JPH07323583A - Printing head and printing control device - Google Patents

Abstract

PURPOSE:To provide a printing head and a printing control device capable of realizing the printing control corresponding to proper temp. by detecting the temp. corresponding to the form of a magnet coil. CONSTITUTION:In a printing head driving a needle 8 using a plurality of magnet coils 18, a diode circuit constituted by arranging a plurality of diodes 24 on the head substrate 20 attached to a yoke 12 corresponding to the arranging form of the magnet coils and connecting them in series and a temp. detection circuit applying a current or voltage to the diode circuit to take out voltage showing a temp. change through the diode circuit are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head and a print control device used in a serial impact dot printer.

[0002]

2. Description of the Related Art Conventionally, in a serial impact dot printer, when high-density printing is continuously performed, a magnet coil heats up and becomes overheated. May be reduced. For this reason, a temperature detecting element is attached to the print head as a means for detecting a temperature rise, and when the print head reaches a reference temperature, the magnet coil does not reach an abnormal temperature due to a decrease in printing speed or the stop of printing operation. Such measures have been taken.

For example, as shown in FIG. 11, a hollow housing has a nose 102 and a rear casing 104.
The armature 106 and the needles 108 brazed to the tip of the armature 106 are provided therein by the number of printing pins. Armature 106
Is supported by a yoke 112 by an armature spring 110 installed on the rear casing 104, and one end of the reset spring 114 is installed on the yoke 112.
Thus, the needle 108 is pressed backward. Then, the armature 106 has a yoke 112.
By energizing and exciting the magnet coil 118 wound around the magnetic core portion 116, the needle 108 receives an attractive force, and the needle 108 selectively pops out from the tip portion of the nose 102.
As a result, printing is performed. Magnet coil 118
Are installed as many as the armatures 106, and are usually arranged in an annular shape.

In this printing operation, the magnet coil 118 is excited through the head substrate 120 installed on the surface of the yoke 112. This head substrate 12
One end of 0 is drawn out of the housing, and a drive current is applied to the connector 122.

As shown in FIG. 12, the head substrate 120 has a single thermistor 12 as a temperature detecting element.
4 has been implemented. The thermistor 124 is fitted in a through hole 126 formed in the head substrate 120.

The thermistor 124 is connected to a temperature control circuit as shown in FIG. Thermistor 12
A resistor 128 is connected in series to the 4 and the thermistor 124
And a series circuit composed of the resistor 128, the resistor 128 is grounded,
By connecting the thermistor 124 side to the power supply, a voltage Vt obtained by dividing the power supply voltage Vcc is generated at the intermediate connection point. This voltage Vt has a value depending on the temperature, and since the value is an analog value, it is converted into a digital value by the analog / digital (A / D) converter 130, and then is supplied to the microprocessor unit (MPU) 132. Is read. The MPU 132 has an RO as a storage element.
An M134 is connected, and a temperature control program is stored in this ROM134. By executing this program, the MPU 132 controls the operation of the print head according to the temperature rise.

The control of this print head is as follows. The MPU 132 prints the data received by the external interface, but when the temperature detection data converted into a digital value by the A / D converter 130 reaches a set value or more, it controls the head driver and the carriage driver to perform bidirectional printing. The print head is protected from overheating so that the magnet coil 118 does not rise above a predetermined temperature by reducing the load on the magnet coil 118, such as changing from one-way printing to printing in one direction, reducing printing speed, and stopping printing.

[0008]

By the way, in the conventional print head, the single thermistor 124 detects the local temperature, and cannot detect the entire temperature. That is, when the heat generated by the magnet coil 118 near the thermistor 124 is fast and accurate temperature detection is possible, when the magnet coil 118 distant from the thermistor 124 is intensively used. For example, in linear printing, the generated heat is conducted through the yoke 112 and is transmitted to the thermistor 124, so that the temperature detection becomes uneven depending on the place of heat generation, which causes burnout of the magnet coil 118 and the like.

In order to prevent such uneven temperature detection, it is conceivable to lower the set temperature. Although the set temperature can be prevented from overheating the magnet coil 118, the printing speed is lowered and the printing is stopped more rapidly, which significantly reduces the printing speed when high-density printing is continuously performed.

