JPH01241453A - Printer having printing mode switching control - Google Patents

Abstract

PURPOSE:To make a large improvement in blurring of a print, by detecting the number of simultaneously driven printing pins out of a plurality of printing pins, and by switching a first printing mode over to a second printing mode when the number of the driven printing pins which are detected satisfies a prescribed condition. CONSTITUTION:A printer has a printing head having a plurality of printing pins, a printing head driving means 4 to drive the printing head, and a printing control means 6 to supply the driving means 4 with printing data in a first printing mode wherein lap printing is not conducted or in a second printing mode wherein the lap printing is conducted. In addition, it is equipped with a driven pin number detecting means 8 to detect the number of simultaneously driven printing pins out of the printing pins in a plurality at each of successive printing positions in a line to be printed, and with a printing mode control means 10 to generate a printing mode switching signal when the detected number of the driven printing pins satisfies a prescribed condition, so as to switch the printing mode of the printer from a first printing mode to a second. In the printer, a control for switching the printing mode is conducted in response to the number of the driven printing pins which are related directly to a change in temperature of a driving coil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to print mode control in dot matrix printers such as wire dot printers.

BACKGROUND OF THE INVENTION Some conventional wire dot printers are of type 1, which have an 1-pass printing mode in which one line is printed in one pass, and a 2-pass printing mode in which one line is printed in two or more passes. Such printers are configured to switch from one-pass printing mode to two-pass printing mode when the drive voltage of the print head drops below a predetermined threshold value.

For example, in the case of a 24-pin print head, if high-density printing in which 13 or more pins are driven simultaneously continues, the drive voltage of the pin drive coil will increase as shown in Figure 7 (B). will gradually decrease.

In the conventional device, when the coil drive voltage drops by 4 volts from, for example, 40 ports, means is provided for detecting this voltage drop of 4 ports and generating a print mode switching signal.

However, such a conventional printing mode switching method has a problem in that in the 1-pass printing mode before switching to the 2-pass printing mode, there are parts where the printing becomes unclear due to printing force scratches. That is, even though the printing pressure (impact force of the pin) has decreased to the extent that it affects printing quality, there are cases in which the printer does not shift to the two-pass printing mode.

In detail, Fig. 7 shows the temporal changes in the drive current, drive voltage, and coil temperature when the printing pins are driven in M groups, and correlates them with each other. Let me show you. When high-density printing continues, where 13 or more pins are simultaneously driven, the drive voltage gradually decreases as shown in Figure 7 ('B), and at the same time the coil temperature rises as shown in Figure 7 (C). The resistance of the coil increases), and the peak of the drive current gradually becomes lower as shown in FIG. 7(A). On the other hand, when low-density printing continues, the drive voltage hardly decreases as shown in FIG. 7(B), and the drive current and coil temperature (not shown in FIG. 7) do not change much.

However, in high-density printing, when the coil temperature rises to a certain extent, the drive voltage does not drop much (towards the dashed line during low-density printing) even though the drive current decreases due to the increase in coil resistance. (shift), the threshold value for switching the print mode cannot be reached. Furthermore, as the coil temperature rises, the time it takes for the temperature to remain below the threshold value increases, and as a result of the low printing pressure due to the reduction in drive current, the printing force streak portion becomes longer.

Further, the change in coil temperature over time is shown as a predicted diagram in FIG. 7(C). In reality, it is difficult to detect coil temperature changes at such high frequencies.

This is because conventional temperature sensors do not have frequency characteristics sufficient to detect such temperature changes.

Therefore, it is difficult to accurately switch the printing mode by detecting the coil temperature.

Therefore, it is an object of the present invention to provide a printer with more accurate print mode switching.

Means for Solving the Problems In order to achieve the above object, the present invention provides a system in which the temperature change of the drive coil of the print head increases the number of driving printing pins at each printing position as well as the number of driving printing pins at successive printing positions. Focus on patterns of change and things related to.

