JP2878433B2 - Printing pressure switching device - Google Patents

Description

The present invention relates to a printing pressure switching device in a wire dot printer.

2. Description of the Related Art Conventionally, a wire dot printer using a wire dot print head has advantages such as a high degree of freedom of a print medium and the ability to use copy paper, and has been in high demand.

The print head used in the wire dot printer drives a wire by a permanent magnet or a magnetic attractive force of a magnet, and is classified into a plunger type, a spring charge type, and a clapper type according to the type of the magnet assembly.

Of these, the spring-charged type has an armature to which a printing wire is fixed is swingably supported by a biasing leaf spring, and the armature is previously attracted to the core by a permanent magnet against the elastic force of the biasing leaf spring. When printing, the coil wound around the core is excited to generate a magnetic flux in a direction opposite to the permanent magnet, thereby releasing the armature.

In the wire dot printer having the above configuration, printing is often performed on a copy medium due to the characteristic and structure of performing printing using the impact of a printing wire, and it is an important issue to improve the print quality during copying. Has become.

The wire dot printer uses an attractive force of a magnet excited by passing an electric current through a coil to drive a print wire to transfer ink of an ink ribbon to a medium.

 FIG. 2 is a drive circuit diagram of a conventional printing pressure switching device.

A plurality of printing wires are used to form a character. Here, the driving of one pin will be described.

In FIG., L _n is the coil in the print head, the magnet is excited by supplying a predetermined time the drive voltage + 60V to the coil L _n. Change the print wire of the impact strength (impact) is the drive voltage supply time of the coil that directly affect, by the T ₂ to turn on the T ₁ times the dot side transistor T _r2 to turn on the common side transistor T _r1 Time Is done. The time T ₁ is created by the farm or hard, to synchronize the timing of the phase switching spacing motor ▲ ▼ provided by the signal.
Further, T ₂ hours is created by entering the delay circuit ▲ ▼ signals. That is, ▲ ▼
When the signal rises, a current flows from the power supply + 5V via a resistor R _1, it is charged in the capacitor C _1, the time comparator
COM ₁ (-) input terminal Voltage rises. Meanwhile, the comparator COM ₁
The reference voltage V _c = 5R ₃ / (R ₂ + R ₃ ) obtained by dividing the voltage of the resistor R ₂ and the variable resistor R ₃ is input to the (+) input terminal of the switch.

Therefore, the output side of the comparator COM ₁ There the pulse of the reference voltage V _c only while lower + 5V is generated, it is to turn on the dot side transistor T _r2 T ₂ hours only. Impact strength of the thus printed wires, after adjusting the T ₂ hours by the variable resistor R ₃ becomes constant intensity, becomes printed pressure constant.

(Problems to be Solved by the Invention) However, in the printing pressure switching device having the above configuration, the impact force of the printing wire is constant regardless of the type of the medium, so that the characteristics of the medium (especially a copy medium) and the printing Depending on the characteristics of the head, the print density (copy density) may be lower at low temperatures than at normal temperatures, and characters may not be legible.

Therefore, if the driving force is extended to increase the impact force of the printing wire, the life of the ink ribbon is shortened, and the wear of the printing wire becomes severe.

In addition, although a method of detecting the temperature with a temperature thermistor and varying the impact force is provided, immediately after the printer device is installed at room temperature and heating is started in the early morning, the room temperature rises sharply. The temperature of the media or printhead cannot follow it. In such a case, the impact force decreases as the room temperature rises,
Sufficient print density (copy density) cannot be obtained.

An object of the present invention is to provide a printing pressure switching device capable of solving the problems of the above-described conventional printing pressure switching device and preventing print quality from deteriorating due to a temperature difference inside and outside a wire dot printer. I do.

(Means for Solving the Problems) For this purpose, a printing pressure switching device according to the present invention includes an armature having a printing wire fixed to a tip thereof, a core disposed opposite to the armature, and a core wound around the core. The present invention is applied to a wire dot printer provided with a coil for driving the above-mentioned armature when energized.

A drive current generating means for generating a drive current flowing through the coil; a means for detecting an ambient temperature outside the wire dot printer; a means for determining a temperature change rate of the detected ambient temperature; And an impact force varying means for sending a signal corresponding to the driving current to the driving current generating means and changing a waveform of the driving current generated by the driving current generating means.

Further, the impact force changing means changes the impact force when the temperature change rate is equal to or less than a set value when the ambient temperature exceeds the temperature at which the impact force is changed, and the temperature change rate is higher than the set value. In this case, there is provided a means for not changing the impact force for a set time.

(Operation) According to the present invention, as described above, the printing pressure switching device includes an armature having a printing wire fixed to the tip, a core disposed opposite to the armature, and a core wound around the core and energized. To a wire dot printer provided with a coil for driving the above armature.

