IC chip, print apparatus, and heat generation warning method

A printer (1) comprises a motor driver (34) for driving a carriage motor (20) and a paper feed motor (22). The motor driver (34) has a thermal shutdown circuit (43). If internal temperature T of the motor driver exceeds threshold value Ta, the thermal shutdown circuit shuts down the power of the motor driver. The motor driver has an internal temperature detection circuit (45). If the internal temperature T exceeds threshold value Tb (<Ta) before thermal shutdown processing operates, the internal temperature detection circuit outputs a HW signal. A CPU (29) executes heat generation stop processing based on the HW signal and controls the motor driver to stop the carriage motor and the paper feed motor for a predetermined time.

BACKGROUND OF THE INVENTION

This invention relates to an IC chip, a print apparatus, and a heat generation warning method.

A printer in a related art contains a motor driver for outputting a motor signal responsive to a control signal from a CPU to drive a carriage motor and a paper feed motor. The motor driver is implemented as a one-chip IC and a power supply voltage is supplied to one of a plurality of pins extending from a package. The motor driver is mounted on a board together with the CPU, memory, and a logic circuit.

This kind of motor driver has a thermal shutdown function to protect from heat generation. JP-A-6-225582, JP-A-8-501199, etc., discloses an example of a thermal shutdown circuit. If a carriage motor or a paper feed motor is over used and the internal temperature of the motor driver exceeds a threshold value (junction temperature), the thermal shutdown circuit operates for shutting down output of the motor driver. Accordingly, the carriage motor and the paper feed motor are stopped independently of the drive situation, and print processing and paper feed operation are forcibly terminated, thereby protecting the motor driver from heat generation.

However, in the protection method using the thermal shutdown function, the power of the motor driver is forcibly shut down at the shutdown time and thus the carriage motor and the paper feed motor are stopped independently of the print processing. Therefore, if the motor driver is cooled and is recovered from heat generation, it is impossible to resume the print processing at the shutdown point in time, and the print processing needs to be again performed from the beginning.

On the other hand, there is demand for reducing the cost of the motor driver. To meet the demand, the chip area may be lessened. However, if the chip area is lessened, the motor driver easily generates heat accordingly and the shutdown frequency is increased. If the shutdown frequency is thus increased, the print processing is forcibly terminated each time a shutdown occurs, interfering with smooth print processing. Thus, there is also a problem of incapability of lessening the chip area.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an IC chip, a print apparatus, and a heat generation warning method for making it possible to protect a driver circuit from heat generation and continuously execute predetermined processing operation if the driver circuit is protected from heat generation.

To the end, according to a first aspect of the invention, there is provided an IC chip for outputting a drive signal responsive to an external control signal for a driving drive unit, where in when the internal temperature of circuitry exceeds a first threshold value, output of the drive signal is shut down, the IC chip comprising a temperature detection unit for detecting the internal temperature of the circuitry of the IC chip; and a signal output unit for outputting a signal to stop the drive unit if the temperature detected by the temperature detection unit exceeds a second threshold value set to a lower temperature than the first threshold value.

According to the invention, the internal temperature of the circuitry of the IC chip is detected by the temperature detection unit and when the internal temperature exceeds the second threshold value, the signal output unit outputs a signal to stop the drive unit. Therefore, if the IC chip generates heat, the drive unit is once stopped before the internal temperature of the IC chip exceeds the first threshold value and output of the drive unit is shut down, so that the IC chip is protected from heat generation without using a method of shutting down output of the drive unit. Since the cooling method is a method of once stopping the drive unit, terminating each processing to execute cooling is avoided.

According to a second aspect of the invention, there is provided a print apparatus comprising a drive unit and a driver circuit for outputting a drive signal for driving the drive unit, wherein when internal temperature of the driver circuit exceeds a first threshold value, output of the drive signal is shut down, the print apparatus comprising a temperature detection unit for detecting the internal temperature of the driver circuit; and a control unit for controlling the driver circuit to stop the drive unit based on determination information as to whether or not the temperature detected by the temperature detection unit exceeds a second threshold value set to a lower temperature than the first threshold value.

According to the invention, the internal temperature of the driver circuit is detected by the temperature detection unit. The control unit performs processing based on the determination information as to whether or not the temperature detected by the temperature detection unit exceeds the second threshold value; for example, if the detected temperature exceeds the second threshold value, the control unit controls the driver circuit to stop the drive unit. Therefore, if the driver circuit generates heat, the driver circuit is controlled and the drive unit is stopped before the internal temperature of the driver circuit exceeds the first threshold value and output of the drive unit is shut down, so that the driver circuit is protected from heat generation without using a method of shutting down output of the drive unit.

