JPH0480067A - Apparatus for controlling moving speed of printing head scanning table - Google Patents

Abstract

PURPOSE:To properly control the speed of a scanning table with due regard to the factor causing the extension and contraction of a drive belt by detecting the position and speed of the scanning table to a guide rod and subjecting the movement of the scanning table to a feedback control on the basis of the detection results. CONSTITUTION:A feedback circuit 8 receives the signals outputted from the magnetic head unit 7 fixed to a scanning table 1 and constituted of magnetic heads A, B reading the magnetic signal recorded on a guide rod 21 to calculate the moving quantity and moving speed of the scanning table 1 and these moving quantity and moving speed show the moving quantity and moving speed themselves of the scanning table 1 on the guide rod 21 and receive no effect due to the extension and contraction of a drive belt 3. The feedback circuit 8 calculates the shift between the rotational speed and rotation of a stepping motor 5 and the movement of the scanning table 1 on the basis of three data, that is, the moving direction, moving speed and moving quantity of the scanning table and the pulse from a control circuit 6. Further, the feedback circuit 8 processes the calculated numerical value on the basis of the control function determined from the extension and contraction characteristics of the drive belt 3 and the objective speed and mass of the scanning table 1 to output a feedback signal to the control circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head scanning table movement speed control system in a dot impact printing apparatus.

[Conventional technology]

Conventionally, this type of print head scanning table movement speed control system, as shown in FIGS. 1
The guide rods 22 and 23 that guide the movement route of the scanning table 1
A rubber drive belt 3 is fixed to and drives the scanning table 1.
a pulley 4 that rotates to provide driving force to the drive belt 3; and a step motor 5 that rotates the pulley 4.
It is comprised of a control circuit 60 that controls the rotation of the step motor 5.

The control circuit 60 quickly accelerates the step motor 5 by sending pulses to it in response to a print command from the host controller.
The step motor 5 shifts to constant speed rotation. As the step motor 5 rotates, the pulley 4 rotates and provides driving force to the drive heald 3. As a result, the driving heald 3 pulls the scanning table 1, and the scanning table 1 moves while sliding on the guide rods 23 and 24.

The control circuit 60 controls the step motor 5 so that the scanning table 1 moves at a constant speed before reaching the printing start position. Furthermore, the control circuit 60 knows the rotation direction and rotation amount of the step motor from the number of pulses sent to the step motor 5 and the seed data.
The diameter of the pulley 4 is converted into the amount of movement of the scanning table 1 and the information is sent to the host controller.

When the host controller receives the information that the scanning table 1 has reached the printing start position, it starts sending printing information in synchronization with a printing dot clock having a constant cycle.

[Problem to be solved by the invention]

The conventional print head scanning table movement speed control method described above is
The pulse speed sent to the step motor 5 and the moving speed of the scanning table 1 are considered to be equivalent, and the control circuit 60 controls the movement of the scanning table with the pulses sent to the step motor 5.

However, the drive heald 3, which converts the rotation of the step motor 5 into movement of the scanning table 1, expands and contracts slightly when the scanning table 1 is accelerated or decelerated. For this reason, the relationship that the pulse speed sent to the step motor 5 and the moving speed of the scanning table 1 are equivalent no longer holds true.

Therefore, immediately after the step motor 5 accelerates, the scanning table 1 exhibits a speed change as shown in FIG. 9, and even after the acceleration period ends and the pulse speed sent to the step motor 5 becomes constant. The speed of the scanning table 1 is not constant.

If the relationship between the pulse speed sent to the step motor 5 and the moving speed of the scanning table 1, which is a prerequisite for control, is disrupted due to the expansion and contraction of the drive heald 3 as described above, there is a drawback that printing at an accurate position cannot be performed. .

[Means to solve the problem]

The print head scanning table moving speed control system of the present invention includes a scanning table for moving the print head, and a scanning table having a signal having a density of at least four times the printing density recorded in the axial direction of the scanning table, and the scanning table is set on a moving path. a guide rod to guide the guide, a sensor fixed to the scanning table and reading a signal recorded on the guide rod, and a means for detecting the position and speed of the scanning table with respect to the guide rod based on the signal read by the sensor. and means for feedback controlling the movement of the scanning table based on the position and speed detected by the means.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 are configuration diagrams showing one embodiment of the present invention.