Also, the use of a plurality of thermistors 124 increases the manufacturing cost of the print head,
Not practical.

Therefore, it is an object of the present invention to provide a print head and a print control device capable of realizing the print control corresponding to an appropriate temperature by detecting the temperature corresponding to the form of the magnet coil.

[0012]

The print head of the present invention comprises:
As illustrated in FIG. 1, a plurality of magnet coils (1
A print head for driving a needle (8) using a head substrate (2) mounted on a yoke (12).
A diode circuit (26) in which a plurality of diodes (24) are installed corresponding to the arrangement form of the magnet coil on the 0) side and the diodes are connected in series, and a current or a voltage is applied to the diode circuit. A temperature detection circuit (2 that extracts a voltage representing a temperature change through the diode circuit
8) and.

In the print head of the present invention, a voltage that depends on temperature is generated in a diode circuit composed of diodes. As an example, a constant current is applied to the diode circuit from a constant current source, and the voltage depends on the temperature. Includes those designed to generate voltage.

Further, in the print head of the present invention, as another example, a voltage depending on temperature is generated in the diode circuit, and the diode circuit has a resistor (resistor 5).
4 or a resistor 56) is connected in series, and a constant voltage is applied to this series circuit to generate a voltage according to the temperature.

The print control device of the present invention is a print control device using a print head that drives a needle using a plurality of magnet coils, and the magnet coils are arranged on the head substrate side attached to the yoke. A diode circuit in which a plurality of diodes are installed according to the form, and each diode is connected in series; and a temperature detection circuit that supplies a current or voltage to the diode circuit and extracts a voltage representing a temperature change through the diode circuit. The operation of the print head is controlled by the temperature detection output of the temperature detection circuit.

[0016]

In the print head of the present invention, a plurality of diodes are used as the temperature detecting element, and the diodes are arranged corresponding to the arrangement form of the magnet coil, and even if heat is generated at any place of the magnet coil. The heat generation can be detected by a diode corresponding to the heat generation location. That is, since the diode has a temperature characteristic,
Generates voltage according to temperature change. The diodes are connected in series to form a diode circuit, and a current or voltage is applied to the diode circuit to form a temperature detection circuit. Therefore, the temperature detection circuit can obtain a voltage depending on the temperature change. Since multiple diodes are connected in series in the diode circuit, even if the voltage change of one diode is small, that value is added and extracted as a large voltage change according to the number of diodes in series. It is possible to improve the detection accuracy.

When a constant current is applied to a diode circuit composed of a series circuit of a plurality of diodes, a constant voltage is generated in the diode circuit by the constant current. Since each diode has a temperature characteristic, the generated voltage changes depending on the temperature, and the voltage indicating the temperature change is extracted.

If a resistor is connected in series to the diode circuit to form a voltage dividing circuit and a constant voltage is applied to this voltage dividing circuit, a voltage depending on the temperature can be taken out at an intermediate connection point between them. .

Further, in the print control apparatus of the present invention, the operation of the print head is controlled by the voltage depending on the temperature obtained by the diode circuit composed of a plurality of diodes and the temperature detection circuit, so that the abnormal heat generation of the magnet coil is caused. Can be suppressed. As the control of the print head, various controls such as changing bidirectional printing to unidirectional printing, reducing the printing speed, and temporarily stopping printing can be performed.

[0020]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment of the print head of the present invention. The hollow housing is formed by a nose 2 and a rear casing 4, and inside the arm housing 6, a needle 8 brazed to the tip thereof is provided for the number of printing pins. The armature 6 is supported by a yoke 12 by an armature spring 10 installed in the rear casing 4, and one end of the armature 6 is pressed by a reset spring 14 installed in the yoke 12 so that the needle 8 is directed rearward. Further, a plurality of magnetic core portions 16 are formed on the yoke 12 so as to correspond to the armatures 6, and each magnetic core portion 1
A magnet coil 18 is wound around 6. The magnet coils 18 are arranged in an annular shape as shown in FIG.

The head substrate 20 is provided on the rear surface of the yoke 12.
Is installed, one end of the head substrate 20 is pulled out to the outside of the housing, and the connector 22 is attached.