According to a third aspect of the invention, in the second aspect, when the driver circuit is cooled as the drive unit is stopped and the detected temperature becomes equal to or less than the second threshold value, the control unit restarts driving the drive unit so as to continue processing at the stop point in time.

According to the third aspect of the invention, in addition to the function of the second aspect, when the driver circuit is cooled as the drive unit is stopped and the detected temperature becomes equal to or less than the second threshold value, the drive unit is restarted so as to continue the job at the point in time at which the stop state was entered, so that the processing interrupted as the drive unit was stopped can be continued.

According to a fourth aspect of the invention, in the second and third aspects, if the driver circuit is cooled as the drive unit is stopped and the detected temperature becomes equal to or less than the second threshold value, the control unit maintains the drive unit in the stop state for a predetermined time before restarting to drive the drive unit.

According to the fourth aspect of the invention, in addition to the function of the second third aspects of the invention, if the driver circuit is cooled and the detected temperature becomes equal to or less than the second threshold value, the drive unit is maintained in the stop state for the predetermined time, so that the cooling time of the driver circuit is prolonged and the driver circuit can be cooled sufficiently.

According to a fifth aspect of the invention, the print apparatus of the second to fourth aspects comprises a stop detection unit for determining whether or not the drive unit stops, wherein if the stop detection unit detects the drive unit stopping, the control unit determines whether or not the detected temperature exceeds the second threshold value.

According to the fifth aspect of the invention, in addition to the function of the second to fourth aspects of the invention, the stop detection unit determines whether or not the drive unit stops. If the stop detection unit detects the drive unit stopping, the control unit determines whether or not the detected temperature exceeds the second threshold value. Therefore, it is made possible to cool the driver circuit without interrupting the processing which needs to be continued using the drive unit as the drive source.

According to a sixth aspect of the invention, in the fifth aspect of the invention, the drive unit is a carriage motor for driving a carriage or a paper feed motor for moving paper, and when the carriage motor or the paper feed motor stops, the control unit determines whether or not the detected temperature exceeds the second threshold value.

According to the sixth aspect of the invention, in addition to the function of the fifth aspect of the invention, the stop detection unit determines whether or not the carriage motor or the paper feed motor stops. When the carriage motor or the paper feed motor stops, the control unit determines whether or not the detected temperature exceeds the second threshold value. If the detected temperature exceeds the second threshold value, the driver circuit is controlled and the drive unit is stopped. Accordingly, occurrence of print unevenness in the lateral direction of paper as the carriage motor is once stopped during the printing or occurrence of print unevenness in the longitudinal direction of paper as paper feed at a constant distance at a time is interrupted can be prevented.

According to a seventh aspect of the invention, in the second to sixth aspects of the invention, when the detected temperature exceeds the second threshold value, the control unit immediately controls the driver circuit to stop the drive unit.

According to the invention, in addition to the function of the second to sixth aspects of the invention, when the detected temperature exceeds the second threshold value, immediately the drive unit is stopped, so that when the driver circuit generates heat, immediately the driver circuit can be cooled.

According to an eighth aspect of the invention, the print apparatus of the second to seventh aspects comprises a notification unit, when the temperature detected by the temperature detection unit exceeds the second threshold value and the control unit stops the drive unit, for informing the user of the fact.

According to the eighth aspect of the invention, in addition to the function of the second to seventh aspects of the invention, when the detected temperature exceeds the second threshold value and the drive unit is stopped, the notification unit informs the user of the fact, so that it is made possible for the user to recognize that the processing is executed.

According to a ninth aspect of the invention, in the second to eighth aspects of the invention, the driver circuit is one IC chip comprising a temperature detection unit for detecting internal temperature of the IC chip, and a signal output unit for outputting a signal to stop the drive unit as determination information if the temperature detected by the temperature detection unit exceeds the second threshold value, and the control unit controls the driver circuit to stop the drive unit based on the signal output from the IC chip.

According to the ninth aspect of the invention, in addition to the function of the second to eighth aspects of the invention, the internal temperature of the IC chip is detected by the temperature detection unit and if the internal temperature exceeds the second threshold value, as the determination information, a signal to stop the drive unit is output from the signal output unit to the control unit. When inputting the signal, the control unit controls the IC chip to once stop the drive unit. By the way, if the area of the driver circuit (IC chip) is miniaturized, heat is easily generated and accordingly the internal temperature of the IC chip easily exceeds the first threshold value and output of the drive signal from the IC chip is shut down. However, before output of the drive signal is shut down, the IC chip is controlled to stop the drive unit, whereby the IC chip is cooled, so that shutting down of the drive signal output from the IC chip becomes hard to occur, and the substrate area can be miniaturized.