A drive current generating means for generating a drive current flowing through the coil; a means for detecting an ambient temperature outside the wire dot printer; a means for determining a temperature change rate of the detected ambient temperature; And an impact force varying means for sending a signal corresponding to the driving current to the driving current generating means and changing a waveform of the driving current generated by the driving current generating means.

Further, the impact force changing means changes the impact force when the temperature change rate is equal to or less than a set value when the ambient temperature exceeds the temperature at which the impact force is changed, and the temperature change rate is higher than the set value. In this case, there is provided a means for not changing the impact force for a set time.

In this case, the ambient temperature outside the wire dot printer is detected, and the temperature change rate of the detected ambient temperature is determined.

When the ambient temperature exceeds the temperature at which the impact force is changed, the impact force is changed when the temperature change rate is equal to or less than the set value, and when the temperature change rate is higher than the set value, the impact force is changed for the set time. Is not changed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a printing pressure switching device showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes CPU, 2 is a memory, 3 clock LSI circuits, 4 is a temperature sensing circuit connected to the thermistor TH _1. Also, 5 is a print dot control circuit, print timing generating circuit 6, the printing impact variable circuit 7, which consists of print data latch circuit 8 and the printing control driver 9, the drive to the coil L _n by the indicia shaped control driver 9 An electric current flows.

FIG. 3 is a temperature detection circuit diagram in the printing pressure switching device of the present invention.

In the figure, the thermistor TH ₁ is attached such as a wire dot printer case, it is connected to the resistor R ₁ in series. The resistance of the thermistor TH ₁ along with the temperature changes changes, and the resistance value at temperature t [℃] and x [Ω], the comparison voltage _{V F = 5x / (x +} R 1) (V) becomes each of comparators COM ₁ ~COM ₈ (-) input to the input terminal. On the other hand, the (+) input terminal of the comparator COM ₁ ~COM ₈ several criteria voltage divided by the plurality of resistors is inputted. Then, each of the comparators COM _{1 to} COM ₈
The output of the input to the input terminal of the temperature detection LSI (SENSE) 11, by entering from the CPU 1 ▲ ▼, so that the signal D ₀ to D ₇ are outputted onto the data bus. Thus, the room temperature at that time is determined stepwise by the 8-bit data.

FIG. 4 is a dot control circuit diagram in the printing pressure switching device of the present invention.

In FIG., L _n is the coil in the print head, the magnet is excited by supplying a predetermined time the drive voltage + 60V to the coil L _n. Driving voltage supply time of the coil directly affect the print wire of the impact strength (impact) is changed by T ₂ hours to turn on the T ₁ times the dot side transistor T _r2 to turn on the common side transistor T _r1 You. The time T ₁ is created by the farm or hard, to synchronize the timing of the phase switching spacing motor ▲ ▼ provided by the signal. Further, T ₂ hours is created by entering the delay circuit ▲ ▼ signals. That, ▲ ▼ the signal rises, a current flows from the power supply + 5V via a resistor R _1, is charged in the capacitor C _1, the time comparator CO
The (-) input terminal of M _A Voltage rises. On the other hand, the comparator COM _A
The reference voltage V _c = 5R ₃ / (R ₂ + R ₃ ) obtained by dividing the voltage of the resistor R ₂ and the variable resistor R ₃ is input to the (+) input terminal of the switch.

Therefore, on the output side of the comparator COM _A , There the pulse of the reference voltage V _c only while lower + 5V is generated, it is to turn on the dot side transistor T _r2 T ₂ hours only.

Comparator COM _A for creating wherein said T ₂ hours
Of (-) input terminal, the resistor _{R a1 ~R a8, R b1 ~R} b8 and open collector circuit eight accessory circuit formed by OC ₁ ~OC ₈ is added, open collector circuit OC ₁ ~OC The input of ₈ is connected to the output of the latch circuit LSI (LATC) 12.

Then, input the ▲ ▼ signal from CPU1 and
By inputting the D ₀ to D _7, it is possible to set the output of the open collector circuit OC ₁ ~OC ₈ to 0 V or open state.

For example, if the data FF _(H) is written to the latch circuit LSI 12, comparator COM _A (-) rising input voltage of the input terminal is a time constant T ₁ = R ₁ C _1, then the output of the comparator COM _A is T ₂
It becomes a pulse of time. When data FE _(H) is written to the latch circuit LSI12, the comparator COM _A (−)
The input voltage of the input terminal is Get up by. Therefore, Therefore, T ₂ <T ₁ . Therefore, the output of comparator COM _A has T ₁
A pulse shorter than the time is output, and the printing pressure decreases. In this manner, several levels of printing pressure can be obtained by the write data to the latch circuit LSI12.

FIG. 5 is a clock LSI circuit diagram in the printing pressure switching device of the present invention.

