JPH0436950Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an XY plotter in which a writing block is moved by a pulse motor via drive force transmission means such as gears and wires.

(Prior art) Conventionally, in an XY plotter, by driving a step motor, this driving force is transmitted to and from a writing block through gears, wires, etc., and the writing block is moved to create a plot. When the step motor is switched from forward rotation to reverse rotation, some of the step number writing blocks will not move during forward movement.
A situation occurs in which the writing block does not return to its normal position. Incidentally, this occurs due to backlash occurring in the gears and wires for transmitting the driving force from the step motor to the writing block. That is, when gears are used as the driving force transmission means, a narrow gap is formed between the engaged gears during reverse rotation, resulting in a backlash. On the other hand, when wire is used as a driving force transmission means, if there is slack in the wire,
Due to this slack, when the step motor is switched from normal rotation to reverse rotation, the wire does not move for some time even though the step motor has started driving, which causes backlash.

To solve this problem, in conventional XY plotters, when gears were used as a power transmission means, the depth of engagement between the gears was adjusted mechanically by making it deeper or shallower. On the other hand, when a wire is used as the driving force transmission means, the tension is successively measured and adjusted using a tension gauge.

(Problem to be solved by the invention) However, in such a conventional XY plotter using a step motor, the backlash of gears and wires, which are the driving force transmission means, was mechanically removed, making adjustment work difficult. This method is troublesome and time-consuming, and additional equipment must be added to eliminate the effects of backlash, resulting in high costs. Even if it is assembled without buckling, buckling will occur due to gear wear and wire slack due to aging, and for example, dirt may adhere to the meshing part of the gears, resulting in poor meshing. To prevent this, adjustments must be made again.
A problem arises in that maintenance becomes complicated.

Therefore, the present invention was devised to solve the above-mentioned problems of the conventional example.The purpose of this invention is to eliminate the backlash electrically, eliminate the need for troublesome adjustment work, and reduce costs. To provide an XY plotter which can accurately return a writing block to a regular position during backward movement.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an XY plotter in which a writing block is moved in the X and Y directions by a pulse motor via a driving force transmission means. A detector for detecting the position of the writing block, and a detector for reciprocating the writing block starting from the home position by rotating the pulse motor in the forward and reverse directions at the time of reset, and a detector for detecting the position of the writing block when the writing block moves forward from the home position to the turning point. The difference between the step of the pulse motor and the step of the pulse motor when it moves back from the turning point to the home position is set as a backlash correction value of the driving force transmission means, and the correction value is used when the pulse motor is driven in reverse during printing. and a control means for controlling the addition to the drive pulse when driving.

(Function) In the present invention having the above configuration, at the time of reset, the control means rotates the pulse motor in forward and reverse directions to generate driving force. This driving force is transmitted to the writing block via the driving force transmission means, and the writing block reciprocates from a fixed position as a starting point. While the position of this reciprocating writing block is detected by a detector, the control means controls the step of the pulse motor when the writing block moves forward from the normal position to the turning point, and the step of the pulse motor when the writing block moves backward from the turning point to the normal position. By setting the difference from the step of the pulse motor at the time as the backlash correction value of the driving force transmitting means, and adding the correction value to the drive pulse when the pulse motor is driven in reverse during drawing, backlash can be removed. It is something to do.

(Example) The present invention will be explained below based on the illustrated example. Fig. 4 shows an automatic drawing machine to which the XY plotter according to the present invention is applied.
have. X rails 3 and 4 are laid on both ends of this mounting table 2.
X cursors 5 and 6 are movably attached to the cursors 5 and 6. Both ends of a Y rail 7 are fixed to the X cursors 5 and 6, and a Y cursor 9 having a drawing head 8 as a writing block is movably attached to the Y rail 7. The X cursors 5 and 6 and the Y cursor 9 are moved by driving a step (pulse) motor (not shown) to feed out or wind in a wire serving as a driving force transmission means, that is, to move the drawing head based on the drawing information. A drawing is created on a paper (not shown) placed on the mounting table 2 by moving the paper 8 according to a desired shape.

FIG. 1 is a block diagram showing the control system of this embodiment, and in the figure, 10 is a detector (sensor).
For example, a sensor without hysteresis, such as an optical sensor or a magnetic sensor, is used and is fixedly disposed within the movement range of the drawing head 8. Further, if the sensor 10 detects the drawing head 8 as close as possible, good detection accuracy can be obtained. 11
12 is a correction register, which controls the step motor 1 at the time of reset.
3 is moved back and forth and the difference in steps is stored. 14 is an output counter that waits for the number of movement steps from the control circuit 11. 15 is an adder,
A direction control circuit 16 controls the direction of the drawing head 8 when a drawing command is sent from the input device 17;
8 rotates the step motor 13 in the reverse direction to move the drawing head 8
19 is a drive circuit for controlling the step motor 13; 20 is a reversal determination circuit that determines whether the motor has moved in a direction different from the current direction and outputs a signal 0 when the motor rotates in the normal direction and a signal 1 when the motor rotates in the reverse direction (in a different direction); This is an AND circuit for outputting the logical product of the step number stored in the correction register 12 and the signal of the inversion determination circuit 18 to the adder 15.

