JP2003075264A - Head driver ic temperature detection apparatus of ink jet type printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head driver IC temperature detection apparatus of an ink jet type printer that is not affected by noise and can simplify the configuration of a control section by a simple configuration. SOLUTION: With an anode voltage V in a diode 23 at each of head driver ICs 11a-11d, a digital reference value Vd that is set by a temperature-setting section 21 is compared with an analog reference value Va that is D/A-converted by a DA converter 22 within the head driver ICs. The head driver IC temperature detection apparatus 10 of an ink jet type printer is composed so that a digital signal can be transmitted to a control section 14 of a printer body 13 via a cable 12 when the anode voltage V becomes less than a specific voltage due to the temperature increase in each of the head driver ICs 11a-11d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting the temperature of a head driver IC of an ink jet printer, which is adapted to detect that the head driver IC has reached a predetermined temperature or higher in the head of the ink jet printer. Is.

[0002]

2. Description of the Related Art Conventionally, as an output device of a computer, an ink jet type color printer of a type that ejects ink of several colors from a recording head has been widely used, and an image processed by a computer or the like is printed in multiple colors and multiple gradations. It is widely used to For example, in an ink jet printer using a piezoelectric element as a driving element for ejecting ink, each piezoelectric element provided corresponding to a plurality of nozzles of a print head is selectively driven to generate each piezoelectric element. Ink droplets are ejected from the nozzles based on the dynamic pressure of the element, and the ink droplets are made to adhere to the printing paper, thereby forming dots on the printing paper and performing printing.

Here, each piezoelectric element is provided corresponding to a nozzle for ejecting an ink droplet, and is driven by a drive signal supplied from at least one head driver IC mounted in the print head. , Is designed to eject ink drops.

By the way, each head driver IC generates heat by driving, and the heat is radiated by ejected ink droplets. However, due to continuous driving or the like, sufficient heat is radiated by ink droplets. It may disappear. If printing is continued in such a state, the temperature of each head driver IC further rises and each head driver IC
C may be thermally destroyed.

Therefore, in the conventional ink jet printer, as shown in FIG. 8, paying attention to the fact that the anode voltage of the diode provided in each head driver IC changes depending on the ambient temperature. , For example, the anode voltages of the diodes in the four head driver ICs 1a, 1b, 1c, 1d are set to the cables 2a, 2b,
For example, ASI in the printer body 3 via 2c and 2d.
It is output to the control unit 4 configured by C.

Then, in the control section 4, the AD converter 5 converts the value into a digital value, and each head driver IC
Detecting the anode voltage of the diode, and based on these anode voltages, each head driver IC 1a, 1b,
The temperatures of 1c and 1d are detected. here,
Any of the head driver ICs 1a, 1b, 1c or 1
When the temperature of d becomes equal to or higher than the predetermined temperature, the control unit 4 temporarily stops the printing operation, and the head driver IC
The temperatures of 1a, 1b, 1c and 1d are lowered.

[0007]

However, in such a temperature detecting method for the head driver ICs 1a, 1b, 1c, 1d, each head driver IC 1a, 1d is used.
Cables 2a, 2 from b, 1c, 1d to the control unit 4
Since b, 2c, and 2d become relatively long, and analog signals pass through these cables 2a, 2b, 2c, and 2d, there is a problem that they are easily affected by noise and detection accuracy decreases. It was

Each head driver IC 1a, 1b,
The anode voltages from 1c and 1d are AD in the control unit 4.
Since it is converted into a digital signal by the converter, the detection time becomes long and the AD converter 5 is required in the control unit 4. Therefore, the control unit 4 including, for example, an ASIC becomes large.

Further, each head driver IC 1a, 1
cables 2a, 2b, 2 from b, 1c, 1d respectively
A signal is output to the control unit 4 via c and 2d, and
In the AD converter 5 in the control unit 4 of the printer body 3,
Signals are input from the head driver ICs 1a, 1b, 1c, 1d via the cables 2a, 2b, 2c, 2d, respectively. Therefore, the cables 2a, 2b,
The number of 2c and 2d is the same as the number of head driver ICs, the number of input pins of the control unit 4 is increased, and the cost is increased.
This is contrary to the trend of reducing the number of pins.