According to a tenth aspect of the invention, in the ninth aspect of the invention, the driver circuit comprises a regulator for supplying stable power to a predetermined circuit other than the driver circuit contained in the print apparatus.

According to the tenth aspect of the invention, in addition to the function of the ninth aspect of the invention, the driver circuit contains the regulator. By the way, if the driver circuit contains the regulator, when the internal temperature of the driver circuit exceeds the first threshold value and output of the drive signal from the driver circuit is shut down, output from the regulator is also shut down. However, before output of the drive signal is shut down, the driver circuit is controlled to stop the drive unit, whereby the driver circuit is cooled, so that shutting down of the drive signal output from the driver circuit becomes hard to occur, and the frequency of turning off the, power of the regulator can be lessened.

According to an eleventh aspect of the invention, in the ninth and tenth aspects of the invention, one driver circuit can drive a plurality of drive unit.

In this case, in addition to the function of the ninth aspect and tenth aspects of the invention, one driver circuit drives a plurality of drive unit.

According to a twelfth aspect of the invention, in the second to eleventh aspects of the invention, if the temperature detected by the temperature detection unit exceeds a third threshold value set to a lower temperature than the second threshold value, the control unit performs duty control of the driver circuit.

According to the twelfth aspect of the invention, in addition to the function of the second to eleventh aspect of the invention, the third threshold value is set as a lower temperature than the second threshold value and if the temperature detected by the temperature detection unit exceeds the third threshold value, duty control of the driver circuit is performed and heat generation of the driver circuit is suppressed. If the driver circuit generates heat, when the detected temperature exceeds the third threshold value at the preceding stage of arriving at the second threshold value, duty control is performed, so that the detected temperature becomes hard to arrive at the second threshold value, and the processing of stopping the drive unit can be suppressed as much as possible.

According to a thirteenth aspect of the invention, in the second to eleventh aspects of the invention, if the temperature detected by the temperature detection unit exceeds a third threshold value set to a lower temperature than the second threshold value, the control unit controls the driver circuit to change drive speed of the drive unit.

According to the thirteenth aspect of the invention, in addition to the function of the second to eleventh aspects of invention, the third threshold value is set as a lower temperature than the second threshold value and when the temperature detected by the temperature detection unit exceeds the third threshold value, if the driver circuit is controlled so as to decrease the drive speed of the drive unit, heat generation of the driver circuit is suppressed. If the driver circuit generates heat, when the detected temperature exceeds the third threshold value at the preceding stage of arriving at the second threshold value, the drive speed of the drive unit is changed so as to suppress heat generation of the driver circuit, so that the detected temperature becomes hard to arrive at the second threshold value, and the processing of stopping the drive unit can be suppressed as much as possible.

According to a fourteenth aspect of the invention, there is provided a heat generation warning method used with a print apparatus comprising drive unit and a driver circuit for outputting a drive signal for driving the drive unit, wherein when internal temperature of the driver circuit exceeds a first threshold value, output of the drive signal is shutdown, wherein a temperature detection unit detects the internal temperature of the driver circuit, and a control unit controls the driver circuit to stop the drive unit based on determination information as to whether or not the temperature detected by the temperature detection unit exceeds a second threshold value set to a lower temperature than the first threshold value.

According to the fourteenth aspect of the invention, the internal temperature of the driver circuit is detected by the temperature detection unit. The control unit performs processing based on the determination information as to whether or not the temperature detected by the temperature detection unit exceeds the second threshold value; for example, if the detected temperature exceeds the second threshold value, the control unit controls the driver circuit to stop the drive unit. Therefore, if the driver circuit generates heat, the driver circuit is controlled and the drive unit is stopped before the internal temperature of the driver circuit exceeds the first threshold value and output of the drive unit is shut down, so that the driver circuit is protected from heat generation without using a method of shutting down output of the drive unit. Since the cooling method is a method of once stopping the drive unit, terminating each processing to execute cooling is avoided.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now toFIGS. 1 to 5, there is shown a preferred embodiment of an IC chip, a print apparatus, and a heat generation warning method embodying the invention.

FIG. 2is a perspective view to show the appearance of a printer. An ink jet record apparatus as a print apparatus, which will be hereinafter referred to as printer,1performs print processing for record paper3set in a supply tray and places the record paper3completed in printing on a paper ejection tray5through a paper ejection port4for ejecting the paper. An operation panel6of the printer1is provided with switches7to9. When the printer1is powered on, the power switch7is pressed. To manually feed or eject the record paper3, the paper feed/ejection switch8is pressed. To manually perform the cleaning operation of forcibly sucking nozzles of a record head10(seeFIG. 3), the ink maintenance switch9is pressed.

