JPH09322380A - Abnormality detector of power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the fault of the control element of a power supply circuit for a load (for example, temperature adjusting sub-heater and the fault of the load itself. SOLUTION: A power supply circuit has a plurality of loads SUBHY-SUBHK, power control elements TR2-TR5 for controlling the power of the loads, a power supply element TR1, which is connected to the common connecting terminal of load control elements, and controllers 1101-1109, which can independently control the power control elements and the power supply element. An abnormality detecting circuit has a resistor 1111 and capacitor 1112, which are connected between the above described common terminal and GND in series, and voltage dividing resistors 1113 and 1114, which observe the change in voltage across both ends of the capacitor. The voltage across both ends of the capacitor is monitored by a microcomputer through an Error terminal. By measuring the time change of the voltage in synchronization with the ON/OFF control of the power control element, the abnormality of the power control element and the abnormality of the load are detected, and the device is stopped at the time of abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for a power supply circuit, for example, in a recording head of an ink jet recording system which ejects ink by energy when heating and boiling ink, electric power is supplied to a heating means such as a heater. The present invention relates to a technique for detecting an abnormality in a power supply circuit that supplies power.

The present invention is not limited to such heat generating means as a load supplied with electric power from the electric power supply circuit, but may be a lamp, a semiconductor laser, a light emitting diode or an electro-optical conversion element such as electroluminescence, or an electrostrictive oscillator. It can also be applied to electrodynamic conversion elements such as solenoids and solenoids, and electromagnetism conversion elements such as magnetic heads and chargers.

[0003]

2. Description of the Related Art Conventionally, in a recording head of a type that ejects ink with energy when heating and boiling the ink, if the temperature of the ink within the noise ejecting the ink and the temperature of the heater base are constant. It is known that the amount of ejected ink is stable and the occurrence of non-ejection and uneven density can be suppressed. Therefore, JP-A-58-
As proposed in JP-A-220757, a sub-heater for temperature adjustment is placed in the vicinity of the ink ejection heater or on the heater base substrate, and a temperature sensor for detecting the temperature is also placed in the vicinity of the ink ejection heater. Some have been equipped with a sub-heater control circuit that controls power supply to the sub-heater according to the detected temperature.

As means for detecting whether or not the controlled electric power is normally supplied to the sub-heater,
(1) As shown in FIG. 13, the power control element 131, the sub-heater board 132, and the current detection resistor 133 are connected in series, and the voltage across the resistor 133 (ErrorY, Error
(2) As shown in FIG. 14,
A method is conceivable in which the power control element 141, the sub-heater board 142, and the primary winding 143 of the current transformer for current detection are connected in series, and the determination is made from the output voltage (Error) of the secondary winding 144 of the current transformer. Came.

Further, in order to suppress an abnormal temperature rise of the recording head due to an abnormality of the sub heater control circuit, (3) as shown in FIG. 4, temperature detecting elements 109a and 109b are placed on the heater board of the recording head unit 1. , If a microcomputer connected to the temperature detecting element detects the temperature of the heater board through the analog input port and detects an abnormal temperature, the power supply unit that outputs the applied voltage (+ 19V) is turned off. , Was used to cut off the abnormality from the beginning.

[0006]

However, (1)
In the circuit as shown in FIG. 13 of the conventional example, there are problems that the power consumption by the current detecting resistor is a problem and that the voltage drop is not constant due to the characteristics of the load.

(2) In the circuit as shown in FIG. 14 of the conventional example, control is performed when a short circuit failure occurs in the cable connecting the control circuit section and the recording head section and the connector section, or when the sub heater element itself has a short circuit failure. Overcurrent flows through the transistor, causing thermal breakdown, resulting in a short-circuit failure mode. When such an abnormal state occurs, the recording head cannot perform normal printing, so users and service personnel
I think that the recording head is abnormal and replace it with a new recording head, and I mistake that repair is completed. However,
At this time, in reality, the transistor of the control circuit section has a short-circuit failure, so that power is constantly supplied to the sub-heater, and the temperature of the recording head section rises steadily, eventually resulting in destruction. Therefore, (3) conventionally, the temperature of the heater board of the recording head unit is monitored to prevent the recording head from being destroyed. However, when a rapid temperature rise occurs, the responsiveness of the temperature detecting element is increased. However, there remains a problem that it cannot be dealt with.