Therefore, an object of the present invention is to provide a head driver IC temperature detecting device for an ink jet printer, which has a simple structure and is not affected by noise and the structure of the control unit is simplified. It is in.

[0011]

In order to solve the above-mentioned problems, according to the present invention, when the anode voltage of the diode of each head driver IC is compared with a reference voltage in the head driver IC and is below a predetermined voltage. , A digital signal is sent to the control unit.

That is, in the head driver IC temperature detecting device of the ink jet printer according to the first aspect, the control unit of the printer main body, based on the anode voltage of the diode provided in the head driver IC of the ink jet printer, A head driver IC temperature detecting device for an ink jet printer, which detects whether the head driver IC temperature is higher or lower than a predetermined temperature, the temperature setting unit setting a digital reference value corresponding to a reference temperature for temperature detection, and a temperature setting unit. The DA converter for converting the digital reference value from the unit into an analog reference value is compared with the anode voltage of the diode and the analog reference value from the DA converter to determine whether the anode voltage of the diode is higher or lower than the analog reference value. Digital signals to the control unit of the printer Characterized in that a comparator for outputting Te, the contained within each head driver IC.

According to this structure, after the power of the ink jet printer is turned on, the digital reference value is set by the temperature setting section, so that the DA converter in the head driver IC sets the digital reference value to the analog reference value. It is converted and input to one input terminal of the comparator.

In this state, the comparator compares the anode voltage of the diode provided in the head driver IC with the analog reference value from the DA converter, and the comparator determines that the anode voltage of the diode is the analog reference value. When it is higher, the digital signal is made inactive, and when the anode voltage of the diode becomes lower than the analog reference value, the digital signal is made active.

During the printing operation, the control unit of the printer body
By monitoring the digital signal from the comparator provided in each head driver IC, it is possible to detect that each head driver IC has become higher than a predetermined temperature. Furthermore, when the control unit of the printer body detects that the temperature of each head driver IC becomes higher than the predetermined temperature as described above, the control unit temporarily suspends the printing operation, or in some cases, forcibly terminates the printing operation, thereby It is possible to prevent thermal destruction due to the temperature rise of the head driver IC.

Therefore, the signal for temperature detection output from each head driver IC to the controller of the printer main body is
Since it is a digital signal, even if the cable from the head driver IC to the control unit is long, it is hardly affected by noise, and the detection accuracy is improved. Further, since the control unit of the printer main body does not need an AD converter, the detection time is short, and the temperature of each head driver IC can be reliably detected even during a short time between printing operations.

According to another aspect of the head driver IC temperature detecting device of the present invention, the digital signals output from the comparators of the head driver ICs are independently output to the control unit of the printer body. And With this configuration, the digital signals from the comparators of the head driver ICs are independently output to the control unit of the printer body, so that the cable from the head driver ICs to the control unit of the printer body is Even if a failure such as a disconnection occurs in a part, it is impossible to detect the temperature of the head driver IC using the cable in which the failure has occurred, but it is possible to detect the temperature of the head driver IC using another cable. is there.

According to another aspect of the head driver IC temperature detecting device of the present invention, each head driver IC is further provided with an FET whose digital signal output from each comparator is input to its gate and whose output is open drain. It is characterized by According to this configuration, the FET is turned on / off by the digital signal from each comparator, and the output of the open drain is input to the control unit of the printer body.

According to another aspect of the head driver IC temperature detecting device of the present invention, the FET of each of the head driver ICs is used.
The digital signals output from the open drain of the printer are independently output to the control unit of the printer body. According to this configuration, the digital signal from the FET of each head driver IC is independently output to the control unit of the printer main body, so that one cable from each head driver IC to the control unit of the printer main body is output. Even if a failure such as a disconnection occurs in a part, it is impossible to detect the temperature of the head driver IC using the cable in which the failure has occurred, but it is possible to detect the temperature of the head driver IC using another cable. is there.

In the head driver IC temperature detecting device according to the present invention, the FET of each head driver IC is
The digital signals output from the open drains of the above are wired and connected to each other, and are output to the control unit of the printer main body by one cable. According to this configuration, since the digital signal from the FET of each head driver IC is output by the open drain, even if the outputs of the open drains of the FETs are wired and connected to each other, each FE is
The digital output signals of T are output to the control unit of the printer main body by one cable without interfering with each other.