Therefore, according to the present invention, as shown in the basic configuration diagram of FIG.
, a print head driving means 4 for driving the print head, and a print control for supplying print data to the driving means 4 in a first printing mode in which overlapping printing is not performed or in a second printing mode in which overlapping printing is performed. means 6, further comprising drive pin number detection means 8 for detecting the number of simultaneously driven printing pins among the plurality of printing pins at each successive printing position of a line to be printed; When the detected number of driven printing pins at the position satisfies a predetermined condition, a printing mode switching signal is generated to switch the printing mode of the printer from the first printing mode to the second printing mode. A mode control means 10 is provided.

In the printer of the present invention, which has a configuration more than the function, in response to the number of drive printing pins directly related to the temperature change of the drive coil,
It acts to control printing mode switching.

EXAMPLES Next, examples of the present invention will be described in detail below.

FIG. 2 is a block diagram showing a print head control section of a wire dot printer according to the present invention. In this embodiment, the print head 20 has 24 pins and 1 pin, as shown in FIG. 2A.
Two rows of two pins each are arranged vertically offset from each other, thus row 1 consisting of odd numbered pins l, 3, . . . 23 and row 2 consisting of even numbered pins 2.4, . . . 24. It consists of.

A control unit that drives and controls the printing pad 20 is a first
Corresponding to the figure, a print head drive section 40, a print control section 60
, drive pin number detection unit 80, and print mode control unit 100
It is equipped with.

In this embodiment, the drive pin number detection section 80 is connected to the print head drive section 40 and detects the number of drive printing pins from the drive current flowing through the drive coil of each printing pin.
This is shown in detail in FIG.

This detection unit 80 detects that when the number of drive printing pins≧(k is an integer less than or equal to the maximum number of pins, for example, −13), Px=
It generates an output of 5 volts, Py-5 volts, and on the other hand, when the number of drive printing pins <k, Px=5 or 0 volts, Py-
It produces an output of 0 volts (details are further explained in FIG. 3).

Print mode control unit 1 connected to receive this output
00 generates a print mode switching signal to the print control section 60 when the number of driven print pins satisfies a predetermined condition. In this embodiment, the predetermined condition is that the number N of high-density (or first type) printing positions, which is greater than or equal to the number of driving printing pins, is equal to or greater than the number of driving printing pins after the first high-density printing position. A predetermined first number n (n is an integer) is reached before the number M of low-density (or second type) printing positions that is less than or equal to a predetermined second number m (m is an integer). It is a condition.

Here, the first number n and the second number m will be explained. The number n is the number of printing positions from the start of high-density printing until just before the printing becomes unacceptably blurred due to a drop in drive voltage and an increase in coil temperature. On the other hand, the number m is the number of printing positions until the drive voltage returns to a normal value when low-density printing is performed immediately after the high-density printing position reaches n-1. These numbers n and m depend on the power supply capacity, the heat dissipation characteristics of the print head, and the like.

In order to determine whether or not the above conditions exist, the print mode control unit 10
0 includes a counter control section 102, a counter N, and a counter M. The counter control tl=lO2 generates a first count control signal when the output of the detection unit 80 indicates that the number is greater than or equal to the number of driven printing pins, and generates a second count control signal when it indicates that the output is less than k. generates a count control signal. In response to the lth count control signal, a counter N counts up to count the number of high-density print positions, and when the counter N reaches a first number n (e.g. n-6) , generates a print mode switching signal.

The counter M responsive to the second count control signal is
To count the number of low-density print positions that occur after the first high-density print position, the counting operation is disabled while counter N is zero, and when counter N is non-zero, a second count control signal is activated. Count up in response.

When this counter M reaches a second number m (for example m-3), it resets and at the same time clears the first counter.

In this embodiment, the print control section 60 and the print mode control section 100 are realized by the CPU 120 having a memory storing a control program.

Further, in FIG. 2, other printer parts such as a carriage are omitted because they are not directly related to the present invention.

Next, the drive pin number detection section 80 will be explained with reference to FIG. Note that this figure also shows a detailed circuit of a part of the print head drive section 40.