In the above configuration, in this embodiment, the backlash of the driving force transmission means is eliminated as follows. That is, FIG. 2a is a flowchart showing the backlash step detection operation when the sensor 10 is detected at the time of reset, and FIG. 3 is an explanatory diagram of the operation. The step motor 13 is rotated until it reaches a fixed position (A shown in FIG. 3), and the step motor 13 is further rotated n steps in the same direction so that the drawing head 8 moves to the turning point (FIG. 3 B). ). Then, in step N, the step motor 13 is rotated in the opposite direction to move the drawing head 8 (FIG. 3C). This n step is the number of steps stored in the output counter 14. Here, if there is a backlash in the wire as a driving force transmission means, the drawing head 8
Since the detected position of 0 has not been reached, the step motor 13 is rotated one step at a time, and the number of steps sent until the sensor 10 turns OFF is the backlash amount. That is, in step N = 0 is set as the backlash step, and then in step it is determined whether the sensor 10 has changed from ON to OFF, and if it is ON, it is set to 1 in step N.
The step motor 13 is rotated step by step until the sensor 10 turns OFF, and this number of steps N (D shown in FIG. 3) is the backlash step, which is stored in the correction register 12 and the process ends.

Next, the operation during drawing will be explained based on the flowchart shown in FIG. 2b. First, the input device 17
When it receives a drawing command, it sends a command to move by the number of output steps to the output counter 14 via the control circuit 11 (step), and then in step, the reversal discrimination circuit 18 controls the step motor 13.
It is determined whether the rotation is normal or reverse, and if the rotation is normal, there is no backlash problem, so the output is performed as is in steps. When inverting in a step, the value stored in the correction register 12 is added to the actual output by the adder 15 (step) and output. That is, the number of output steps
By adding the steps and outputting the result, the backlash at the time of inversion is removed.

In this way, the amount of forward movement and the amount of backward movement of the drawing head 8 during drawing can be matched. Therefore, the plotting head 8
can be returned to its normal position with high precision, allowing accurate drawing to be achieved.

Therefore, in the above embodiment, when resetting, the step motor 13 is rotated an extra n steps from the position where the drawing head 8 is detected by the sensor 10, the motor 13 is reversed for the n steps, and then the sensor 13 is rotated again after the n steps. When the detected position appears, that is, the back-and-forth step difference N is set as a back-crash correction value, and when the step motor 13 is driven in reverse, the back-crash correction value N is added to the drive pulse.

Incidentally, in the above embodiment, a case was explained in which a wire was used as the driving force transmission means, but it goes without saying that the present invention can also be applied to a gear or the like.

(Effects of the invention) The XY plotter according to the invention has the above-mentioned structure and function, and can electrically eliminate the bumps occurring in the driving force transmission means and their secular fluctuations, thereby eliminating the need for troublesome mechanical This eliminates the need for extensive adjustment work, and also eliminates the need to add extra equipment to eliminate backlash, resulting in an effect that costs can be reduced.

Furthermore, the amount of forward movement and the amount of backward movement of the writing block during drawing can be matched. Therefore, the writing block can be returned to its normal position with high accuracy, and accurate drawing can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control system in an embodiment of an XY plotter according to the present invention, FIGS. FIG. 4 is a plan view showing an automatic drawing machine to which the same embodiment is applied. Explanation of symbols, 8... Drawing head (writing block), 10... Sensor (detector), 11... Control circuit (control means), 12... Correction register, 13...
...Step motor (pulse motor), 14...Output counter, 15...Adder, 16...Direction control circuit, 17...Input device, 18...Reversal discrimination circuit.

Claims (1)

[Scope of utility model registration request] An XY plotter in which a writing block is moved in the X and Y directions by a pulse motor via a driving force transmission means, includes a detector for detecting the position of the writing block, and a detector for detecting the position of the writing block, and a detector for moving the writing block by rotating the pulse motor in forward and reverse directions at the time of reset. The writing block is moved back and forth from a fixed position as a starting point, and the difference between the step of the pulse motor when the writing block moves forward from the fixed position to the turning point and the step of the pulse motor when it moves backward from the turning point to the fixed position is calculated. An XY plotter characterized in that the XY plotter is provided with a control means for performing control to set a backlash correction value for the driving force transmission means and to add the correction value to a drive pulse when the pulse motor is driven in reverse during plotting.