The operation panel6is provided with lamps11to15implemented as LEDs. When the power of the printer1is on, the power lamp11goes on. When no record paper3exists at the paper feed operation time, the paper check lamp12goes on; when a paper jam occurs, the paper check lamp12blinks. The black ink end lamp13or the color ink end lamp14blinks when the ink remaining amount of the corresponding color becomes small; the ink end lamp13or14goes on when the ink runs out. When the internal temperature of the printer1becomes a predetermined temperature and heat generation stop processing is executed, the heat generation warning lamp15goes on.

FIG. 3is a perspective view to show the internal configuration of the printer1. The printer1comprises a carriage16. The carriage16is attached to an endless timing belt19placed on a drive pulley17and a driven pulley18. The timing belt19is driven by a carriage motor20, whereby the carriage19is reciprocated in a main scanning direction with the carriage19guided by a rail21. A paper feed motor22is installed in a lower corner of the printer1. As the paper feed motor22is driven, the record paper3on the supply tray2is fed in a subscanning direction. The carriage motor20and the paper feed motor22correspond to a drive unit.

The record head10is disposed on the lower side of the carriage16opposed to the record paper3, and ink cartridges for supplying ink to the record head10(in the embodiment, two types of black and color ink cartridges) are detachably mounted on the top of the carriage16. The record head10is formed with a plurality of nozzles (not shown). When print processing is executed, ink is ejected through the nozzles toward the record paper3at a predetermined timing.

A cap24capable of sealing the nozzles of the record head10is disposed at a home position of the carriage16(inFIG. 3, right end). When the carriage16is at the home position, the cap24has a mechanism for sealing the record head10as the carriage16itself pushes up the cap24. That is, when the carriage16is at the home position, automatically the record head10is capped.

A suction pump25for placing the internal space of the cap24under negative pressure when the cleaning operation is executed is connected to the cap24by a pump tube26. The suction pump25is connected to the paper feed motor22by a gear mechanism (not shown) and uses the paper feed motor22as a drive source. A wiping member27made of an elastic plate of rubber, etc., is disposed between a print area of the record head10and the home position. When the record head10goes to the print area, the wiping member27wipes the surface of the record head10.

FIG. 1is an electric block diagram of the printer1. The printer1comprises a control circuit board28on which a CPU29, ROM30, RAM31, EEPROM32, an I/F33, a motor driver34as a driver circuit (IC chip), and a head driver35are mounted. The members29to33are connected to each other by a main bus36. The printer1is connected to a host computer38by a cable37through the I/F33, and executes print processing based on print data transmitted from the host computer38. The CPU29executes various types of print operation such as print processing using the RAM31and the EEPROM32as memory areas according to a control program stored in the ROM30. The CPU29corresponds to a control unit and a stop detection unit.

The motor driver34is implemented as a one-chip IC, and power supply voltage +VDD is supplied thereto. The motor driver34has input connected to the CPU29and output connected to the carriage motor20and the paper feed motor22, and outputs a drive signal (motor signal) responsive to a control signal from the CPU29to the carriage motor20and the paper feed motor22for driving the motors20and22. The head driver35has input connected to the CPU29and output connected to the record head10, and outputs a drive signal (drive voltage) responsive to a control signal from the CPU29to the record head10for driving a piezoelectric vibrator39of the record head10for ejecting ink.

The motor driver34comprises a regulator40and two motor drive circuits4l and42. The regulator40outputs highly stable voltage +Vr, smoothed and regulated based on power supply voltage +VDD to the CPU29for use as the power supply to the CPU29. Based on a control signal from the CPU29, one motor drive circuit41drives the carriage motor20and the other motor drive circuit42drives the paper feed motor22.

The motor driver34contains a thermal shutdown circuit43. The thermal shutdown circuit43is implemented as a switch circuit for switching the connection state depending on the temperature. When internal temperature T exceeds threshold value Ta, the thermal shutdown circuit43outputs a shutdown signal (SD signal) to the regulator40and the motor drive circuits41and42. At this time, the regulator40and the motor drive circuits41and42are disconnected from the power supply voltage +VDD, and the motor driver34is powered off. The carriage motor20and the paper feed motor22are stopped independently of the drive situation, and the print processing and paper feed operation are forcibly terminated. The power of the regulator40is also turned off.