As shown in FIG. 3, a plurality of diodes 24, which are rectifying diodes, are arranged in the yoke 12 so as to correspond to the magnet coils 18 arranged in an annular shape. In the case of this embodiment, the arrangement of the magnet coils 18 is divided into angular ranges of 60 °, and the six diodes 24 are constituted so as to detect the temperature in each of the divided ranges. Each diode 24 is arranged so as to be embedded in the opening of the head substrate 20.

Next, FIG. 4 shows a first embodiment of a print control apparatus using the print head of the present invention. The six diodes 24 are connected in series in the forward direction to form a diode circuit 26.

In the temperature detecting circuit 28, a constant current source 30 is connected to the anode side of the diode circuit 26, and the cathode of the diode 24 on the terminal side of the diode circuit 26 is grounded. A constant current flows from the constant current source 30 to the diode circuit 26, and the constant current causes the diode circuit 26 to have a temperature-dependent voltage, that is, the output voltage V.
m occurs.

Since this voltage Vm is an analog value, it is analog / digital (A
/ D) is added to the converter 32. This A / D converter 32
The voltage Vm converted into a digital value by is applied to the microprocessor unit 34 which is an arithmetic processing means. The microprocessor unit 34 includes a ROM 3 as a storage element that stores a temperature control program and the like.
6. An I / O port 38, which is a data input / output unit, is connected. The I / O port 38 has an external interface (I / F) 4 for linking with external control means and the like.
0 is connected, and a head driver 42, a carriage motor driver 44, and a paper feed motor driver 46 are connected as various driving means. External I /
A host computer is connected to F40. A print head 48 is connected to the head driver 42, a carriage motor 50 is connected to the carriage motor driver 44, and a paper feed motor 52 is connected to the paper feed motor driver 46.

The temperature detection and print control of the print head will be described.

When the forward voltage generated in each diode 24 by the constant current is Vf and the number of series circuits is n,
The output voltage Vm is Vm = Vf × n (1) In the case of this embodiment, since it is composed of six diodes 24 and n = 6, the equation (1) is Vm = 6.
It becomes Vf.

The relationship between the forward voltage Vf and the forward current If in the small current region of each diode 24 is as shown in FIG. 5, which is expressed by the following equation. If = Is × (exp (qVf / KT) -1) (2) where Is: reverse saturation current T: absolute temperature (K) K: Boltzmann constant

[Equation 1] q: electron charge

[Equation 2] In the equation (2), the reverse saturation current Is has a temperature coefficient, but since its absolute value is small, its change is ignored and the forward current If is given to the constant current and is constant. It can be seen that the current If is inversely proportional to the temperature T.

Such a relationship varies depending on the semiconductor material and the structure of the diode 24. In the case of a silicon diode, for example, as shown in FIG. 6, when the forward current If is about 3 mA, the temperature coefficient is set. dVf is -2.
It becomes 3 mV / ° C.

Here, the output voltage Vm (2
5), output voltage Vm (100) at 100 ° C, 130 ° C
The output voltage Vm (130) at Vm (25) = 0.5 × 6 = 3 (V) (3) Vm (100) = 0.3275 × 6 = 1.965 (V) -(4) Vm (130) = 0.2585 x 6 = 1.551 (V) ... (5).

The output voltage Vm is converted into a digital value by the A / D converter 32 and read into the MPU 34. According to the program written in the ROM 36, the MPU 34 controls the transition from bidirectional printing to unidirectional printing, reduction of the printing speed, stop of printing, etc. when the A / D converted data shifts to a specific set value. Then, the magnet coil 18 is controlled so as not to overheat above a predetermined temperature.

FIG. 7 shows a flow chart of the temperature control program. With this control, when the temperature rises above 100 ° C, bidirectional printing is changed to unidirectional printing and 130 ° C
When the above is reached, the printing operation is stopped.