Therefore, only one cable for temperature detection from a plurality of head driver ICs is required, the cost is reduced, and the number of input pins of the control unit of the printer body is small, which constitutes the control unit. This can contribute to the reduction of the pins of the ASIC.

In a head driver IC temperature detecting device for an ink jet printer according to a sixth aspect of the present invention, a digital signal output from each comparator is input to each base, and a bipolar transistor whose output is an open collector is used as the head driver IC. It is characterized by being prepared for each. According to this configuration, the bipolar transistor is turned on / off by the digital signal from each comparator, and the output of the open collector is input to the control unit of the printer body.

In the head driver IC temperature detecting device of the ink jet printer according to the present invention, the digital signals output from the open collectors of the bipolar transistors of each head driver IC are independently supplied to the control unit of the printer body. It is characterized in that it is output to. According to this configuration, the digital signal from the bipolar transistor of each head driver IC is independently output to the control unit of the printer main body, so that the cable from each head driver IC to the control unit of the printer main body. Even if a failure such as a disconnection occurs in a part of the cable, only the temperature of the head driver IC using the failed cable cannot be detected. However, the temperature of the head driver IC using another cable cannot be detected. It is possible.

According to another aspect of the head driver IC temperature detecting device of the ink jet printer of the present invention, the digital signals output from the open collectors of the bipolar transistors of each of the head driver ICs are wired and connected to each other, and It is characterized in that it is output to the control unit of the printer main body by a cable of a book. According to this configuration, since the digital signal from the bipolar transistor of each head driver IC is output from the open collector, even if the outputs of the open collectors of the bipolar transistors are wired and connected to each other, The digital output signals of the transistors are output to the control unit of the printer body by a single cable without interfering with each other.

Therefore, only one cable for temperature detection from a plurality of head driver ICs is required, the cost is reduced, and the number of input pins of the control unit of the printer main body is small, which constitutes the control unit. This can contribute to the reduction of the pins of the ASIC.

In the head driver IC temperature detecting device according to the ninth aspect, the temperature setting section of each head driver IC independently responds to individual conditions such as heat generation condition and heat dissipation condition of the head driver IC. It is characterized by being set. According to this configuration, each head driver I
The digital reference value of the temperature setting unit can be set for each head driver IC in response to the individual conditions of C and the variations in the characteristics of the diodes provided in the head driver IC.

According to a tenth aspect of the invention, there is provided a head driver IC temperature detecting device for an ink jet printer, wherein the temperature setting section of each head driver IC includes a digital data storage means having a predetermined number of bits, and the temperature is within the range of the number of bits. Is characterized in that the digital reference value can be set freely. With this configuration, the printer designer can freely set the digital reference value within the range of the number of bits while referring to the individual conditions and the like found by the preliminary measurement and the like for each head driver IC.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A head driver IC having a head driver IC temperature detecting device according to an embodiment of the present invention will be described with reference to the drawings. Since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 shows a head driver IC according to the present invention.
The structure of 1st embodiment of a temperature detection apparatus is shown. The head driver IC temperature detection device 10 includes a plurality (four in the illustrated case) of head driver ICs 11a and 11 provided in a printer head of an inkjet printer.
The anode voltage of each diode provided in b, 11c, and 11d is compared with the reference voltage, the comparison result is digitized, and output to the control unit 14 of the printer body 13 via the single cable 12. Is configured.

Here, each head driver IC 11a, 1
1b, 11c, and 11d have the same configuration, and are configured as head driver ICs for driving head nozzle units corresponding to, for example, yellow, magenta, cyan, and black colors. Therefore, the configuration of the head driver IC 11a will be described below.

FIG. 2 is a block diagram showing the structure of a portion of the head driver IC 11a which is involved in temperature detection. In FIG. 2, the head driver IC 11a includes a temperature setting unit 21, a DA converter 22, a diode 23, a comparator 24, and a FET 25.

The temperature setting unit 21 is composed of, for example, a register, and has a reference temperature Tre for temperature detection.
The digital reference value Vd corresponding to f is set. The DA converter 22 is adapted to convert the digital reference value Vd from the temperature setting section 21 into an analog reference value Va. The diode 23 is provided in the head driver IC 11a and has a resistor R on the anode side.
1 to the constant voltage power supply Vdd1 and the cathode side to ground.

