JP4163901B2 - Control method of electromagnetic dot marking device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling a dot marking device having a solenoid valve-type opening / closing mechanism using a solenoid coil, and more particularly to controlling a dot marking device that prints on an object under conditions where the printing interval fluctuates so that the printing speed is accelerated or decelerated. Regarding the method.
[0002]
[Prior art]
A dot marking device using paint is widely used for product printing indicating materials, standards, etc., management printing for managing products in a factory, and the like.
[0003]
An example of a so-called solenoid type dot printing apparatus provided with an electromagnetic valve type opening / closing mechanism is described in JP-A-2-131164. In such a printing gun for a dot printing device, the valve is opened and closed by attracting the movable iron core connected to the valve body by the electromagnetic force generated by energizing the solenoid coil to open the valve and return by the action of the spring. To close the valve. When the valve is opened, pressurized liquid paint is discharged from the valve opening, and dots are printed on the object.
[0004]
FIG. 1 shows an example of a simplified sectional view of a marking head of a solenoid type dot printing apparatus. The marking head includes a hollow solenoid bobbin 3 having a solenoid coil 4 on the outer periphery, a fixed iron core 2 fitted in a liquid-tight manner on the inner wall of the solenoid bobbin 3 in a part of the hollow of the solenoid bobbin 3, a solenoid The movable iron core 1 is arranged in the hollow of the bobbin 3 so as to keep a gap with the inner wall of the solenoid bobbin 3, and has one end face facing one end face of the fixed iron core 2 and keeping a gap. And a tip 1a extending from the other end surface of the movable iron core 1, and a main body 5 including a valve seat 5a that engages with the tip of the tip 1a and fixing the nozzle 6. . The paint can be supplied from the vicinity of the nozzle 6.
[0005]
When printing is performed using such a solenoid type marking head, a print timing signal serving as a trigger for starting energization of the solenoid coil is used. The generation of the print timing signal may be internal synchronization or external synchronization.
[0006]
In the case of internal synchronization, a discharge interval for continuously discharging dots is set in advance, and a print timing signal is output at each set time. In this case, print timing signals are output at regular intervals.
[0007]
On the other hand, in the case of external synchronization, a signal coming from the outside is counted, and a print timing signal is generated when the signal is input a set number of times. In this case, when the signal from the outside is indeterminate, the print timing signal is not output at equal intervals.
[0008]
When the control unit of the dot marking device determines that dots are ejected at a certain printing timing, the solenoid coil is energized for the time specified by the energization time setting value using the printing timing signal as a trigger.
[0009]
When printing is performed, for example, when printing dots at a high frequency of 1 kHz or more, and when printing dots at a low frequency of 100 Hz or less, the optimum value of the time for energizing the solenoid coil is different.
[0010]
The energizing time set based on the low frequency is too long as the energizing time required at the high frequency, so problems such as excessively large dots and unstable valve opening / closing occur. The valve will not close. On the other hand, the energization time set based on the high frequency is too short compared to the energization time required at the low frequency, causing problems such as the valve not opening. Therefore, it is difficult to make the dot diameters uniform when the frequency changes greatly as in the case of printing while accelerating from the stopped state to the high speed state.
[0011]
When high-speed printing is performed from a printing stopped state, it is necessary to increase the energization time of the solenoid coil in order to properly discharge the first dot. At this time, if the energization time for the first dot is increased by adding a correction time, the time from the end of energization to the start of the next energization (hereinafter referred to as “rest time”) is shortened. The printing device controls dot discharge by opening and closing the valve. However, especially during high-speed printing, the pause time is originally short, so the time required to close the valve cannot be ensured by correction, and dots are connected or large. There were problems such as becoming.
[0012]
In a solenoid valve type printing apparatus using a solenoid coil, an energizing force (attraction force) by an electromagnetic force is applied to a magnetic body (movable iron core) in the solenoid by energizing the solenoid coil to open the valve. As the energization of the solenoid coil is started and the current increases, the thrust increases and the valve opens. When the energization is stopped, the thrust decreases and the valve is closed by the action of the return spring. When energization is stopped, energy remains in the solenoid coil, and it takes time to dissipate this residual energy.