The present invention has been made to solve the above-mentioned problems, and the purpose thereof is to destroy the power control element which may occur at the time of a short circuit failure of a load such as a sub-heater, and to record after replacement. The purpose is to detect the secondary destruction of a device such as a head in advance and prevent a failure due to these destructions.

[0009]

In order to achieve the above object, the present invention provides a test mode for determining a short circuit fault of a load such as a sub-heater and a short circuit fault of a power control element (for example, a transistor). In order to minimize the power applied to the load in this test mode, a sequence to be performed at the time of turning on is provided, and power is supplied from an independent capacitor, and the time change of the voltage across the capacitor is observed to supply power. Detects circuit abnormalities and prevents breakage failures.

More specifically, the present invention includes a plurality of loads,
A plurality of power control elements for controlling the power of the load, at least one power supply element connected to the load and a common connection terminal other than the GND terminal, and the power control element and the power supply element can be independently controlled Control element, a resistor and a capacitor connected in series between the common connection terminal and the GND potential, and an abnormality detection for detecting an abnormality of the power supply circuit by observing a change in voltage across the capacitor And means.

In a preferred form, the abnormality detecting means is
A voltage dividing resistor connected to both ends of the capacitor, and the power control element and the power supply element are sequentially turned on / off independently via the control element to sequentially turn on / off the capacitor to obtain the voltage dividing resistor. By observing the temporal change of the both-end voltage in synchronism with ON / OFF control of the power control element, there is provided control means for detecting abnormality of each of the power control element, the power supply element and the load.

Further, preferably, when the control means detects an abnormality in at least one of the power control element, the power supply element, and the load, it stops the main body device including the load. Further, when the control means detects an abnormality in at least one of the power control element, the power supply element, and the load, the control means displays the fact that the abnormality is detected on the display means.

As an embodiment of the present invention, the load is an electrothermal conversion element, or the load is an electro-optical conversion element, the load is an electrodynamic conversion element, and the load is an electrical conversion element. It may be a magnetic conversion element.

Further, as another aspect of the present invention, a bridge circuit including a plurality of power control elements for controlling the power of the load, a control element capable of independently controlling the power control element, and the bridge circuit. A resistor and a capacitor connected in series between one side of the load connected to the midpoint and the GND potential, and an abnormality detection for detecting an abnormality of the power supply circuit by observing a change in voltage across the capacitor And means.

In this case, as a preferred mode, the abnormality detecting means controls ON / OFF of the voltage dividing resistors connected to both ends of the capacitor and the power control element through the control element independently and sequentially. A control means for detecting an abnormality of the power control element by observing a temporal change in the voltage across the capacitor obtained from the voltage dividing resistor in synchronization with ON / OFF control of the power control element. Have.
Then, when the control means detects an abnormality in the power control element, the control means displays the fact that the abnormality is detected on the display means, and stops the main body device including the load. The load may be a DC motor.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing an ink jet recording apparatus to which the present invention is applicable, and FIG. 2 is a diagram showing the carriage shown in FIG. 1 in detail. Where 3
The carriage unit shown by is built in the recording head unit 1 in which a plurality of recording heads are integrated inside the recording head fixing lever 4 which can be freely opened and closed, and the four color ink tanks 2K are provided.
(Black), 2C (cyan), 2M (magenta), 2
It is equipped with Y (yellow). Ink of different color is ejected from each of these recording heads, and a color image is formed on a recording medium (paper, cloth, etc.) by mixing these ink droplets.
The print data is transmitted from the image processing control device (not shown) of the printer body to the recording head through the flexible printed circuit board 8.

The print heads in the print head unit 1 are arranged in the order of 1K (black), 1C (cyan), 1M (magenta), and 1Y (yellow), and ink is ejected in this order in forward scanning. For example, red (hereinafter,
When printing R), first, magenta (hereinafter,
M) lands on the recording medium, and then yellow (hereinafter, Y) lands on the M dot and appears as an R dot.

Similarly, in the case of green (hereinafter, G), cyan (hereinafter, C) and Y are landed in that order, and in the case of blue (hereinafter, B), landed in C and M, respectively. To form the color of. In this example, the recording head ejects an ink droplet from the ejection port by causing a state change in the ink by using thermal energy.