In the illustrated case, the diode 23 is formed by connecting a plurality of (for example, four) diodes in series with each other. Where diode 2
As will be described later, the anode voltage of No. 3 has a characteristic of decreasing as the temperature of the head driver IC increases.

The anode voltage V of the diode 23 is input to the inverting input terminal of the comparator 24, and the analog reference value Va from the DA converter 22 is input to the non-inverting input terminal of the comparator 24. V is compared with the analog reference value Va. And
When the anode voltage V of the diode 23 is higher than the analog reference value Va, the comparator 24 outputs an L level digital signal and the diode 23.
When the anode voltage V of is lower than the analog reference value Va, an H level digital signal is output.

In the FET 25, the gate is connected to the output terminal of the comparator 24, the source is grounded, and the drain is the constant voltage power supply V via the resistor R2.
It is connected to dd2, and a digital signal is output from the drain as an open drain.
As a result, the FET 25 is off and its drain is held at the voltage of the constant voltage power supply Vdd2 when the output signal from the comparator 24 is at the L level, but the output signal from the comparator 24 is at the H level. Then it turns on and its drain is pulled to ground potential.

FIG. 3 shows a specific example of the configuration of the head driver IC 11a. 3, the head driver IC 11a is the head driver IC 11a shown in FIG.
And a plurality of flip-flop circuits 26 instead of the voltage setting unit 21 and the DA converter 22.
And a resistor group 27.

In the illustrated case, the flip-flop circuit 26 is composed of eight flip-flop circuits 26a. In these flip-flop circuits 26a, the latch signal is input to the clock terminal CLK, the setting signal is input to the D terminal, and the reference voltage Vref is input to the Vref terminal.

When H is set in the flip-flop, the output becomes Vref, and when L is set, it becomes GND. The head driver IC sends data for nozzle selection, for example, serially.
It is preferable to use this data for 0 to D7. In this case, the serial data is input to the shift register. For example, the last transmitted data is set to D0 to D7, the latch signal LAT dedicated to the temperature detection circuit is used, and the data is stored in the flip-flop.

The resistor group 27 includes seven resistors 1R and one resistor 2R connected in series between the non-inverting input terminal + of the comparator 24 and the ground, the anode side of each resistor 1R, and each flip-flop. 8 resistors 2R each connected to the output terminal Q of the switching circuit 26a.

As a result, each flip-flop circuit 26
By the combination of the setting signals input to the D terminal of a, the analog reference value Va input to the non-inverting input terminal + of the comparator 24 can be set in 256 steps from the voltage 0 to a voltage slightly lower than Vref. It has become.

Here, the analog reference value Va input to the non-inverting input terminal + of the comparator 24 takes into consideration the characteristic variation of the diode 23 incorporated in the head driver IC 11a to 11d, and the head driver IC.
The head driver ICs 11a to 11d are set before shipment so that the voltages correspond to the upper limit temperature T2 which is set slightly lower than the guaranteed temperature T1 of 11a to 11d.

Head driver IC according to the embodiment of the present invention
The temperature detecting device 10 is configured as described above and operates as follows. First, the setting of the analog reference value Va will be described.

As shown in FIG. 4, the head driver IC1
The diode 23 incorporated in each of 1a to 11d has a temperature-voltage characteristic width as shown by a straight line P and a straight line Q due to individual differences in characteristic variations. Variations in this characteristic include variations in inclination and variations in offset, but the variations in inclination have a large adverse effect. That is, the offset variation can be corrected by measuring the voltage at a certain temperature at the time of factory shipment.

First, consider the case where the initial measurement is not performed. Each diode 23 has a characteristic between the straight line P and the straight line Q. As a result, the intersection A of the straight line P indicating the upper limit of the characteristic and the upper limit temperature T2 slightly lower than the guaranteed temperature T1 of the head driver IC.
Is used as the threshold value of the anode voltage of the diode when the initial measurement is not performed, and the intersection B (temperature T3, voltage Vb) with the straight line Q of this threshold value is obtained.

In this way, when the initial measurement of the diode 23 is not performed, the threshold voltage Vb of the anode voltage set in consideration of the characteristic variation of each diode 23.
Will have a temperature range between points A and B, ie a temperature range of T3 to T2.

Therefore, depending on the characteristic variation of the diode 23, the temperature rise of the head driver IC is detected even at the temperature T3 which is significantly lower than the upper limit temperature T2.