In this embodiment, the guide rod 21 is replaced with a magnetic signal of 50 cycles/dragon sine wave recorded on the surface as shown in FIG. A magnetic head unit 7 consisting of a magnetic head A and a magnetic head B reads the magnetic signals read by the magnetic head unit 7, receives the signals read by the magnetic head unit 7, and compares the position of the scanning table 1 with the pulses output from the control circuit 6. The configuration includes a feedback circuit 8 that sends control information to the control circuit 6.

Next, its operation will be explained.

The control circuit 6 sends pulses to the step motor 5 to start rotation according to a print command from the host controller. As the step motor 5 rotates, the pulley 4 rotates and provides driving force to the drive belt 3.

The drive belt 3 thereby moves the scanning platform 1.

Two magnetic heads A constituting the magnetic unit 7
and B are arranged at an interval of 1/200 mm in the axial direction of the guide rod 21, as shown in FIG. 1
/200 mm corresponds to 1/4 wavelength of the sine wave of the magnetic signal recorded on the guide s21.

When the scanning table 1 starts moving, the magnetic heads A and B read signals and output signals as shown in FIG. The signal waveforms output by magnetic heads A and B are always in a relationship in which one signal is out of phase with the other signal by π'', and depending on the direction of movement of the scanning table 1, The output signal of the magnetic field leads or lags in phase by π7·'2 with respect to the pressure signal of B.

The feedback circuit 8 receives the signal output from the magnetic head unit 7 and determines the moving direction of the scanning table 1 based on the phase lag of the above-mentioned "phase lead-1". The amount and speed of movement of the scanning table 1 are calculated by counting the number of waves of the signal and detecting the speed of change of the waves.

The moving amount and moving speed of the scanning table 1 calculated by the feedback circuit 8 indicate the moving amount and moving speed of the scanning table 1 on the guide rod 21, and are not affected by the expansion and contraction of the drive belt 3. The feed pack circuit 8 calculates the rotation speed of the step motor 5, the rotation of the step motor 5, and the rotation of the moving platform 1 based on the three pieces of information, namely the moving direction, moving speed, and moving amount, and the pulses from the control circuit 6. Calculate the deviation from movement.

Furthermore, the feedback circuit 8 processes the calculated numerical value with a control function determined from the expansion and contraction characteristics of the drive heald 3, the target speed of the moving platform 1, mass, etc., and outputs a foot hack signal to the control circuit 6. The circuit is feedback time FI! A pulse corresponding to the signal from ff8 is sent to the step motor 5. As a result, the moving table quickly reaches the target speed as shown in FIG. 8, and the host controller performs printing at an appropriate printing position according to the printing information.

〔Effect of the invention〕

As explained above, the present invention does not send simple pulses to the step/motor etc., but reads magnetic signals recorded on the guide rod 21, which is a rail for moving the scanning table 1, and moves the scanning table 1. By using this information as feedback information for speed control, it is possible to appropriately control the speed of the scanning table 1 in consideration of factors such as expansion and contraction of the drive heald 3.

[Brief explanation of drawings]

1 and 2 are configuration diagrams showing one embodiment of the present invention, FIG. 3 is a diagram showing magnetic signals recorded on the guide rod 21, and FIG.
The figure shows the positional relationship between magnetic head A and magnetic head B with respect to the magnetic signal recorded on the guide rod. A diagram showing the relationship between the pulse speed and the rotation speed of the step motor in the embodiment of the invention, FIGS. 7 and 8 are block diagrams showing the conventional example, and FIG. 9 shows the pulse speed and the rotation speed of the step motor in the conventional technology. FIG. 1... Scanning table, 21, 22, 23. 24... Guide rod,
3... Drive belt, 4... Pulley, 5... Step motor, 6.60... Control circuit, 7... Magnetic head unit, 8... Feedback circuit, A, B.
...Magnetic head.

Claims (1)

[Scope of Claims] A scanning table for moving a print head; a guide rod for guiding the scanning table to a movement path, the guide rod recording a signal with a density of at least four times the printing density in the axial direction thereof; a sensor fixed to a table and reading a signal recorded on the guide rod; means for detecting the position and speed of the scanning table with respect to the guide rod based on the signal read by the sensor; A method for controlling the moving speed of a print head scanning table, comprising means for feedback controlling the movement of the scanning table based on position and speed.