The motor driver34contains an internal temperature detection circuit45. The internal temperature detection circuit45is also implemented as a switch circuit for switching the connection state depending on the temperature, and is connected to a connection pin46extended from the package of the motor driver34. The internal temperature detection circuit45has a temperature detector47as a temperature detection unit and a signal output section48as a signal output unit. The temperature detector47detects the internal temperature (detection temperature) T of the motor driver34. When the internal temperature T exceeds threshold value Tb (<Ta), the signal output section48outputs a heat generation warning signal (HW signal) to the CPU29through the connection pin46.

The threshold value Ta is set to a value in the range of T3to T4and the threshold value Tb is set to a value in the range of T1to T2(T1<T2<T3<T4) as shown in the relation inFIG. 5. That is, the threshold value Ta is a temperature value before the motor driver34is destroyed because of heat generation, and is set to a value in the range of T3to T4depending on the specifications. On the other hand, the threshold value Tb is a temperature value occurring in the motor driver34in a special pattern wherein the use condition of the motor deriver34is severe, namely, when print processing wherein the carriage16is often accelerated and decelerated or the paper feed amount is large is performed; the value is set in the range of T1to T2in response to the use condition.

During print processing or paper feed processing, when the carriage16is position at an end in the move direction, when the carriage motor20or the paper feed motor22stops, etc., the CPU29determines whether or not heat generation stop is to be applied. That is, the CPU29determines whether or not an HW signal is output from the internal temperature detection circuit45based on stop of the carriage motor20or the paper feed motor22as a trigger. If the internal temperature T of the motor driver34exceeds the threshold value Tb and the HW signal is output, the CPU29sets a heat generation warning flag F in the RAM31to ON and controls the motor driver34to stop both the carriage motor20or the paper feed motor22in a predetermined time. The CPU29turns on the heat generation warning lamp15during the heat generation stop mode.

In the heat generation stop mode, the CPU29monitors output of the HW signal at all times. When the internal temperature T of the motor driver34falls below the threshold value Tb and the HW signal is not output, the CPU29sets the heat generation warning flag F stored in the RAM31to OFF and sets a timer49. When the timer49times out, the CPU29releases the heat generation stop and controls the motor driver34to restart driving the carriage motor20or the paper feed motor22. At this time, the CPU29turns off the heat generation warning lamp15in addition to releasing the heat generation stop mode.

Next, processing executed by the CPU29in the heat generation stop mode will be discussed with reference to a flow chart ofFIG. 4. The processing is started using as a trigger, a signal output when at least either of the carriage motor20and the paper feed motor22stops, and is repeated every predetermined period (for example, several msec).

First, at step100(simply, S100), an HW signal is checked. That is, whether or not an HW signal is output from the internal temperature detection circuit45is checked.

At S101, whether or not heat generation warning is to be produced is determined. That is, when the internal temperature T of the motor driver34exceeds the threshold value Tb and an HW signal is input from the internal temperature detection circuit45, control goes to S102. On the other hand, if the internal temperature T is the threshold value Tb or less and an HW signal is not input from the internal temperature detection circuit45, control goes to S104.

At S102, heat generation stop is started. That is, the motor driver34is not driven to stop both the carriage motor20and the paper feed motor22. At this time, the heat generation warning lamp15is also turned on.

At S103, the heat generation warning flag F is set in the RAM31. After the heat generation warning flag F is set, control returns to S100and if it is again determined at S101that an HW signal is input, the heat generation stop node is maintained and the heat generation warning flag F is left set.

At S104, whether or not the heat generation warning flag F is set is determined, If the heat generation warning flag F is set, control goes to S105; otherwise, control goes to S107.

At S106, the heat generation warning flag F stored in the RAM31is set to OFF. After the heat generation warning flag F is set to OFF, control returns to S104.

At S107, the timer value of the timer49is decremented by one.

At S108, whether or not the timer value of the timer49becomes 0 is determined. That is, whether or not the timer49times out is determined, If the timer value is 0, control goes to S109; if the timer value is not 0, control returns to S107and the step of decrementing the timer value by one is repeated.

At S109, the heat generation stop mode is released. That is, a control signal is sent to the motor driver34for releasing the stop state of the carriage motor20and the paper feed motor22and restarting driving the motors20and22.