The carriage 3 (carriage unit)
Is driven by a carriage motor (not shown) via a timing belt 7 to move on the guide shafts 5, 6. Further, the carriage 3 is provided with a position detecting means (not shown), and the scanning speed and the print position of the carriage 3 are detected by using the output of the position detecting means so as to control the movement in the main scanning direction. Has become. The recording is performed during the main scanning operation, the recording is performed by forming band-shaped dots on the recording medium (for example, the paper) 10, and the paper feeding in the sub scanning direction is performed by a platen driven by a paper feeding motor (not shown). This is done by feeding the recording medium 10 by the roller 9. That is, the recording operation is performed when the recording medium 10 moves in the direction of the arrow a in FIG. 1 and reaches the recording position.

FIG. 2 shows a state in which the recording head fixing lever 4 of the carriage 3 is in an open state. A terminal pad 13 is provided on the upper surface of the recording head unit 1 and the recording head fixing lever 4 is provided. When closed, electrical contact is made between the terminals 14 provided on the flexible printed circuit board 8 and the terminal pads 13 described above, and it becomes possible to control the recording heads provided in the recording head unit 1. .

FIG. 3 shows the electrical construction of the ink jet recording apparatus shown in FIG. The print head unit 1 includes a plurality of nozzle (ejection port) rows, an electrothermal converter (heater) provided corresponding to each nozzle, a heater driving logic circuit, a temperature detection element, a temperature adjustment sub-heater, and a print head specific This is a unit in which four recording heads (1K, 1C, 1M, 1Y) having information are arranged and integrated, and signals from the image signal processing device 11 on the main body side are transmitted via the flexible printed circuit board 8 to the connectors 13 and 14. Connected.

FIG. 4 shows a circuit configuration of each of the recording heads described above. The recording heads 1K, 1C, 1M and 1Y all have the same structure.

The discharge heater 101 includes heaters 1 to 6
There are 64 up to 4, and the driving transistor 102 and the AND gate 103 are connected to each of them. The ejection signals D1 to D64, the recording block control signals block 1 to block 8 and the ejection permission signal HENB are input to the AND gate 103.

As the ejection signals D1 to D64, the IDATA signal 112 which is recording data is converted into the clock signal (DCLK) 1
It is a signal held in the 64-bit latch register 106 in response to a latch signal (LTCLK) 115 that is taken into the 64-bit shift register 105 that shifts by 1 bit in synchronization with 13 and is transferred at the time of transferring 64 bits. Signal (RESET) after the end of discharge
At 114, it is cleared to 0.

Recording block control signals block 1 to bl
ock 8 is 3-bit BENB1, BENB2, BENB3 for designating the drive block sent from the main unit.
The signal 111 of 1 is decoded by the decoder 104 and distributed to the 8-bit signal line to generate an enable signal for 8 blocks (1 block corresponds to 8 nozzles).

The ejection permission signal (HENB) 110 is an ejection control signal for the entire recording head for one color, and controls the recording pulse width that determines the drive time of the ejection heater 101.

The recording heads (1K, 1C, 1M, 1
Y) is provided with a dummy resistor 108 for detecting the resistance value of the heater 101 (that is, for detecting the electric power of the heater), and a signal line connected to this dummy resistor 108 is connected to a constant current circuit (illustrated). No) to measure the voltage to control the power of the ejection head 101.

The recording head has diodes 109a, which serve as temperature sensors for controlling the ink temperature to be constant.
109b are arranged at both ends of the discharge heater 101.
Further, a temperature adjusting sub-heater 107 is arranged as a heating means, and the image signal processing device 11 on the main body side (see FIG. 3).
Performs temperature adjustment control for energizing the temperature adjustment sub-heater 107 according to the outputs of the diodes 109a and 109b.