On the other hand, the anode voltage of the diode 23 is actually measured at room temperature T0, and this anode voltage is used as the measurement voltage V0, and the point C is plotted on the temperature-voltage graph as shown in FIG. Then, from this point C, a straight line R parallel to a straight line P having a gentle slope (the sign of the slope is negative), which is the upper limit of the variation in the slope, is drawn to obtain an intersection D (temperature T2, voltage Vc) with the upper limit temperature T2. .

At this time, a straight line S parallel to the steep slope straight line Q which is the lower limit of the slope variation is drawn from the point C to obtain an intersection E (temperature T4, voltage Vc) with the voltage Vc. In this case, when the initial measurement of the diode 23 is performed, the threshold value of the anode voltage at the intersection D is in the temperature range between the points D and E, that is, the relatively narrow temperature range of T4 to T2, and the temperature detection accuracy is high. Will be improved.

In this way, when the threshold value Vc (= analog reference value Va) of the anode voltage of the diode 23 is determined, the digital reference value Vd corresponding to the analog reference value Va (for example, represented by [01001100]). The digital reference value Vd is set to the temperature setting unit 21.
To enter. As a result, the accuracy of temperature detection is improved by absorbing the characteristic variations of the individual diodes 23.

Next, the head driver IC temperature detecting device 1
The temperature detection operation of 0 will be described. When the power supply of the ink jet printer is turned on, in each head driver IC 11a to 11d, as an initialization operation, the voltage setting unit 21 performs digital measurement stored in a nonvolatile RAM or the like, which is initially measured and determined in a factory or the like. The reference value Vd is set, the DA converter 22 converts this digital reference value Vd into the analog reference value Va, and inputs it to the non-inverting input terminal of the comparator 24.

On the other hand, the diode 23 generates an anode voltage V corresponding to the temperature of the head driver ICs 11a to 11d. As a result, the comparator 24 compares the analog reference value Va with the anode voltage V, and when the anode voltage V is higher than the analog reference value Va, outputs a signal of L level, so that the FET 25 remains off. A voltage from the constant voltage power supply Vdd2 is applied to the output terminal 28, and an H level signal is output from the output terminal 28.

On the other hand, the head driver IC 11a
When the temperature of 11 to 11d rises with the printing operation and the anode voltage V of the diode 23 drops and becomes lower than the analog reference value Va, the comparator 24 outputs an H level signal and the FET 25 turns on. Therefore, the output terminal 28 is grounded, so that
A level signal will be output.

Here, the head driver ICs 11a to 11d have open drains at the output terminals 28 of the FETs 25, as shown in FIG. Head driver ICs 11a to 11d without interfering with
When any one of the FETs 25 turns on, this FET
Since it is dropped to the ground via 25, the signal from the output terminal 28 becomes an L level digital signal.

In this way, the head driver IC 11
If there is a possibility that the temperature of any of a to 11d exceeds the upper limit temperature T2 (it may be lower than T2 due to variations in inclination, but higher than T4), the comparator 24
Output changes to H level, the digital signal input from the open drain of the FET 25 to the control unit 14 changes from H level to L level, and the control unit 14 causes the temperature of one of the head driver ICs to reach the upper limit temperature T2. It is possible to detect that it may have been exceeded.

In this case, since the digital signals from the head driver ICs 11a to 1d are input to the control unit 14 via the single cable 12, the anode voltage from the diode 23 is not AD-converted as in the conventional case. Therefore, it is not necessary to provide an AD converter, and it is not necessary to provide a cable and an input pin for each head driver IC 11a to 11d. Therefore, the control unit 14 can be made compact and have a small number of input pins, and the cable for temperature detection can be a single core wire, so that the cost can be reduced.

The controller 14 operates as shown in FIG. 5, for example, when a digital signal for temperature detection is input from the head driver IC. In the flowchart of FIG. 5, first, in step ST1, the control unit 14 outputs a temperature detection command to each head driver IC 11a. The output of this temperature detection command is performed, for example, at the time when printing of each page or each line is completed.

Then, in step ST2, the control unit 14
When the digital signal XHOT input from each of the head driver ICs 11a to 11d via the cable 12 is at H level, each of the head driver ICs 11a to 11 is
Since all d are below the upper limit temperature T2, step ST
At 3, the count CNT = 0 (CNT is XHOT is L
As a variable indicating the number of times
After continuing the printing operation at T4, the process returns to step ST1.