First of all, the print head drive unit 40 includes, for each of the pins 1 to 24, drive coils L1 to L24 connected to a drive voltage VD (-40 volts), and drive transistors (with collectors connected to these coils, respectively). Trdl=
Trd24). Each collector is connected to the diode D1 through the common connection point 42 through the detection resistors (Rsl to R524) of the drive pin number detection section 80. The detection unit 80 includes a detection transistor Trs whose pace is connected to the anode of a diode D1, and resistors R1 and R2 are connected between the emitter of this transistor and ground. The junctions of these resistors are connected to the inverting inputs of two comparators C1 and C2; the non-inverting inputs of these comparators are connected to the voltage divider Rfl
The reference voltage v refl (e.g., 3,34 ports) defined by ~Rf3 and v ref2 (e.g., 2
．． 62 volts).

The outputs of these comparators C1 and C2 are the aforementioned Px.

It is Py.

Regarding the operation of the detection unit 80, the drive transistor Trdl
When is turned on, coil drive current i1 flows and at the same time current 12 flows through resistor Ro, diode D1 and resistor 1Rsl as shown. As this current 12 flows, the pace voltage vi of Trs decreases, the pace current ib decreases, and the current ics flowing between C and E of Trs decreases, so that the output voltage vo decreases. Here, since the detection resistors Rsl to Rs24 all have the same value, the detection current is flowing through all the drive transistors becomes equal.

Therefore, the current flowing into the diode DI increases in proportion to the number of driven pins, the ib of Trs decreases in proportion to the number of pins, and finally the output voltage vo increases in proportion to the number of pins. Decrease.

This output voltage vo is converted into a reference voltage v refl and v r
By comparing with ef2, the outputs Px and Py of comparators CI and C2 become Px=OV when O≦number of pins≦x−1.
S Py=OV, and when X≦number of pins≦y-1, Px
=5V1Py=OV, and when y≦number of pins, P
x=5V, py-sv (e.g., reference voltage v r
efl = 3.34 volts, reference voltage v reH = 2
．． 62 volts, X=9, y-13). Now, if y-k (for example, k-13),
Only when the number of printing pins≧, both Px and Py are 5 volts.

Next, the printing control operation executed by the CPU 120 in FIG. 2 will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a 70-chart showing the entire printing flow for printing one line. In the first step 200, a one-pass printing process, the carriage is moved to one printing position, where printing is performed according to printing data. In the next step 202, it is checked whether the print data is finished, and if YES, this flow ends. If NO, the next step 204 checks whether there is a 2-pass request. If NO, the process returns to step 200 and prints at the next print position. If YES in step 204, that is, the two-pass printing mode is requested, a two-pass printing process is executed in step 206, and the remaining portion of the line being printed is printed in two passes. Next, in step 208, it is checked whether or not the print data has ended. If NO, the process returns to step 206; if YES, this flow ends.

It is the print mode control flow of FIG. 5 that sets the two-pass request tested in step 204 above, and this flow is executed in step 200 of FIG.

In the first step 210 in FIG. 5, print data for one print position is set in the print head drive unit 40.

In the next step 212, pin number data (Px, Py) is loaded from the detection unit 80.

The next decision step 214 tests whether the number of pins≧k by checking whether Px-high and PY-high. If YES, that is, when indicating a high-density printing position, for example, as shown in FIG. 6 (in this figure, the two rows of pins 1 to 24 shown in FIG. Print position 1.2.3.4.6
．． 7, clear the counter M in step 216;
At step 218, 1 is added to the counter N. Then, in step 220, the counter N=n (in FIG. 6, n-6
), and if NO, this flow ends. On the other hand, if YES, for example, in the case of printing position 7 in FIG.
Set path request and exit.

On the other hand, if the answer in step 214 is NO, that is, in the case of a low-density printing position, a check is made in decision step 224 to see if the counter is N-0. If YES, that is, if the first high-density printing position has not occurred, the process ends. If NO, for example, in the case of print position 5, 1 is added to the counter M in step 226, and it is checked in step 228 whether the counter M=m (m=3 in the example of FIG. 6).

If no, the process ends. If YES, step 230
Then, counters N and M are cleared and the process ends.

Next, a second embodiment of the present invention will be described.

In the above embodiment, the drive pin number detection unit 80 as shown in FIGS. 2 and 3 was provided to detect the number of drive printing pins.
This detection section 80 can be configured to directly receive print data from the print control section 60 shown in FIG. 2, and send a signal representing the number of drive pins to the counter control section 102. In this case, the counter control section 102 includes a section that compares the number of drive pins with k.