FIG. 5 is an exploded perspective view showing the structure for one color of the recording head described above. The circuit shown in FIG. 4 is formed on the substrate (heater board) 100 made of a silicon semiconductor by the film forming technique. Has been formed. Discharge heater 10 of FIG.
The heat generated by No. 1 causes film boiling in the ink, and bubbles are generated by this to eject the ink. Wiring board 2
00 is composed of a wire bonding pad corresponding to the wiring of the heater board 100, a pad for receiving an electric signal from the main body device, and a pattern wiring for connecting the pads. The grooved top plate 1300 has a partition wall for dividing a plurality of ink paths, a groove for forming a common liquid chamber for storing ink to be supplied to each ink path, and the like, and is supplied from an ink tank. An ink supply port 1500 that receives ink and is introduced into the common liquid chamber is integrally provided with an orifice plate 400 that has a plurality of ejection ports corresponding to the respective ink paths.

The support 300 supports the back surface of the wiring board 200 on a flat surface and is made of metal such as aluminum. The pressing spring 500 is M-shaped and presses a portion of the top plate corresponding to the common liquid chamber with a light pressure at the center of the M-shape, and the front drooping portion 501 concentrates a portion corresponding to the ink path with a linear pressure. Press.

The ink supply path member 600 forms an ink introducing pipe 1600 which is continuous with the ink supplying pipe 2200 as a cantilevered beam whose side is fixed on the ink supplying pipe 2200 side, and the fixed side of the ink introducing pipe 1600 and the ink supplying pipe 220.
A sealing ball 602 for ensuring a capillary phenomenon with 0 is inserted therein. Ink supply pipe 220
A filter 700 is provided at the end portion of the tank side 0.

FIG. 6 is an exploded perspective view showing the structure of the recording head unit 1 in which a plurality of recording heads are integrated.
As shown in the figure, in this example, four recording heads (IJ
(U) is adhesively fixed to the unit frame 4000, and the recording heads are replaced for each unit, so that the mutual positional relationship of the four recording heads does not shift due to the mounting operation during replacement. I am doing it.

The upper housing 4506 and the side housing 4006 are fixed to the unit frame 4000, respectively.
In fixing the upper housing 4506, a pair of pins 4504 (two places including the back side) provided therein are inserted into holes 4011 provided in the upper end surface of the outer wall plate 4001 of the unit frame 4000. By doing so, the upper housing 4506 is positioned when fixed, and the projections on the latch plates 4505 formed at both ends of the upper housing are elastically biased by the latch plates 4505 in the recesses 4010 formed in the outer wall plate 4001. It is fixed by being hooked with.
The side housing 4006 is fixed to the unit frame by using the pair of latch plates 4508 of the side housing 4006 and the recess 4007 of the unit frame 4000.
Same as 506.

A plurality of pads 4502 as electric contacts on the recording head IJU side are provided in a portion corresponding to the outer surface of the upper housing 4506, and each of the pads 4502 extends to the back surface side of the upper housing 4506.
01 is connected. Each terminal 4501 makes contact with a corresponding connection pad on the substrate of the recording head when the upper housing 4506 is fixed to the unit frame 4000.

The side housing 4006 has a hole 4 through which the ink supply tube 2200 of the recording head IJU is inserted.
009 is formed.

The reason for using the structure of the recording head unit as described above is that the defective recording head unit can be easily replaced by a user or a service person. This means that the number of contacts increases. This caused problems with the contacts (short circuit and open failure that did not close the contacts). In addition, since a small recording head unit is formed, a large number of comb-teeth-shaped terminals 4501 are arranged as shown in FIG. 6, and when a large impact (for example, dropping the recording head unit) is applied, these terminals are arranged. There is a great possibility that they will come into contact with each other.

Therefore, it is possible to detect these abnormal states,
The abnormality detection means according to the present invention will be described below with reference to FIGS.
Will be described with reference to the drawings.

In FIG. 7, the circuit surrounded by the thick frame 11 shows the sub-heater control circuit, which is particularly composed of the sub-heater drive circuit and the abnormality detection circuit, in the image signal processing device 11 of FIG. The circuit surrounded by the frame 1 is shown in FIG.
4 shows the connection state of the sub-heaters 107 of each of the four-color heads in the recording head unit 1. When performing temperature control by the normal sub-heater 107,
A signal line (signal line name: V) of a microcomputer (not shown) connected to the interface transistor 1101.
Mon) is set to the “Hi” (high level) state, whereby the power supply transistor 1102 (hereinafter, TR1) is turned on.
The N state is entered, and the sub heater applied voltage VM volt is set to TR1.
It will be possible to run from the collector of. In this state, for example, when power is supplied to the yellow sub-heater (hereinafter, SUBHY), the interface transistor 11
03 signal line (signal line name: SUBHYON) is "Hi"
The individual power control transistor 110
4 (hereinafter, TR2) is turned on, and a voltage of about VM volt is applied to SUBHY. Similarly, the control of the sub heaters (SUBHM, SUBHC, SUBHK) for the remaining three colors is performed by the interface transistors 1105 and 110.
7, 1109 and individual power control transistor 1106
(Hereinafter, TR3), 1108 (hereinafter, TR4), 111
0 (hereinafter referred to as TR5). SUBHM is a magenta (M) sub-heater, SUBHC is a cyan (C) sub-heater, and SUBHK is a black (K) sub-heater.

