JPH08267793A - Dot impact printer - Google Patents

Abstract

PURPOSE: To provide a dot impact printer in which the throughput of the printer is so improved as to print at a printing speed responsive to the output voltage of a secondary side power source for supplying power to a printing mechanism. CONSTITUTION: This dot impact printer comprises a ROM 11 for storing a table in which the voltage zone of the input side voltage of the switching circuit of a power source 6 is corresponded to the printing speed, and a CPU 7 inputting the input side voltage V1 of the switching circuit to output a control signal responsive to the printing speed to an I/O driver 10 by selecting the speed from the ROM 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot impact printer having a switching circuit on the secondary side of a power supply circuit for supplying electric power to a drive circuit of a printing mechanism section.

[0002]

2. Description of the Related Art Conventionally, dot impact printers have been made compact, and a power supply circuit for supplying electric power to a printing mechanism portion such as a print head, a spacing motor, a line feed motor, etc. has been advanced in the compact direction. I'm out. The dot impact printer has a switching circuit on the secondary side of the power supply circuit, supplies the output of the switching circuit to the I / O driver of the printing mechanism section, and controls the drive current by the control signal of the control section to control the space. -Some machines control the printing speed by rotating the single motor.

As shown in FIG. 8, the load characteristic of the voltage and the current of the switching circuit is such that the voltage drops linearly with the increase of the current accompanying the increase of the power consumption on the input side of the switching circuit. At the output side of the switching circuit, a constant voltage is maintained up to a predetermined current value.

By the way, the control unit monitors the output side voltage of the secondary side switching circuit. When the voltage is equal to or higher than the constant voltage value, printing is performed at a normal specified printing speed. -The rotation speed of the solid printing is reduced and printing is performed at the solid printing printing speed (for example, 50% of the specified printing speed).
This is because when the number of print dots increases like a graphic, the power consumption in the print head increases, and when printing continues at the specified print speed, the output side voltage falls below the voltage value Vs, and the impact of print dots due to insufficient power. This is because the force may be weakened and the printed characters may fade, and even if the printing speed is reduced at that point, it will be too late.

[0005]

In the conventional dot impact printer, the control unit judges whether the output side voltage is equal to or higher than the constant voltage value or lower than the normal specified printing speed.
Alternatively, since the printing is performed at the solid printing speed, there is a problem that the output of the printer is lowered.

The present invention detects a voltage that changes according to the power consumed in the printing mechanism, and prints at a printing speed corresponding to the voltage so as to maintain a sufficient impact force and rapidly increase the printing speed. It is an object of the present invention to provide a dot impact printer in which the output of the printer is improved so as not to drop it.

[0007]

In order to achieve the above object, in the dot impact printer of the present invention, the input side voltage of the switching circuit that drops linearly in response to an increase in the drive current supplied to the printing mechanism section A table storage means for storing a table in which a voltage band and a printing speed are associated with each other, an analog / digital conversion means for inputting a voltage on an input side of a switching circuit and converting it into a digital value, and an analog / digital conversion means. And a print speed selection means for selecting a print speed from the table storage means and outputting a control signal corresponding to the print speed to the I / O driver.

Further, in order to achieve the same object, in the dot impact printer of the present invention, the output of the analog / digital converting means is further inputted to obtain a predetermined expected voltage after t seconds from the load voltage characteristic formula. Estimated voltage calculation means for outputting to the printing speed selection means.

[0009]

When the input side voltage of the switching circuit is input to the analog / digital conversion means of the dot impact printer constructed as described above, the input side voltage of the switching circuit converted into a digital value is output to the printing speed selection means. The printing speed selection means selects a printing speed according to the power consumed by the printing mechanism unit from the table storage means based on the voltage, and outputs a control signal to the drive circuit.

Therefore, according to the present invention, the voltage varying according to the power consumed by the printing mechanism is detected and the printing is performed at the printing speed corresponding to the voltage, so that a sufficient impact force can be maintained and the printing speed can be improved. It is possible to print without dropping sharply and improve the throughput of the printer.

[0011]

Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are given the same reference numerals.

First Embodiment FIG. 2 is a functional block diagram showing the basic configuration of the present invention. The analog / digital converting means 7a inputs the output V1 of the switching circuit of the power supply circuit 6, converts it into a digital value, and outputs it to the printing speed selecting means 7b. The printing speed selection means 7b selects a printing speed according to the power consumed by the printing mechanism unit from the table storage means 11a based on the voltage, and outputs a control signal to the I / O driver 10. By the way, the analog / digital conversion means 7a, the printing speed selection means 7b, and the table storage means 11a are a microcomputer.
It can be configured by a computer.

FIG. 1 is a block diagram showing the schematic arrangement of the dot impact printer of the first embodiment. The dot impact printer controls the print mechanism 1, such as a print head 1, a spacing motor 2 for moving the print head 1 in a line direction, and a line feed motor 3 for feeding paper, and a print mechanism unit 4. The unit 5 and the power supply circuit 6 for supplying electric power to the printing mechanism unit 4 and the control unit 5 are provided.