If the digital signal XHOT is at the L level in step ST2, the control unit 14
Checks the count CNT in step ST5,
When NT ≦ 5, in step ST6, the count CNT = CNT + 1 is counted up, and in step ST7, the printing operation is paused for a predetermined rest time, and then in step ST8, the printing operation is restarted, Return to step ST1. The pause time in step ST7 may be constant or may be set to be longer as the value of CNT is larger.

On the other hand, in step ST5, CN
When T> 5, the control unit 14 determines in step ST9.
In step ST, it is judged that a fatal error has occurred.
At 10, the error processing including the forced termination of printing is performed, and the operation of the ink jet printer is stopped.
The process ends.

FIG. 6 shows a head driver IC according to the present invention.
2 shows a second embodiment of the temperature detecting device. In FIG. 6, the head driver IC temperature detection device 30 has the same configuration as the head driver IC temperature detection device 10 of FIG. 1, but differs only in the following points.

That is, the head driver IC temperature detecting device 3
0, each head driver IC 11a to 11d
The output signal for temperature detection is input to the control unit 14 of the printer body 13 via the cables 12a, 12b, 12c and 12d which are independent of each other.

According to the head driver IC temperature detecting device 30 having such a configuration, the head driver IC temperature detecting device 30 operates in the same manner as the head driver IC temperature detecting device 10 of FIG. 1, and the cables from the head driver ICs 11a to 11d are connected to the individual head drivers. Since each of the cables 11a to 11d is provided, for example, any one of the cables 12a, 12b, 12c or 1
When a failure such as disconnection occurs in 2d, only the temperature of the head driver IC using the cable with the failure cannot be detected, but the temperature of the head driver IC using another cable can be detected.

FIG. 7 shows a head driver IC according to the present invention.
7 shows a third embodiment of the temperature detecting device. In FIG. 7, the head driver IC temperature detecting device 40 has the same configuration as the head driver IC temperature detecting device 10 of FIG. 6, but differs in the following points.

That is, the head driver IC temperature detecting device 4
0, each head driver IC 11a to 11d
The output of the comparator 24 is directly connected to the cables 12a and 12 independent of each other without passing through the FET 25.
It is adapted to be input to the control unit 14 of the printer body 13 via b, 12c and 12d.

According to the head driver IC temperature detecting device 30 having such a structure, the head driver IC temperature detecting device 30 operates similarly to the head driver IC temperature detecting device 30 shown in FIG. 6, and the FET 25 is omitted, so that the number of parts can be reduced. Therefore, the cost can be reduced.

In the above-described embodiment, the head driver IC temperature detecting devices 10 and 30 each include four head driver ICs 11a to 11d, but the number of head driver ICs is not limited to four, and for example, seven head driver ICs are provided. It is obvious that the present invention can be applied to a color-color inkjet printer and a monochrome inkjet printer having only one head driver IC.

Further, in the above-mentioned embodiment, the characteristic variation of the diode 23 is taken into consideration when setting the analog reference value Va, but the present invention is not limited to this.
Individual conditions such as heat generation conditions and heat dissipation conditions depending on the arrangement of the individual head driver ICs 11a to 11d may be taken into consideration.

For example, when a plurality of head driver ICs are arranged side by side, the head driver ICs on both sides have relatively good heat dissipation conditions, but the inner head driver ICs have relatively poor heat dissipation conditions. In such a case, the analog reference value Va for the inner head driver IC may be set to a low value.

In this way, the analog reference value Va of each head driver IC may be set so that each head driver IC does not exceed the upper limit temperature T2 during the printing operation until the next temperature detection.

[0070]

As described above, according to the present invention, the signal for temperature detection output from each head driver IC to the control unit of the printer main body is a digital signal. Even if the cable to the control unit is long, it is less likely to be affected by noise and the detection accuracy is improved.

Further, since the AD converter is not required in the control section of the printer main body, the detection time is short and the temperature of each head driver IC can be surely detected even during a short time between printing operations.