In step S1, print data is read through the external I / F 40. In step S2, A
The A / D conversion value, which is the temperature data from the / D converter 32, is read, and in step S3, Vm = 1.965V or less,
That is, the A / D converter 32 has 8 bits and its reference voltage is 5
When V is set, it is determined whether the A / D conversion value is 100 or less. If the A / D converted value is 101 or more, one line is printed by controlling the print head 48 and the carriage motor 50 in step S4, and the line feed is performed by controlling the paper feed motor 52 in step S5. Return to.
That is, when the detected temperature is less than 100 ° C., the normal printing operation is performed. If the A / D converted value is 100 or less, the process proceeds to step S6. In step S6, V
m = 1.551V or less, that is, it is determined whether the A / D converted value is 79 or less. If the A / D converted value is 79 or less, the process returns to step S2 and the A / D converted value is 80 or less. If it is above, one line is printed in step S7, and the carriage motor driver 44 is controlled to operate the carriage motor 50 with the operation of the print head 48 stopped in step S8, and the print head 48 is mounted. Carriage return operation that moves the carriage in the opposite direction and returns it to the start position of the next line is performed. Then, in step S9, the paper feed motor driver 46 is controlled to operate the paper feed motor 52 to perform line feed, and then the process returns to step S1. That is, when the detected temperature is 100 ° C. or higher and lower than 130 ° C., the one-way printing operation is performed. Then, when the temperature of the magnet coil 18 decreases and the A / D conversion value shifts to 100 or more, the original bidirectional printing is restored.

When the temperature rise reaches 130 ° C., the checking operation is repeated until the temperature rises below 130 ° C., during which the printing operation is stopped. As a result, when the temperature of the magnet coil 18 decreases and the detected temperature shifts to less than 130 ° C., one-way printing is restarted to perform one-way printing, and the temperature further decreases, and the detected temperature is 100 ° C. If less, the normal bidirectional printing operation is performed.

Next, FIG. 8 shows a second embodiment of a print control device using the print head of the present invention. In the print control device of the second embodiment, the diode circuit 26 has a resistor 54.
Are connected in series, and the power source voltage Vcc is applied as a constant voltage to a series circuit including the diode circuit 26 and the resistor 54 with the resistor 54 side being the ground side. Other configurations are the same as those in the first embodiment, and the same reference numerals are given and the description thereof is omitted.

According to such a configuration, the temperature detection circuit 2
The output voltage Vn of 8 is Vn = Vcc-Vf * n (6), and assuming that the resistance value of the resistor 54 is R1, the forward current If of the diode 24 is If = Vn / R1 ... ( 7) Also in the case of the second embodiment, the number of connected diodes 24 is n = 6.

When Vcc = 5V, the output voltage Vn (25) at 25 ° C. and the output voltage Vn at 100 ° C.
The output voltage Vn (130) at (100) and 130 ° C. is
From the formula (6), Vn (25) = 2 (V) ... (8) Vn (100) = 3.035 (V) ... (9) Vn (130) = 3.449 (V).・ It becomes (10). The output voltage Vn of the equations (8) to (10) is a value on the assumption that the forward current If = constant, and the forward current If of the temperature detection circuit 28 shown in FIG. 8 is not constant.
However, if R1 = 820Ω, for example, the forward current If (25) at 25 ° C. and the forward current If at 100 ° C.
Forward current If (130) at (100), 130 ° C
Can be obtained by substituting the output voltage Vn into the equation (4), and If (25) = 2.44 (mA) ... (11) If (100) = 3.70 (mA). (12) If (130) = 4.21 (mA) (13), the forward current If is almost constant, and the output voltage Vn is expressed by the equations (8) to (10). The value is retrieved.

Next, FIG. 9 shows a control program of the print control apparatus shown in FIG. In step S11,
Print data is read from the external I / F 40, and step S
In 12, the A / D converted value of the output voltage Vn is read, and in step S13, the A / D converted value is Vn = 3.035.
Whether or not it is V or more, that is, if the A / D converter 32 is 8 bits and its reference voltage is 5 V, it is determined whether or not the A / D converted value is 155 or more. If the A / D converted value is less than 155, the process proceeds to step S14, one line is printed, line feed is performed in step S15, and then step S15.
Return to 1. Further, in step S13, the A / D conversion value is 15
If it is 5 or more, the process proceeds to step S16. In step S16, it is determined whether or not Vn = 3.449 V or more, that is, whether the A / D conversion value is 176 or more. If it is 176 or more, the process returns to step S12, and if it is less than 176, step S16. One line printing is performed in S17, and the carriage return operation is performed in S18 and then S
After shifting to 19 and executing the line feed, the process returns to step S11. As described above, even when the print control device shown in FIG. 8 is used, the temperature control can be realized similarly to the first embodiment, and the temperature rise of the magnet coil 18 can be suppressed.

