is desirable for the drive motor 6 to be a servo motor or a step motor with a sensor that can know position information in order to ensure accuracy of position control. Of course.

In this embodiment, by controlling the drive motor 6 so that the pressure applied to the pressure sensor 12 has an ideal pressure pattern, it is possible to perform stable and accurate control that takes into account the expansion and contraction of the belt 8. There is an effect that it can be done.

Effects of the Invention As described above, in the present invention, a tension sensor or a pressure sensor is provided to detect the tension applied to the idle pulley that tensions the belt, and the tension (or pressure) applied to the sensor is adjusted to an ideal pattern. Since the drive motor is configured to drive as follows, it is possible to perform stable and highly accurate control with a simple configuration that takes into account belt elongation.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure shows the relationship between the rotation of the driving pulley and the tension on the tension side and the deflection side of the belt in the above embodiment, Figure 3A shows the tension applied to the idle pulley in the above embodiment, and Figure B shows the belt FIG. 4 is a diagram showing an ideal relationship between the displacement of the motor shaft and the displacement of the printing head, C is a diagram showing an example of an ideal pressure pattern, and FIG. 4 is a block diagram showing the control section of the above embodiment. In the figure, 1: print head, 2: head base, 3, 4: guide shaft, 5: belt holder,
6: Drive motor, 7: Drive pulley, 8: Belt, 9: Screw, 10: Idle pulley, 11: Pulley holder, 12: Pressure sensor, 13: Frame, 21: Motor shaft displacement, 22: Print head displacement, 23: belt elongation, 24: pressure pattern memory, 25: microprocessor, 26: motor driver.

Claims (1)

[Claims] 1. A print head slidably held parallel to the platen, a loop-shaped wire or belt for moving the print head, a drive pulley and an idle pulley for tensioning the wire or belt, and the drive In a printing device equipped with a drive motor that rotates an idle pulley, a tension sensor or a pressure sensor that locks the idle pulley to a frame, and an ideal tension change pattern of the belt or the like when the print head moves are stored. A printing device comprising: a storage section; and a control means for controlling the drive motor by comparing the tension change pattern read from the storage section with the output of the tension sensor or the pressure sensor.