[0013]
If the dot-to-dot printing interval is longer than the time it takes for the energy remaining in the solenoid coil to disappear, the next time the solenoid coil is energized, there is no energy accumulation in the solenoid coil, so the first energization As with time, the current increases and the valve opens at the same time. However, if the dot printing interval is shorter than the time required for the energy remaining in the solenoid coil to disappear, energy will remain in the solenoid coil for the next energization time after the end of the first energization. The thrust is sufficient to open the valve in a shorter time than sometimes. Therefore, when the energization time is constant regardless of the dot interval and the dot printing interval is shorter than the time required for the solenoid coil to have no residual energy, the remaining energy of the valve remains. As a result, the paint discharge amount increases and the dot diameter increases.
[0014]
[Problems to be solved by the invention]
The present invention has been made to solve the above problems, and provides a method for controlling a solenoid type dot printing apparatus that performs stable printing with a uniform dot diameter even when the printing speed is accelerated or decelerated. Is.
[0015]
[Means for Solving the Problems]
Normally, the solenoid coil energization time is set according to the print timing generated by the internal clock in the print head controller or the print timing determined by the signal from the encoder, etc. This setting value is never changed. However, the apparatus of the present invention performs stable printing with uniform dot diameters even when the printing speed is accelerated or decelerated by changing and correcting the set energization time during printing according to the state of the drive pulse generation. is there.
[0016]
Hereinafter, embodiments of the present invention according to the generation method of the print timing signal will be described.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment of the present invention, for example, when a print timing signal is generated at a set fixed time by an internal clock, an appropriate number corresponding to the print timing signal generation (hereinafter referred to as “timing count”), The number of times the drive pulse was turned off when the timing was generated (hereinafter referred to as “dot pause number”) between the time when the timing signal is generated and the solenoid coil drive pulse is turned on until the next drive pulse is turned on. ) Is used to calculate the current dot interval, and the energization time of the solenoid coil is changed and corrected according to the calculated value.
[0018]
When the timing is obtained from an input signal from the outside (encoder synchronization or the like), the generation of the timing signal is not constant because the input signal from the outside is not at regular intervals. Therefore, the timing generation time is measured by counting the intervals at which the timing signals are generated with the internal clock. The number of dot pauses is the same as that when the print timing is generated by the internal clock.
[0019]
FIG. 2 is a timing chart showing the relationship among printing timing, energization time setting value, correction value, and driving pulse for driving the solenoid coil according to the method of the present invention. When the print timing signal is generated, energization of the solenoid coil is started. The energization time set value is a time for energizing the solenoid coil that is set according to the printing timing. If there is no correction value, the solenoid coil is energized for the time specified by the set value.
[0020]
The energization time of the solenoid coil is changed by referring to a list in which the number of times and the correction value of the energization time corresponding to the number of dot pauses are described. Since the correction value varies depending on the print head to be used or the like, an optimum value is obtained while actually ejecting dots according to the use conditions, and a correction value table is created and stored in the print head control device.
[0021]
When the print head control device determines that dots are ejected at a certain print timing, if there is a correction value, the energization time is changed by delaying the start of energization of the solenoid coil by the time set by the correction value. Since the energization is started after the correction time set with this correction value has elapsed after the printing timing signal has been generated, the correction time is subtracted from the energization time setting value for the time that the solenoid coil is energized (width of drive pulse current). (FIG. 2). In the correction, the energization time is set longer than the required energization time, and the correction is performed by subtracting the correction value from the set value. By delaying the actual energization start by the correction time from the energization start timing, it is possible to change the energization time while keeping the rest time constant (FIG. 3B).
[0022]
In addition, the energization time of the solenoid coil can be reduced without changing the energization start timing (FIG. 3A), but in that case, the pause time varies.
[0023]
【Example】
A desired dot pattern as shown in FIG. 4 is created, and the optimum value of the actual solenoid coil energization time necessary to obtain a substantially constant dot diameter with respect to each dot interval is actually measured, and the correction value corresponding thereto is measured. A table is created (FIG. 5).
In the correction value table shown in FIG. 5, N represents the number of driving pulse pauses. The count value t is determined as follows.