Next, FIG. 10 shows a third embodiment of a print control apparatus using the print head of the present invention. This third
In the embodiment, a resistor 56 is connected in series to the diode circuit 26, and a constant voltage source 58 is connected to this series circuit with the diode circuit 26 on the ground side to configure the temperature detection circuit 28. The constant voltage source 58 is set to, for example, 5V.
Even with such a configuration, the temperature control operation similar to that of the first embodiment can be realized.

In each embodiment, six diodes 2 are used.
Although the temperature detection circuit 28 is configured by a series circuit of four, the number of connected diodes 24 is not limited to six, and the temperature detection circuit 28 does not need to be single.
In that case, if the number of connected diodes 24 is reduced,
The conversion value of the temperature detection voltage becomes small, and the detection accuracy decreases. Further, when the number is large, it contributes to increase the temperature detection accuracy, but when the number is too large, the value of the output voltage exceeds the reference voltage of the A / D converter 32 and the value is set high. Since it is necessary, setting the number of diodes 24 to about 6 is advantageous in circuit design.

[0042]

According to the present invention, the following effects can be obtained. a. The temperature rise of the print head can be detected by an inexpensive diode without using an expensive temperature detecting element such as a thermistor. b. By arranging multiple diodes corresponding to the shape of the magnet coil, the temperature detection position does not deviate, and even though the voltage change in one diode is small, it depends on the temperature due to its serialization. The voltage value can be increased and the temperature detection accuracy can be improved. c. The temperature-dependent voltage obtained by the diode can be used to perform print control of the print head, and optimal print control can be realized without impairing high-speed printing in high-density printing.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a print head according to the present invention.

FIG. 2 is a sectional view of the print head shown in FIG. 1 taken along the line AA.

FIG. 3 is a sectional view of the print head shown in FIG. 1 taken along the line BB.

FIG. 4 is a block diagram showing a first embodiment of a print control device of the present invention.

FIG. 5 is a diagram showing operating characteristics of a diode.

FIG. 6 is a diagram showing temperature characteristics of a diode.

FIG. 7 is a flowchart showing an operation of the print control apparatus shown in FIG.

FIG. 8 is a block diagram showing a second embodiment of the print control device of the present invention.

9 is a flowchart showing the operation of the print control device shown in FIG.

FIG. 10 is a block diagram showing a third embodiment of the print control device of the present invention.

FIG. 11 is a vertical sectional view showing an example of a conventional print head.

12 is a cross-sectional view of the print head shown in FIG. 11 taken along the line D-D.

13 is a block diagram showing a part of a print control device using the print head shown in FIG.

[Explanation of symbols]

 8 needle 12 yoke 18 magnet coil 20 head substrate 24 diode 26 diode circuit 28 temperature detection circuit 54, 56 resistance

Claims (4)

[Claims] 1. A print head for driving a needle using a plurality of magnet coils, wherein a plurality of diodes are installed on a head substrate side attached to a yoke in accordance with the arrangement form of the magnet coils, and each diode is arranged. A print head comprising: a diode circuit formed by connecting in series with each other; and a temperature detection circuit that supplies a current or a voltage to the diode circuit and extracts a voltage indicating a temperature change through the diode circuit. 2. The print head according to claim 1, wherein a constant current is applied to the diode circuit from a constant current source to generate a voltage according to temperature. 3. A resistor is connected in series to the diode circuit, and a voltage according to the temperature is generated by applying a constant voltage to the series circuit. Print head. 4. A print control device using a print head for driving a needle using a plurality of magnet coils, wherein a plurality of diodes are provided on a head substrate side attached to a yoke corresponding to the arrangement form of the magnet coils. A diode circuit in which each diode is connected in series, a temperature detection circuit that supplies a current or voltage to this diode circuit and extracts a voltage that represents a temperature change through the diode circuit, and a temperature detection circuit of this temperature detection circuit. A print control device characterized in that the operation of the print head is controlled by output.