At this time, for example, when the SUBHK element itself has a short circuit failure or when the control terminal is adjacent to the GND.
When it is in contact with the (ground: ground) terminal, TR1 of the power supply transistor and TR5 of the individual power control transistor are turned on with almost 0 ohm resistance, causing thermal breakdown from TR5 having a small maximum allowable power to cause short circuit breakdown. Becomes

Therefore, in this embodiment, the abnormality detection circuit is used as a collector terminal of TR1 and TR2, TR3, TR.
Resistor 1 is connected to the emitter terminal of TR4 and TR5.
111 and a capacitor 1112 are connected in series with respect to GND (ground potential). Then, the voltage dividing resistors 1113 and 1114 are connected to both ends of the capacitor 1112, and the divided voltage (signal name: Error) is connected to the analog voltage input port of the microcomputer (not shown) described above. Monitor (observe).

FIG. 8 shows the O of the power supply transistor TR1, the individual power control transistors TR2, TR3, TR4 and TR5 in the test mode of the sub-heater control circuit of FIG.
The N / OFF sequence and the voltage waveform generated at the Error terminal (divided voltage terminal) at that time are shown. When all the transistors TR1 to TR5 are turned off (T1 period), the voltage at the Error terminal is around 0V.

Next, when only the transistor of TR1 is turned on, the voltage at the Error terminal rises due to the series time constant of the resistor 1111 and the capacitor 1112 (T2 period).
Here, in this example, the resistance value of the resistor 1111 is set to be substantially the same as the resistance value of the sub-heater, and is set to −110 ohm (Ω). The capacitance of the capacitor 1112 was set to 220 μF by setting the charging time of the capacitor 1112 to be easily measured by the microcomputer (for example, the time for counting the timer interrupt time by several tens of times) as about 20 ms.

Next, all the transistors TR1 to TR5
Is turned off again and waits for a certain time (T3 period). At this time, the electric charge of the capacitor 1112 is the voltage dividing resistor 1113.
And 1114 are consumed. This voltage dividing resistor 1113
The resistance values of 1114 and 1114 are configured to have a resistance ratio that does not exceed the ratio of the VCC voltage (5V in this example) to the VM voltage (28V in this example), and are 100 times or more that of the resistor 1111.
Resistor 1113 is -12 kOhm, resistor 1114 is-
It was 2.5 kilohms.

Next, only the transistor of TR2 is turned on, and the charge stored in the capacitor 1112 is transferred to the resistor 111.
1 and the sub-heater (SUBHY) series resistance consumes about 220 ohms and 220 μF as described above.
The voltage decays with the time constant of the capacitor (T4Y
Period) (solid line: curve of A).

This sub-heater (SUBHY) and resistor 11
If the time constants of 11 and the capacitor 1112 are as described above, the voltage will be 0 V in about 40 ms, but if the sub heater (SUBHY) is short-circuited, it will be attenuated with a time constant of about 110 ohm and 220 μF. Therefore, the voltage becomes 0 V in about 20 ms (broken line: curve B).

If the above sequence is sequentially performed for the remaining three color sub-heaters SUBHM, SUBHC and SUBHK, it becomes possible to detect the short-circuit failure of all the sub-heaters.

Further, as shown in FIG. 9, when a voltage is detected at the Error terminal even though all the transistors TR1 to TR5 are in the OFF state (T1 period), the power supply transistor TR1 has a short circuit failure. Is the case
Since it is a good idea not to control the sub-heater thereafter, the microcomputer displays a message to that effect on the display means (not shown) to stop the function of the device itself.