Count value t for external synchronization
When a print timing signal is generated when one signal is input from the external encoder to the print head controller, the number of clocks between the external input signals is set to a count value t. For example, in the case shown in FIG. 6, since the number of clocks between two external input signals is 7, the count value t is 7.
Count value t for internal synchronization
In the case of internal synchronization, the print timing signal interval (hereinafter referred to as “dot interval”) is set in units of time. Therefore, the count value t is obtained by dividing the dot interval by the time interval (cycle) of the clock. For example, when the clock frequency is 10 kHz and the dot interval is 0.1 ms, the count value t is t = 0.1 ms / 0.1 ms = 1.
FIG. 7B shows a result of actual dot printing according to the present invention. FIG. 7A shows a case where correction is not performed, but it can be seen that the dot diameter increases as the dot interval decreases. Here, in both FIGS. 7A and 7B, the dot interval is set to 2 msec. Under the conditions of this embodiment, even when the number of pauses is 0 and 5 times, the dot diameter differs only by a few millimeters of comma, but this difference becomes large because when dots are drawn, the dots are overlaid. End up.
FIG. 8 is an example of a print head control apparatus 10 that implements the present invention by internal synchronization. The correction value table (FIG. 5) created as described above is stored in the correction table memory 15. The control timer 13 has a built-in clock generator and generates a required print timing signal. The CPU 14 calculates a count value t from the print timing signal and the clock signal, and obtains a correction time by referring to the correction value table based on the result. The counting circuit 12 triggers the solenoid coil drive 11 after a correction time from the solenoid coil energization setting value, and generates a drive pulse current for driving the solenoid coil 20 in the solenoid coil drive.
FIG. 9 is an example of a print head control device 18 that implements the present invention by external synchronization. Except for having an external signal counting circuit 16 and an external counting timer 17, it has the same components as in FIG.
[0024]
【The invention's effect】
In the present invention, a stable dot pattern is obtained by previously setting an energization time corresponding to the dot interval in the printing apparatus. According to the present invention, dots having the same diameter can be printed even if the dot ejection cycle changes during printing. In addition, when performing high-speed printing from the printing stopped state, the printing is improved from the stopped state.
[0025]
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an example of a marking head controlled by the method of the present invention.
FIG. 2 is a timing chart showing the relationship among print timing, energization time set value, correction value, and drive pulse according to the method of the present invention.
FIG. 3 is a timing chart showing the relationship between printing start timing and solenoid coil drive pulses according to the present invention.
FIG. 4 is a diagram showing predetermined dot patterns with various dot intervals.
FIG. 5 is a correction value table created based on the dot pattern shown in FIG.
FIG. 6 is a timing chart showing an example of the relationship between external timing and a clock.
7A is a dot pattern when printing is performed without using correction values, and FIG. 7B is a dot pattern when printing is performed using correction values.
FIG. 8 is a control circuit of an embodiment of the present invention using an internal clock.
FIG. 9 is a control circuit of an embodiment of the present invention based on external timing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Movable iron core 1a Tip of movable iron core 2 Fixed iron core 3 Solenoid coil bobbin 4 Solenoid coil 5 Main body 5a which fixes the valve Valve 6 Marking head nozzle 10 Internal synchronization control circuit 11 Solenoid driver 12 Counting circuit 13 Control timer 14 CPU
15 Correction value table memory 16 External signal counting circuit 17 External signal counting timer 18 External synchronization control circuit 20 Solenoid 21 External signal generator

Claims (2)

A printing control method for a solenoid valve type print marking device using a solenoid coil, wherein a solenoid coil energization time is set in response to a print timing signal at a predetermined interval, and correction corresponding to each different dot interval for the print marking device. A correction value table made up of values is prepared in advance, the dot interval at the time of printing is measured with a clock, and the dot is based on the correction table so that the dot has a substantially constant diameter corresponding to the measured dot interval. Correcting the set energization time of the solenoid coil and correcting the set energization time delays the start of the solenoid coil energization time by a correction time determined by a value in the correction value table. Printing control method for valve-type printing marking device. Enough to be faster printing, in short dot interval, changing the value of the correction value table, the print control method of an electromagnetic valve type printing marking device according to claim 1.

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