By the way, when print processing is executed in the printer1, the motor driver34generates heat in response to driving of the carriage motor20and the paper feed motor22, and the internal temperature T rises gradually. Particularly, when print processing wherein the carriage16is often accelerated and decelerated or paper feed processing of the record paper3is performed for a long time, heat generation becomes noticeable. In the embodiment, when the carriage motor20or the paper feed motor22stops, whether or not heat generation stop is to be applied is determined. If the internal temperature T exceeds the threshold value Tb and an HW signal is output from the motor driver34, the heat generation stop processing is performed. Accordingly, print processing or paper feed processing is once stopped, the stop time or the motors20and22is increased, and the motor driver34is cooled

The motor driver34is cooled until the timer49of the CPU.49times out after the internal temperature T becomes the threshold value Tb or less and the HW signal is not output from the motor driver34. After the timer49times out, the carriage motor20and the paper feed motor22are again driven, and the print processing or paper feed processing once stopped is restarted.

Further, if the internal temperature T of the motor driver34rises excessively and exceeds the threshold value Ta higher than the threshold value Tb, thermal shutdown processing is executed. Then, output of the motor driver34is shut down, whereby the carriage motor20and the paper teed motor22are stopped for forcibly terminating the print processing and paper feed processing, and the motor driver34is protected from destruction caused by heat generation. The thermal shutdown processing is executed according to a different flow from that of the heat generation stop processing, and the CPU29does not directly see the thermal shut down processing and determines whether or not the thermal shutdown processing is performed from another motion.

Thus, in the thermal shutdown processing, as output of the motor driver34is shutdown, the print processing is forcibly terminated. Thus, although heat generation can be suppressed, the later print processing cannot be continued. However, if the internal temperature T of the motor driver34exceeds the threshold value Tb before the thermal shutdown function is operated, the motors20and22are stopped and heat generation stop for cooling the motor driver34is executed, so that the normal print processing can be continued while the motor driver34is protected from heat generation.

The embodiment can provide the following advantages:

(1) The threshold value Tb for starting heat generation stop is set as a temperature lower than the threshold value Ta for executing the thermal shutdown processing. When the internal temperature T of the motor driver34exceeds the threshold value Tb, the carriage motor20and the paper feed motor22are once stopped and the motor driver34is cooled as the heat generation stop processing. When heat generation of the motor driver34is released, the carriage motor20and the paper feed motor22are again driven, and the print processing and paper feed processing once stopped are restarted. Therefore, the motor driver34can be protected from heat generation and the cooling method is a method of once stopping the motors20and22, so that the print processing and paper feed processing can be executed continuously.

(2) Since the heat generation stop processing is performed for cooling the motor driver34before the thermal shutdown processing is performed, the internal temperature T of the motor driver34becomes hard to exceed the threshold value Ta and the thermal shutdown processing can be made hard to occur. Accordingly, if the chip area of the motor driver34is lessened, the motor driver34is cooled by the heat generation stop processing before it is shut down, so that the thermal shutdown processing does not frequently occur and the chip area of the motor driver34can be miniaturized.

(3) When output of the HW signal stops from the motor driver34, the timer49is set and the carriage motor20and the paper feed motor22are stopped for cooling the motor driver34until the timer49times out. Therefore, as compared with the case where driving the motors20and22is restarted when output of the HW signal stops, the cooling time when the motor driver34is cooled is prolonged and the motor driver34can be cooled sufficiently.

(4) If the heat generation stop processing is executed and the carriage16is stopped at an intermediate point in the move path while one-pass printing is being performed, if the printing is restarted at the point, print unevenness occurs. In the embodiment, however, when the carriage16is positioned at the end in the move direction and the carriage motor20stops, whether or not the heat generation stop processing is to be executed is determined and if the heat generation stop processing is to be executed, the stop time at the position is taken long. Thus, the carriage does not stop during one-pass printing.

(5) Since the printer1is provided with the heat generation warning lamp15and the heat generation warning lamp15is lighted during execution of heat generation stop, the user can be notified that heat generation stop is executed.

(6) In the motor driver34containing the regulator40for supplying power to the CPU29, it is not preferred that the thermal shutdown processing is executed for turning off the power of the motor driver34. However, since the heat generation stop processing is performed for cooling the motor driver34before the thermal shutdown processing is performed, the thermal shutdown processing becomes hard to occur, and various problems occurring when the motor driver34containing the regulator is shut down can be solved. When the heat generation stop processing is performed, the regulator40is cooled and thus can be protected from heat generation.

(7) Since the motor driver34drives the carriage motor20and the paper feed motor22, one chip can drive a plurality of motors.

The invention is not limited to the specific embodiment and can be modified to the following:

The invention is not limited to the configuration wherein the internal temperature detection circuit45implemented as a switch circuit is used and the CPU29performs the heat generation stop processing based on the HW signal output from the internal temperature detection circuit45. For example, the motor driver34is provided with a temperature sensor as a temperature detection unit and the CPU29monitors the detection value from the temperature sensor and if the internal temperature T of the motor driver34found based on the detection value exceeds the threshold value Tb, the heat generation stop processing may be executed.