Such a detection unit 80 can be easily implemented by the CPU 120.

As a third embodiment, the two counters N and M in FIG. 2 can be configured with one up/down counter. In that case, the counter may be configured to count up by a predetermined increment amount in response to the first counter control signal and to count down by a predetermined increment amount in response to the second counter control signal.

In that case, a print mode switching signal can be generated when the up/down counter reaches a predetermined count value. The modifications to the flow of FIG. 5 necessary to implement such an up-down counter will be apparent to those skilled in the art.

As a fourth embodiment, in order to perform more precise control, it is also possible to provide two or more different predetermined values k to divide the position into high-density printing positions, medium-density printing positions, and low-density printing positions. At that time, in Figure 2, the number of counters is increased, and
The amount of increment or decrement in the up-down counter in the third embodiment may be adjusted as appropriate.

Effects According to the present invention, which has been described in detail above, it is possible to change the printing mode more accurately than in the past, and it is possible to significantly improve printing force deviation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a printer having print mode control according to the present invention. FIG. 2 is a block diagram showing one embodiment of the printer of the present invention. FIG. 2A is a diagram showing an offset arrangement of two rows of print pins of a print head. FIG. 3 is a circuit diagram showing a detailed circuit of a part of the print head drive section and the drive pin number detection section of FIG. 2; FIG. 4 is a 70-chart showing printing 70- executed by the CPU of FIG. FIG. 5 is a flowchart showing a print mode control flow executed by the CPU of FIG. FIG. 6 shows the driving printing pins at each printing position used to explain the present invention in detail, and two rows of printing pins are shown in one row to simplify the explanation. FIG. 7 shows changes in the drive current, drive voltage, and coil temperature of the print pin drive coil in relation to each other when the print pins of the print head are continuously driven at high density. [Description of symbols] 2.20: Print head, 4: Print head drive means, 6: Print control means, 8: Drive pin number detection means, 10: Print mode control means, 40: Print head drive section, 60: Print control 80: Drive pin number detection section, 100: Print mode control section, 102: Counter control section.

Claims (5)

[Claims] (1) It has a print head with multiple print pins, and has a first print mode in which one line is printed in one pass, and a second print mode in which one line is printed in two or more passes. In the printer, a) a detection means for detecting the number of printing pins that are simultaneously driven among the plurality of printing pins at each successive printing position of a line to be printed, and b) this detected driving at each printing position. Printing mode control means for generating a printing mode switching signal for switching the printing mode of the printer from the first printing mode to the second printing mode when the number of printing pins satisfies a predetermined condition; Includes printer. (2) In the printer according to claim 1, the predetermined condition is that the number (N) of printing positions of the first type in which the number of detection drive printing pins is equal to or more than a predetermined number (k) is After the printing position, the number of detection drive printing pins reaches a predetermined number (k
), the condition is that the number (M) of the second type printing positions, which is less than ), reaches a predetermined first number (n) before reaching a predetermined second number (m). printer. (3) In the printer according to claim 2, the printing mode control means: (a) responds to the number of detection drive printing pins from the detection means to ensure that the number of detection drive printing pins is equal to or greater than the predetermined number; a counter control means for generating a first count control signal when the count is less than the predetermined number, and generating a second count control signal when the count is less than the predetermined number;
a first counter (N) for counting the number of printing positions of the type, the first counter generating the printing mode switching signal when the first counter reaches the first number (n); , c) a second counter (M) for counting the number of printing positions of the second type that occur after the printing positions of the first type in response to the second count control signal, A printer characterized in that the second counter is reset when the second number (m) is reached, and the printer comprises resetting the first counter. (4) The printer according to claim 1, further comprising print head driving means to which print data is supplied to drive the print head, and wherein the detecting means detects the print data supplied to the print head driving means. Detecting the number of driven printing pins from the printer. (5) The printer according to claim 1, further comprising print head driving means for driving a plurality of coils for respectively operating the plurality of printing pins of the print head, and the detection means includes a plurality of coils for driving the plurality of printing pins of the print head. Detecting the number of driving printing pins from the current flowing through the printer.