The control unit 5 includes a central processing unit 7 (hereinafter CPU 7).
And a memory 8 and a gate array 9, and an I / O driver 10 is provided between the gate array 9 and the printing mechanism section 4. The power supply circuit 6 has a mechanism drive power supply circuit described later and a logic drive power supply circuit (not shown), and the output of the mechanism drive power supply circuit is input to the I / O driver 10.
The output of the power supply circuit for logic drive is the CPU 7, the memory 8,
It is input to the gate array 9.

The memory 8 is a memory for storing a control program.
It includes a read-only memory 11 (hereinafter referred to as ROM 11) and a random access memory 12 (hereinafter referred to as RAM 12) that stores print data and the like. CPU7 is ROM11
The print data is read out from the RAM 12 by the control program, and the output of the mechanism driving power supply circuit is supplied to the print mechanism section 4 through the I / O driver 10 based on the print data.

FIG. 3 is a mechanism driving power supply circuit diagram of the first embodiment. AC 100V having a power switch SW is connected to the primary side of the transformer 13, and the smoothing circuit 1 is connected to the secondary side.
4 and a switching circuit 15 for preventing the output voltage Vp from changing due to the fluctuation of the output voltage V1 of the smoothing circuit 14 or the load. The smoothing circuit 14 is a full-wave rectifying diode.
It has terminals D1 to D4 and a smoothing capacitor C1. The switching circuit 15 includes a switching transistor Tr, a switching transistor control circuit 16, a back electromotive force regeneration diode D5, and a switching circuit coil L1.
And a smoothing capacitor C2.

The input side of the switching transistor Tr,
That is, the collector terminal is connected to an A / D converter incorporated in the CPU 7, as shown in FIG. 1, and the CPU 7 monitors the voltage V1 by converting it from an analog value to a digital value.

FIG. 4 is a load characteristic diagram of the switching circuit shown in FIG. A polygonal line 17 shows the relationship between the voltage V1 on the input side of the switching circuit and the load current, and a polygonal line 18 shows the relationship between the voltage Vp on the output side of the switching circuit and the load current. When the load current is 0 [A], the voltage V1 is 50 [V] and the voltage Vp is 40 [V]. While the load current increases from 0 [A] to about 1.5 [A], the voltage V1 decreases, but the voltage Vp is held at 40 [V] by the switching circuit. However, if the load current exceeds 1.5 [A], the voltage V
p also begins to decrease.

Voltages Vref1, Vref2, Vref3
Are thresholds used by the CPU 7 to monitor the voltage V1.

FIG. 5 is an explanatory diagram of a table in which the printing speed is associated with the voltage band of the voltage V1 used when the CPU controls the printing speed based on the voltage V1. If the voltage V1 is equal to or higher than the threshold value Vref1, printing is performed at the specified print speed, and Vre
If f1> V1 ≧ Vref2, 75% of the specified printing speed
When Vref2> V1 ≧ Vref3, the printing is performed at 50% of the specified printing speed. The table is stored in the ROM 11 as a table storage means. The CPU 7 inputs the voltage V1 as the printing speed selecting means, and the ROM 1
The printing speed is selected from 1 and the spacing motor 2 and the line feed motor 3 are driven.

FIG. 6 is a flow chart for explaining the operation of the first embodiment.
It is a chart. In step S1, the CPU 7 periodically detects the voltage V1 during the printing operation. CP in step S2
The U7 reads the threshold Vref1 from the ROM 11 and compares it with the voltage V1 to check whether the voltage V1 is equal to or higher than the threshold Vref1.
If not, go to step S4. Step S3
Then, the CPU 7 prints the print speed at the specified print speed. In step S4, the CPU 7 reads the threshold value Vref from the ROM 11.
2 is read out and compared with the voltage V1, and the voltage V1 is equal to the threshold value Vr.
Whether or not it is ef2 or more is checked, and if it is the threshold Vref2 or more, the process proceeds to step S5, and if not, the process proceeds to step S6.

In step S5, the CPU 7 prints at a print speed of 75% of the specified print speed. As shown in FIG. 4, the output side voltage Vp of the switching circuit is constant voltage 40
Although it slightly drops from [V], it exceeds the voltage value Vs,
Since the impact force sufficient to drive the dot pins of the print head 1 is retained, the printed characters do not fade. In step S6, the CPU 7 reads the threshold value Vref3 from the ROM 11 and compares it with the voltage V1 to obtain the voltage V1.
Is greater than or equal to the threshold value Vref3, and the threshold value Vr
If ef3 or more, the process proceeds to step S7, and if not, the process proceeds to step S8. In step S7, the CPU 7 prints at a print speed of 50% of the specified print speed. At the time of switching the printing speed, the voltage value Vs is still exceeded, and the printing speed is switched while maintaining a sufficient impact force. In step S8, the CPU 7 stops printing and stops the 2-pass printing mode.
And print it.