The determination as to whether or not the internal temperature T of the motor driver34exceeds the threshold value Tb is not limited to the determination executed based on stop of the carriage motor20or the paper feed motor22as a trigger. For example, the CPU29monitors the HW signal from the internal temperature detection circuit45at all times and when the internal temperature T exceeds the threshold value Tb, the carriage motor20and the paper feed motor22may be stopped immediately. In this case, heat generation of the motor driver34caused by driving the carriage motor20and the paper feed motor22can be minimized.

As a method of stopping the paper feed motor22in the heat generation stop processing, the paper feed motor22may be stopped immediately. For example, when the HW signal is input from the internal temperature detection circuit45, if paper feed processing is executed, the CPU29calculates the remaining paper feed time and if the paper feed time exceeds a predetermined threshold value, the CPU29immediately stops the paper feed motor22. In this case, heat generation of the motor driver34caused by driving the paper feed motor22and the paper feed motor22can be minimized.

The thermal shutdown circuit43is not limited to the circuit for turning off also the power of the regulator40. For example, a thermal shutdown circuit50for turning off the power of only the motor drive circuits41and42may be provided, as shown inFIG. 6.

The invention is not limited to the mode wherein when output of the HW signal from the internal temperature detection circuit45stops, the timer49is set and when the timer9times out, driving the carriage motor20and the paper feed motor22is restarted. That is, when output of the HW signal from the internal temperature detection circuit45stops, driving the motors20and22may be restarted.

The heat generation stop processing is not limited to processing where in the heat generation warning lamp15is lighted, thereby notifying the user that the heat generation stop processing is being executed, and may be a configuration wherein the user is not notified that the heat generation stop processing is being executed. The method is not limited to use of the heat generation warning lamp15to provide visual information for the user; for example, a loudspeaker, etc., may be used to provide auditory information for the user when the user is notified that the heat generation stop processing is being executed.

The regulator40contained in the motor driver34may or may not be shut down at the thermal shutdown processing time. The motor driver34need not necessarily contain the regulator40; the regulator may be omitted.

The motor driver34is not limited to that for driving both the carriage motor20and the paper feed motor22; one may drive the carriage motor20and one may drive the paper feed motor22. One motor driver34may drive three or more motors; it may drive any other motor installed in the printer1, such as a paper feed motor for driving a paper feed roller independently, in addition to the carriage motor20and the paper feed motor22.

The driver circuit is not limited to the motor driver34for driving motors of the carriage motor20, the paper feed motor22, etc.,; for example, it may be any other drive circuit such as the head driver35. At this time, the piezoelectric vibrator39corresponds to a drive unit.

Using the motor driver34, whether or not heat generation stop is to be applied only when the carriage motor20stops may be determined. In constant, whether or not heat generation stop is to be applied only when the paper feed motor22stops may be determined.

The heat generation suppression processing of the motor driver34is not limited to the method of once stopping the carriage motor20and the paper feed motor22and prolonging the stop time (heat generation stop processing). For example, the following method may be used: Threshold value Tc (third threshold value) is set as a temperature lower than the threshold value Tb and when the internal temperature T exceeds the threshold value Tc, duty control of the motor driver34is performed for suppressing output of the carriage motor20and the paper feed motor22. The duty control refers to control of changing the duty ratio of voltage (current) applied to the motor20,22and dropping output of the motor20,22by a predetermined value.

In this case, if the motor driver34generates heat, the operating condition of the motor driver34is suppressed under the duty control at the preceding stage of the internal temperature T going to Tb and accordingly heat generation of the motor driver34can be suppressed. As a result, the frequency at which the internal temperature T reaches the threshold value Tb lessens and the occurrence frequency of the heat generation stop processing can be lessened. At this time, if the internal. temperature T continues to exceed the threshold value Tc for a predetermined time, the duty ratio may be further lowered for suppressing the temperature rise.

The heat generation suppression processing under the duty control may be applied to the head driver35rather than the motor driver34, and duty control of the head driver35may be performed, thereby lowering the duty ratio of voltage applied to the piezoelectric vibrator39.

To set the threshold value Tc and perform duty control, threshold value Td (fourth threshold value) may be set between the threshold values Tb and Tc and such processing of placing the internal temperature T between the threshold values Tc and Td may be performed. That is, if the internal temperature T exceeds the threshold value Tc, the duty control is started and when the temperature rise further continues and the internal temperature T exceeds the threshold value Td, the duty ratio is lowered and the cooling degree of the motor driver34is raised. In this case, the internal temperature T becomes still harder to reach the threshold value Tb and the occurrence frequency of the heat generation stop processing can be still more suppressed.