The clock LSI circuit has an LSI13. Once the year, month, day, hour, minute, and second are set, the time can be read at any time by the CPU1, and an interrupt signal (INT) is sent to the CPU1 at certain intervals. It can also be sent and free time counting is possible.

FIG. 6 is an operation flowchart of the printing pressure switching device of the present invention.

In this embodiment, the thermistor TH ₁ detects the + 10 ° C., and switches the impact force.

Steps S1 and S2 The temperature is detected by the temperature detection circuit 4 at the same time when the power is turned on.

Steps S3 to S5 If the temperature is equal to or higher than + 10 ° C., the impact force is set to a small value, and the temperature is detected at one-minute intervals.

Step S6 If the temperature is lower than + 10 ° C., the impact force is temporarily set to a large value.

Step S7: Clear the register of the temperature sensing number counter allocated to the memory to 0.

Steps S8 and S9 Temperatures are detected five times in total at minute intervals, and each time the temperature is detected is written to the temperature set register allocated on the memory.

Steps S10 and S11 It is determined whether the fifth temperature is equal to or lower than + 10 ° C., and if it is equal to or lower than 10 ° C., the process returns to step S7 to detect the temperature five times again.

Step S12 If the temperature is equal to or higher than 10 ° C., the CPU 1 calculates based on the data in the temperature set register to determine the degree of increase in the average temperature.

Step S13: The degree of rise in the average temperature is 1 (° C. /
Minutes) In the following cases, the impact force is changed to a small value because the temperature is not sharply increased.

Step S14 Next, when the degree of increase is 1 (° C./min) or more, the temperature is sharply increased, so the apparatus waits for about 30 minutes while the impact force is set to be large. When the temperatures of the medium and the print head rise, the temperature is detected five times again.

The printing pressure can be set not only in one stage but also in a plurality of stages, and the number of times the switching temperature is detected and the counting time can be freely set by each printer.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the gist of the present invention.
They are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, the print switching device includes an armature having a print wire fixed to a tip, a core disposed to face the armature, and The present invention is applied to a wire dot printer provided with a coil that is wound and that drives the above-mentioned armature when energized.

A drive current generating means for generating a drive current flowing through the coil; a means for detecting an ambient temperature outside the wire dot printer; a means for determining a temperature change rate of the detected ambient temperature; And an impact force varying means for sending a signal corresponding to the driving current to the driving current generating means and changing a waveform of the driving current generated by the driving current generating means.

Further, the impact force changing means changes the impact force when the temperature change rate is equal to or less than a set value when the ambient temperature exceeds the temperature at which the impact force is changed, and the temperature change rate is higher than the set value. In this case, there is provided a means for not changing the impact force for a set time.

That is, when the ambient temperature exceeds the temperature at which the impact force is changed, the impact force is changed when the temperature change rate is equal to or less than the set value, and when the temperature change rate is higher than the set value, the impact force is changed for the set time. Not changed.

Therefore, it is possible to prevent the print quality from deteriorating due to a temperature difference between the inside and outside of the wire dot printer.

[Brief description of the drawings]

FIG. 1 is a block diagram of a printing pressure switching device showing an embodiment of the present invention, FIG. 2 is a drive circuit diagram of a conventional printing pressure switching device, and FIG. 3 is a temperature detection circuit diagram of the printing pressure switching device of the present invention. FIG. 4 is a dot control circuit diagram of the printing pressure switching device of the present invention, FIG. 5 is a clock LSI circuit diagram of the printing pressure switching device of the present invention, and FIG. 6 is an operation flowchart of the printing pressure switching device of the present invention. is there. 1 ... CPU, 2 ... memory, 3 ... clock LSI circuit, 4 ...
Temperature detection circuit, 6 Print timing creation circuit, 7
Print impact variable circuit 8, print data latch circuit 9, print control driver.

Continuation of the front page (56) References JP-A-2-219660 (JP, A) JP-A-54-135019 (JP, A) JP-A-2-117844 (JP, A) JP-A-2-81643 (JP) , A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B41J 2/30

Claims (1)

(57) [Claims] 1. A wire dot printer comprising: an armature having a print wire fixed to a tip thereof; a core disposed to face the armature; and a coil wound around the core and driving the armature by energization. (A) a drive current generating means for generating a drive current flowing through the coil; (b) means for detecting an ambient temperature outside the wire dot printer; and (c) a detected ambient temperature. (D) sending a signal corresponding to the ambient temperature to the driving current generating means, and changing an impact force varying means for changing a waveform of the driving current generated by the driving current generating means. (E) the impact force varying means, when the ambient temperature exceeds the temperature at which the impact force is changed, the temperature change rate Change the impact force is equal to or less than the set value, the printing pressure switching device, characterized in that it comprises a means not only change the impact force setting time when the temperature change rate is higher than the set value.