According to the first embodiment, since the printing duty of the printer is indirectly known from the voltage V1 on the input side of the switching circuit at a certain time to determine the printing speed, a transformer having a small capacity is used. Even if it is, the printing duty can be flexibly accommodated.

The configuration of the second embodiment the second embodiment is the same as the first embodiment, differs from the expected voltage Vt after t seconds CPU7 as expected voltage calculation means detects the voltage V1 This is the point of controlling the printing speed. That is, if the voltage V1 at a certain point is determined,
The voltage Vt after t seconds is obtained from the load voltage characteristic formula Vt = V1 (1-e-t / K) ... (1).

The constant K is a constant determined from the load resistance and the load reactance, and is previously obtained by an experiment.

FIG. 7 is a flow chart for explaining the operation of the second embodiment.
It is a chart. The difference from the first embodiment is step S12.
The other steps are the same in that the is added. In step S11, the CPU 7 periodically detects the voltage V1 during the printing operation. In step S12, the CPU 7 obtains the voltage Vt after t seconds by using the mathematical expression (1). CPU7 in step S2
Reads the threshold value Vref1 from the ROM 11 to obtain the voltage Vref
By comparing with t, it is checked whether or not the voltage Vt is equal to or higher than the threshold value Vref1, and if it is equal to or higher than the threshold value Vref1, the process proceeds to step S3, and if not, the process proceeds to step S4. C in step S3
The PU 7 prints at a specified print speed.

In step S4, the CPU 7 reads the threshold value Vref2 from the ROM 11 and compares it with the voltage Vt to check whether the voltage Vt is equal to or higher than the threshold value Vref2. If the voltage value is equal to or higher than the threshold value Vref2, the process proceeds to step S5. Proceed to S6. In step S5, the CPU 7 prints at a print speed of 75% of the specified print speed. In step S6, the CPU 7 reads the threshold value Vref3 from the ROM 11 and compares it with the voltage Vt to check whether the voltage Vt is equal to or higher than the threshold value Vref3. If the threshold value Vref3 or higher, the process proceeds to step S7. If not, the process proceeds to step S8. . In step S7, the CPU 7 prints at a print speed of 50% of the specified print speed. In step S8, the CPU 7 stops printing and switches to the 2-pass printing mode to print.

According to the second embodiment, the expected voltage V after t seconds from the voltage V1 on the input side of the switching circuit at a certain time.
Since the print speed is determined by obtaining t and indirectly predicting the print duty of the printer, the print duty can be flexibly dealt with as compared with the first embodiment.

[0029]

Since the present invention is configured as described above, it has the following effects.

A table storage means for storing a table in which the voltage band of the input side voltage of the switching circuit and the printing speed are associated with each other, and the input side voltage of the switching circuit are input to print from the table storage means. By providing the printing speed selecting means for selecting the speed and outputting it to the control unit, printing is performed at the printing speed according to the output voltage of the secondary side power supply for supplying power to the printing mechanism unit, so that the printer output Can improve

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment.

FIG. 2 is a functional block diagram showing a basic configuration of the present invention.

FIG. 3 is a mechanism driving power supply circuit diagram of the first embodiment.

FIG. 4 is a load characteristic diagram of the switching circuit of the first embodiment.

FIG. 5 is an explanatory diagram of a table in which a voltage band of voltage V1 and a printing speed are associated with each other.

FIG. 6 is a flowchart for explaining the operation of the first embodiment.

FIG. 7 is a flowchart for explaining the operation of the second embodiment.

FIG. 8 is a load characteristic diagram of a conventional switching circuit.

[Explanation of symbols]

 4 Printing mechanism part 5 Control part 6 Power supply circuit 7 CPU

Claims (2)

[Claims] 1. A switching circuit is provided on the secondary side of a power supply circuit, and the output of the switching circuit is I / O of a printing mechanism section.
In a dot impact printer that supplies a drive current to an O driver and controls a drive current according to a control signal from a control unit to rotate a spacing motor to control a printing speed, increase the drive current supplied to the printing mechanism unit. A table storing means for storing a table in which the voltage band of the input side voltage of the switching circuit corresponding to the printing speed and the printing speed are linearly responded to, and the input side voltage of the switching circuit is input to digitally input. The output of the analog / digital conversion means for converting into a value and the output of the analog / digital conversion means are input to select the printing speed from the table storage means, and a control signal corresponding to the printing speed is output to the I / O driver. A dot impact printer, comprising: 2. The dot impact printer according to claim 1, wherein the output of the analog / digital conversion means is input to obtain a predetermined voltage after t seconds from a load voltage characteristic formula, and then the printing speed selection means is provided. A dot impact printer having an expected voltage calculation means for outputting.