To perform the duty control at the preceding stage of performing the heat generation stop processing, the number of threshold values is not limited to one (use of the threshold value Tc) or two (use of the threshold values Tc and Td). That is, the number of threshold values to perform the duty control may be three or more and the duty ratio may be set for each threshold value area for effectively suppressing heat generation of the motor driver34.

The heat generation suppression processing of the motor driver34is not limited to the heat generation stop processing or the duty control. For example, the following method may be used: Threshold value Tc (third threshold value) is set as a temperature lower than the threshold value Tb and when the internal temperature T exceeds the threshold value Tc, the motor driver34is controlled for suppressing the drive speed of the carriage motor20and the paper feed motor22. In this case, if the motor driver34generates heat, the drive speed of the motor20,22is lowered at the preceding stage of the internal temperature T going to Tb, whereby the operating state of the motor driver34is suppressed and accordingly heat generation of the motor driver34can be suppressed. Further, as a result, the frequency at which the internal temperature T reaches the threshold value Tb lessens and the occurrence frequency of the heat generation stop processing can be lessened.

The print apparatus is not limited to the ink jet printer1; for example, it may be any other type of printer such as a color printer, a laser beam printer, or a dot impact printer, and heat generation stop processing of the motor driver installed in any of the printers may be performed. The heat generation stop processing may be adopted for the motor driver for driving a motor installed in a scanner. The heat generation stop processing in the embodiment maybe adopted not only for printers, scanners, etc., but also for any other OA machine.

The technical ideas that can be understood from the embodiment and the modifications as well as the advantages thereof is as follows:

Technical Idea 1

A regulator is provided for supplying stable power to a predetermined circuit other than the IC chip. In this case, stable power can be supplied to the predetermined circuit from the IC chip. ps Technical Idea 2

The second threshold value is set to a temperature value occurring in the driver circuit when the drive unit is driven under severe use condition.

Technical Idea 3

If the temperature detected by the temperature detection unit exceeds the second threshold value, the control unit controls the driver circuit to stop the drive unit.

Technical Idea 4

When the driver circuit is cooled as the drive unit is stopped and the detected temperature becomes equal to or less than the second threshold value, the control unit restarts driving the drive unit so as to continue processing at the stop point in time.

Technical Idea 5

In the technical idea 4, if the driver circuit is cooled as the drive unit is stopped and the detected temperature becomes equal to or less than the second threshold value, the control unit maintains the drive unit in the stop state for a predetermined time before restarting to drive the drive unit.

Technical Idea 6

In the technical ideas 4 and 5, the print apparatus comprises a stop detection unit for determining whether or not the drive unit stops, wherein if the stop detection unit detects the drive unit stopping, the control unit determines whether or not the detected temperature exceeds the second threshold value.

Technical Idea 7

In the technical ideas 4 to 5, the drive unit is a carriage motor for driving a carriage or a paper feed motor for moving paper, and when the carriage motor or the paper feed motor stops, the control unit determines whether or not the detected temperature exceeds the second threshold value.

Technical Idea 8

In the technical ideas 4 to 7, the print apparatus comprises a notification unit, when the temperature detected by the temperature detection unit exceeds the second threshold value and the control unit stops the drive unit, for informing the user of the fact. In this case, similar advantages to those in claim8can be provided.

Technical Idea 9

In the technical ideas 4 to 8, the driver circuit is one IC chip comprising a temperature detection unit for detecting internal temperature of the IC chip, and a signal output unit for outputting a signal to stop the drive unit as a determination information if the temperature detected by the temperature detection unit exceeds the second threshold value, and the control unit controls the driver circuit to stop the drive unit based on the signal output from the IC chip.

Technical Idea 10

In the technical ideas 4 to 9, if the temperature detected by the temperature detection unit exceeds a third threshold value set to a lower temperature than the second threshold value, the control unit performs duty control of the driver circuit.

Technical Idea 11

In the technical philosophy 4 to 9, if the temperature detected by the temperature detection unit exceeds a third threshold value set to a lower temperature than the second threshold value, the control unit controls the driver circuit to change drive speed of the drive unit.

Technical Idea 12

If the temperature detected by the temperature detection unit exceeds the second threshold value, the control unit controls the driver circuit to stop the drive unit.

As described above in detail, according to the invention, the driver circuit can be protected from heat generation and in addition, if the driver circuit is protected from heat generation, predetermined processing operation can be continuously executed.