Further, as shown in FIG.
112 is completely charged, and all the transistors TR1 to TR1
When TR2 is in the OFF state (T3 period), the voltage drops while watching (broken line: C curve)
Because at least one of the transistors TR2, TR3, TR4, TR5 is in a short circuit fault condition,
Because the current is flowing through the sub heater,
In this case as well, since it is a good idea not to control the sub-heater thereafter, the microcomputer displays a message to that effect and stops the function of the device itself.

FIG. 11 shows an instruction flowchart of the microcomputer for executing the sequence described above, and the detailed description thereof will be added below.

First, when the power is turned on (S1), all the transistors TR1, TR2, TR3, TR4 and TR5 are turned off.
Then (S2), wait for 10 msec (S3). At that time, if the Error terminal of FIG. 7 is at the “Hi” level (S4), it means that the transistor TR1 has a short-circuit failure (see FIG. 9), that fact is displayed (S5), and the main body operation (specifically, Stops all operations other than the microcomputer displaying an error) (S6).

Next, when it is determined that the transistor TR1 does not have a short-circuit fault, the transistor TR1 is turned on (S7), waits for 20 msec (S8), and charges are stored in the capacitor 1112. And the transistor TR1
Is turned off (S9), the state of the Error terminal is checked (S10), and if the state is "Low" (low level),
This is because the transistor TR1 could not pass the current, and therefore, the open failure of the transistor TR1 is displayed (S1
1) The operation of the main body is stopped (S12).

Erro if the transistor TR1 is normal
Since the r terminal becomes "Hi" level in S10, wait 10 msec (S13) and watch the Error terminal again (S1).
4). At this time, if the Error terminal is at the “Low” level, the charge of the capacitor 1112 is the T
Since it is consumed by the sub-heater through any one of R2, TR3, TR4, and TR5, at least any one or more of these four transistors has a short circuit failure (see FIG. 10). Then (S1
5) The operation of the main body is stopped (S16).

Next, since the electric charge stored in the capacitor 1112 is consumed by the yellow (SUBHY) resistance of the sub-heater through the transistor TR2, the transistor T2 is consumed.
Turn on R2 (S17) and wait 20 ms (S1
8) If the voltage of the Error terminal at that time is "Low" (S19), the discharge time constant is only the resistor 1111, that is, the sub-heater yellow (SUBHY) is in a short circuit state (see the curve B in the T4Y period in FIG. 8). (See), display that effect (S20), and stop the main body operation (S21).

At S19, the voltage at the Error terminal is reversed to "H".
If i ", the transistor TR2 is kept in the ON state for another 20 ms (S22), and if the voltage at the Error terminal thereafter is still" Hi "(S23), the transistor T2 is turned on.
Since it is possible to determine that the transistor TR2 or SUBHY has an open failure because R2 or the yellow SUBHY of the sub-heater could not pass the current, it is displayed (S24) and the main body operation is stopped (S25).

In S23, the voltage at the Error terminal is "Lo".
If it is w ", the transistor TR2 is turned off (S26). When reaching this sequence, it can be determined that the sub-heater yellow (SUBHY) power supply system, the resistor, and the connection line are normal (S2).
7).

The sub-heater magenta (SUBH
M), cyan (SUBHC), black (SUBHK)
Regarding, regarding the sub-heater, the abnormality can be detected by sequentially performing the same sequence as S7 to S27.

(Second Embodiment) In the above-described first embodiment of the present invention, a heater (electrothermal conversion element) was described as an example of a load that receives power supply, but the present invention is not limited to this. , For example, a lamp, an LED (light emitting diode), a semiconductor laser, an electro-optical conversion element such as electroluminescence, a solenoid, an electrodynamic conversion element such as an electrostrictive vibrator, or an electro-magnetic conversion element such as a magnetic head or a charger is used as a load. The present invention can be similarly applied to the abnormality detection circuit of the power supply circuit.

(Third Embodiment) FIG. 12 shows a configuration example in which the abnormality detection circuit of the present invention is applied to a DC motor control circuit capable of controlling forward and reverse rotations. 4 transistors TR
The DC motor M is connected to the middle point of the bridge circuit consisting of 1, TR2, TR3 and TR4, the resistor 1401 and the capacitor 1402 are connected in series between one side of this motor winding and GND, and both ends of the capacitor 1402 are connected. In order to monitor the voltage, the voltage of the voltage dividing resistors 1403 and 1404 is connected to an analog input port of a microcomputer (not shown), and the voltage is monitored by the microcomputer.