Further, when the FETs are turned on / off by the digital signals from the respective comparators, and the outputs of the open drains thereof are AND-connected to each other and output to the control section of the printer main body by one cable. Since the digital signal from the FET of each head driver IC is output by the open drain,
Even if the outputs of the open drains of the FETs are AND-connected to each other, the digital output signals of the FETs are output to the control unit of the printer main body by one cable without interfering with each other.

Therefore, since only one cable for temperature detection from a plurality of head driver ICs is required, the cost is reduced and the number of input pins of the control unit of the printer body is small, and the control unit is configured. It can contribute to the reduction of the number of pins of the ASIC.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a head driver IC temperature detection device according to the present invention.

2 is a block diagram showing a main part of each head driver IC in the head driver IC temperature detection device of FIG. 1. FIG.

FIG. 3 is a diagram showing a specific configuration example of a main part of each head driver IC in FIG.

4 is a graph showing a procedure for setting an analog reference value in the head driver IC temperature detection device of FIG.

5 is a flowchart showing an example of control of a control unit in the head driver IC temperature detection device of FIG.

FIG. 6 is a block diagram showing the configuration of a second embodiment of the head driver IC temperature detection device according to the present invention.

FIG. 7 is a block diagram showing a main part of each head driver IC in a third embodiment of the head driver IC temperature detection device according to the present invention.

FIG. 8 is a block diagram showing a configuration of an example of a conventional head driver IC temperature detection device.

[Explanation of symbols]

10, 30, 40 Head Driver IC Temperature Detectors 11a, 11b, 11c, 11d Head Driver I
C 12, 12a, 12b, 12c, 12d Cable 13 Printer body 14 Control unit 21 Temperature setting unit 22 DA converter 23 Diode 24 Comparator 25 FET 26 Flip-flop circuit 27 Resistor group 28 Output terminal

Claims (10)

[Claims] 1. A head driver I in a control unit of a printer main body based on an anode voltage of a diode provided in a head driver IC of an ink jet printer.
A head driver IC temperature detecting device for an ink jet printer, which detects whether C temperature is higher or lower than a predetermined temperature, comprising: a temperature setting unit for setting a digital reference value corresponding to a reference temperature for temperature detection; The DA converter for converting the digital reference value of to the analog reference value and the anode voltage of the diode are compared with the analog reference value from the DA converter to determine whether the anode voltage of the diode is higher or lower than the analog reference value. A head driver IC temperature detection device for an ink jet printer, characterized in that each head driver IC includes a comparator that outputs a digital signal to the control unit of (1). 2. The ink jet printer according to claim 1, wherein the digital signals output from the comparators of the head driver ICs are output to the control unit of the printer body independently of each other. Head driver IC temperature detection device. 3. The head driver IC according to claim 1, further comprising an FET whose output is an open drain, to which a digital signal output from each comparator is input to each gate. A head driver IC temperature detecting device for the inkjet printer described. 4. The digital signal output from the open drain of the FET of each head driver IC is output to the control unit of the printer main body independently of each other. Head driver IC temperature detection device for the inkjet printer. 5. The digital signals output from the open drains of the FETs of the head driver ICs are wired and connected to each other and output to a control unit of the printer body by a single cable. The head driver IC temperature detecting device for an ink jet printer according to claim 3, characterized in that. 6. The head driver IC according to claim 1, further comprising a bipolar transistor having a base to which a digital signal output from each comparator is input and whose output is an open collector. 2. A head driver IC temperature detecting device for an ink jet printer according to item 2. 7. The digital signal output from the open collector of the bipolar transistor of each head driver IC is output to the control unit of the printer main body independently of each other. Head IC for inkjet printer
Temperature detection device. 8. The digital signals output from the open collectors of the bipolar transistors of the head driver ICs are wired and connected to each other and output to the control unit of the printer body by a single cable. The head driver IC temperature detecting device for an ink jet printer according to claim 6, characterized in that. 9. The temperature setting unit of each head driver IC,
9. The head driver IC temperature detection device for an ink jet printer according to claim 1, wherein the head driver IC temperature detection device is set independently corresponding to individual conditions such as a heat generation condition and a heat dissipation condition of the head driver IC. . 10. The temperature setting unit of each of the head driver ICs includes a digital data storage unit having a predetermined number of bits, and the digital reference value can be freely set within the range of the number of bits. Yes, claims 1 to 9
Head driver I of the inkjet printer described in 1.
C temperature detection device.