Normally, the transistors of the bridge circuit are controlled so that the transistors arranged in the cross are simultaneously turned on, and the transistors connected in series are not turned on at the same time. However, in this example, all the transistors TR1 to TR4 are
Has an ON / OFF controllable structure independently.

The microcomputer first turns off all the transistors TR1, TR2, TR3 and TR4 and measures the voltage at the Error terminal to determine the transistor TR.
1, Check whether or not there is a short circuit fault in TR3.

Next, by turning the terminal A to "Hi", only the transistor TR1 is turned on, and the capacitor 1402 is turned on.
Stores a charge of about VM volt. This makes the error
If the voltage at the terminal rises, it can be determined that the transistor TR1 can be controlled and that the transistor TR2 is not short-circuited. Therefore, set terminal A to "Lo
The transistor TR1 is turned off by setting "w".

Next, after confirming that the voltage at the Error terminal does not drop (if the voltage at the Error terminal does not drop, it can be determined that the transistor TR4 is not a short-circuit fault), the terminal B is set to "Hi". Then, the transistor TR2 is turned on. At this time, if the voltage drops due to the time constant of the resistor 1401 and the capacitor 1402, the transistor TR2 is normal.

After that, it waits until the voltage at the Error terminal has dropped to 0V, turns on the transistor TR1 again, and then turns the terminal D to "Hi" to turn on the transistor TR4. If the voltage changes from the decay waveform when the transistor TR2 is turned on and is attenuated, it can be determined that the transistor TR4 is discharged through the winding of the motor M. That is, the change in the attenuation waveform of the voltage at the Error terminal is because the transient change in the current is obstructed by the inductance of the winding of the motor M.

Finally, the transistor TR3 is turned on by setting the terminal to "Hi", which causes the error.
If the voltage at the terminal rises, it can be determined that the transistor TR3 is also normal.

(Other Embodiments) The present invention may be applied to a system including a plurality of devices or an apparatus including a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. Becomes

[0067]

As described above, according to the present invention,
Only one set of charging / discharging circuit is provided in the power supply means for individually and independently controlling the load by using the power control element, and the time variation of the voltage across the charging element constituting the charging / discharging circuit is
Since the measurement is performed in synchronization with the ON / OFF control of the power control element, it is possible to detect the abnormality of the power control element and the abnormality of the load, respectively.

That is, the failure of the power control element that supplies power to a large number of loads, the failure of the loads and the abnormality of the connection state of the loads, the charging / discharging circuit including only one set of the resistor and the capacitor, and the capacitor It is possible to detect the voltage only by providing a monitor circuit (microcomputer) for monitoring the voltage.

Further, when the abnormality of the power control element or the load is detected, the operation of the device is stopped, so that the secondary damage of the replacement unit can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an inkjet recording apparatus to which the present invention can be applied.

FIG. 2 is an enlarged perspective view showing the carriage of the inkjet recording apparatus shown in FIG. 1 in detail.

3 is a block diagram showing an electrical configuration of the inkjet recording apparatus shown in FIG.

FIG. 4 is a block diagram showing a circuit configuration of the recording head of FIG.

5 is an exploded perspective view showing the structure of the recording head of FIG. 1. FIG.

FIG. 6 is an exploded perspective view showing the structure of the recording head unit of FIG.

FIG. 7 is a circuit diagram showing a configuration of a power supply control circuit including a power supply circuit and its abnormality detection circuit that best represent the characteristics of the first exemplary embodiment of the present invention.

8 is a waveform diagram showing changes in the output waveform of the abnormality detection circuit of FIG.

9 is another one of changes in the output waveform of the abnormality detection circuit of FIG.
FIG. 6 is a waveform diagram showing one of the above.

10 is a waveform chart showing still another change in the output waveform of the abnormality detection circuit of FIG.

11 is a flowchart showing a sequence of control operations of the abnormality detection circuit of FIG.

FIG. 12 is a circuit diagram showing a configuration of an abnormality detection circuit of a power supply circuit to a motor as a load in the second embodiment of the present invention.

FIG. 13 is a circuit diagram showing a configuration of a conventional abnormality detection circuit.

FIG. 14 is a circuit diagram showing another configuration of a conventional abnormality detection circuit.

[Explanation of symbols]

1 Recording Head Unit 1Y, 1M, 1C, 1K Recording Head 11 Image Signal Processing Device 101 Discharge Heater 104 Decoder 107 Temperature Adjustment Sub-heater 108 Dummy Resistors 109a, 109b Diode (Temperature Sensor) 100 Board (Heater Board) 200 Wiring Board 1101, 1103, 1105, 1107, 1109
Interface transistor 1102 Power supply transistor 1104, 1106, 1108, 1110 Power control transistor 1111 Abnormality detection circuit resistance (resistor) 1112 Abnormality detection circuit capacitor 1113, 1114 Abnormality detection circuit voltage dividing resistor (resistor) 1401 Abnormality detection circuit Resistance (resistor) 1402 capacitor of abnormality detection circuit 1403, 1404 voltage dividing resistance (resistor) of abnormality detection circuit SUBHY, SUBHM, SUBHC, SUBHK temperature adjustment sub-heater error output terminal of abnormality detection circuit M motor

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Noriyuki Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Uemura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Nobuyuki Tsukada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. A plurality of loads, a plurality of power control elements for controlling the power of the loads, at least one power supply element connected to the load and a common connection terminal other than the GND terminal, and the power control element. And a control element capable of independently controlling the power supply element, a resistor and a capacitor connected in series between the common connection terminal and the GND potential, and by observing a change in voltage across the capacitor, An abnormality detection device for an electric power supply circuit, comprising: an abnormality detection means for detecting an abnormality in the electric power supply circuit. 2. The abnormality detecting means according to claim 1, wherein the voltage dividing resistors connected to both ends of the capacitor and the power control element and the power supply element are sequentially and independently provided via the control element. By performing ON / OFF control and observing a temporal change in voltage across the capacitor obtained from the voltage dividing resistor in synchronization with ON / OFF control of the power control element, the power control element, the power An abnormality detection device for a power supply circuit, comprising: a supply element; and a control unit that detects an abnormality in each of the loads. 3. The control device according to claim 2, wherein when the control means detects an abnormality in at least one of the power control element, the power supply element, and the load, the main body device including the load is stopped. An abnormality detection device for a power supply circuit, comprising: 4. The control device according to claim 2 or 3, wherein when the control means detects an abnormality in at least one of the power control element, the power supply element and the load, the control means indicates that the abnormality is detected. An abnormality detection device for a power supply circuit, characterized by displaying on a display means. 5. The abnormality detection device for a power supply circuit according to claim 1, wherein the load is an electrothermal conversion element. 6. The abnormality detection device for a power supply circuit according to claim 1, wherein the load is an electro-optical conversion element. 7. The abnormality detection device for a power supply circuit according to claim 1, wherein the load is an electrodynamic conversion element. 8. The abnormality detection device for a power supply circuit according to claim 1, wherein the load is an electro-magnetic conversion element. 9. A load, a bridge circuit including a plurality of power control elements for controlling the electric power of the load, a control element capable of independently controlling the power control element, and the load connected to a middle point of the bridge circuit. A resistor and a capacitor connected in series between one side of the capacitor and the GND potential, and an abnormality detecting means for detecting an abnormality of the power supply circuit by observing a change in voltage across the capacitor. Characteristic power supply circuit abnormality detection device. 10. The abnormality detecting device according to claim 9, wherein the abnormality detecting unit sequentially turns on the voltage dividing resistors connected to both ends of the capacitor and the power control element via the control element.
By performing N / OFF control and observing a temporal change of the voltage across the capacitor obtained from the voltage dividing resistor in synchronization with ON / OFF control of the power control element, an abnormality of the power control element is detected. An abnormality detection device for a power supply circuit, comprising: a control unit that detects the abnormality. 11. The control device according to claim 10, when the control unit detects an abnormality of the power control element, displays the fact that the abnormality is detected on the display unit and stops the main body device including the load. An abnormality detection device for a power supply circuit, comprising: 12. The abnormality detection device for a power supply circuit according to claim 9, wherein the load is a DC motor.