KR100449104B1 - Power supply controlling device of inkjet printer - Google Patents

Abstract

Disclosed is a power supply control apparatus of an inkjet printer. A power control apparatus of an inkjet printer having a head driver, a power supply for supplying power to the head driver, and a control part for outputting a control signal for driving the head driver, the on / off switching operation according to the control signal of the controller is performed. A driving switching unit, a power switching unit for intermitting the power supply by the on / off switching operation of the driving switching unit, an overcurrent sensing unit sensing an overcurrent supplied to the head driving unit when the power switching unit is turned on, and an overcurrent sensing unit Compared to the over-current reference voltage and the over-current output voltage corresponding to the over-current detected by the, and the over-current output voltage exceeds the over-current reference voltage has a power control unit for controlling the power switching unit to cut off the power supply to the head drive unit . Thus, by detecting the current applied to the printing element and the peripheral circuit, such as the printhead, and cut off the power supply to the printing element and the peripheral circuit when the overcurrent is detected, by simultaneously discharging the remaining charge remaining in the printing element and the printing element and Peripheral components can be protected.

Description

Power supply controlling device of inkjet printer

The present invention relates to a power supply control apparatus of an inkjet printer, and more particularly, to a power supply control apparatus of an inkjet printer capable of controlling power supply or interruption to a printing element such as a printhead driven when performing a printing operation. It is about.

Printers are the most common means for outputting computer-processed information in a form that can be seen by a human, and there are inkjet printers and laser printers according to printing methods.

An inkjet printer is formed of an ink cartridge having a plurality of nozzles for ejecting ink for forming an image on a recording sheet according to a printing command, and an ink cartridge driving circuit for driving an ink cartridge.

According to the print command, the head driving part that is operated when performing a print job may be overloaded during printing, or an abnormal operation may occur in the ink cartridge or the driving circuit for driving the print cartridge due to some physical action, which may damage the print head and other peripheral circuits. .

Therefore, the conventional inkjet printer includes an overcurrent protection element on a power supply line that is supplied with power to the printing element to supply power to the printhead and other peripheral circuits within the range allowed by the overcurrent protection element. In this case, the overcurrent may be supplied to a printing element such as a print head due to a defective part or a malfunction of the overcurrent protection element.

In addition, voltage stabilizing capacitors are provided for voltage stabilization of the printhead and peripheral circuits. However, since the power is arbitrarily cut off during the printing operation, even if the power supply to the printing element is cut off, the printhead and the peripheral parts may be damaged due to the remaining charge remaining in the voltage stabilizing capacitor.

The technical problem to be achieved by the present invention, it is possible to cut off the power supply to the printing element when the over current occurs by determining whether the over current is applied to the printing element required to perform the printing operation, the power control device of the inkjet printer that can inform the user whether the over current occurs To provide.

1 is a block diagram of an inkjet printer system having a power supply control apparatus according to a preferred embodiment of the present invention;

FIG. 2 is a block diagram of the power control apparatus shown in FIG. 1, and

3 is a detailed circuit diagram of the power control device shown in FIG. 2.

Explanation of symbols on the main parts of the drawings

100: host computer 200: printer

210: input unit 220: DC / DC converter

230: signal processing unit 240: printing unit

250: display unit 260: power control device

In order to solve the above technical problem, the power control device of the ink-jet printer having a head drive unit, a power supply for supplying power to the head drive unit and a control unit for outputting a control signal for driving the head drive unit is the control unit A driving switching unit for performing an on / off switching operation according to a control signal of the power supply unit, a power switching unit for controlling the power supply of the power supply unit by an on / off switching operation of the driving switching unit, and the head driving unit when the power switching unit is turned on Comparing the overcurrent output voltage corresponding to the overcurrent sensed by the overcurrent sensor with the overcurrent reference voltage to the preset overcurrent reference voltage, when the overcurrent output voltage exceeds the overcurrent reference voltage; The power switching unit to cut off the power supply to the head drive unit It has a power supply control part for controlling.

Preferably, the apparatus further includes a voltage sensing unit configured to sense an input voltage applied from the power supply unit, wherein the power control unit compares the input voltage sensed by the voltage sensing unit with a preset discharge reference voltage. When the voltage is less than or equal to the discharge reference voltage, the power switching unit is controlled to cut off the power supply to the head driving unit.

The power control unit compares the overcurrent reference voltage and the overcurrent reference voltage according to an output of the voltage preprocessor and a voltage preprocessor for generating any one of the overcurrent reference voltage and the discharge reference voltage. A second comparison result of comparing a voltage comparison unit performing any one of voltage comparison with a comparison result signal of the voltage comparison unit and a signal delayed by a predetermined time with respect to an on / off signal of the driving switching unit, and outputting a logic signal corresponding to the comparison result; A signal generator for outputting an inverted signal with respect to the logic signal output from the logic element and the second logic element, a signal input corresponding to on / off from the driving switching unit, and a signal input from the signal generator Compare the control signal with the power supply unit according to the comparison result. And a first logic element output to the power supply switching unit.

And a discharge circuit unit configured to discharge residual charge remaining in the capacitor for stabilizing the voltage supplied to the head driving unit by the output signal of the first logical element.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of an inkjet printer system having a power supply control apparatus according to a preferred embodiment of the present invention.

Referring to the drawings, the inkjet printer system includes a host computer 100 and an inkjet printer 200.

The host computer 100 transmits a control signal for controlling the inkjet printer 200 such as print data and a print command to the inkjet printer 200 and a predetermined power for driving the signal processor 230 of the inkjet printer 200. do.

The inkjet printer 200 performs a print job on print data in response to a print command input from the host computer 100.

The inkjet printer 200 includes an input unit 210, a DC / DC converter 220, a signal processor 230, a print unit 240, a display unit 250, and a power control device 260.

The input unit 210 includes a plurality of function keys (not shown) for receiving a user's selection command for the inkjet printer 200 such as a print command. The input unit 210 is installed on the main body of the inkjet printer 200 to directly receive a selection command from the user.

The DC / DC converter 220 supplies a predetermined voltage (+ 5V) supplied from the host computer 100 or the power controller 260, which will be described later, to the signal processor 230 (+ 2.5V or + 3.3V). The conversion is performed to supply the voltage necessary for driving the signal processor 230.

The signal processor 230 includes a USB interface unit 232, a storage unit 234, and a controller 236, and controls the operation of the inkjet printer 200. The driving voltage for operating the signal processor 230 is approximately + 2.5V to + 3.3V.

The USB interface unit 232 is a connection portion between the inkjet printer 200 and the host computer 100 and is generally connected to the parallel port of the host computer 100.

The storage unit 234 stores various programs and print data necessary to perform an operation of the printer. The storage unit 234 may include an inactive memory device such as a ROM in which various control programs necessary for implementing the functions of the inkjet printer 200 are stored, and a RAM for temporarily storing various data generated during the operation of the inkjet printer 200. It has a volatile memory device such as.

The controller 236 controls the overall operation of the inkjet printer 200 according to a program stored in the storage unit 234 when the printer is powered on.

The controller 236 outputs a control signal for driving the printer 240 to the power controller 260 according to whether print data is received from an external device or a signal corresponding to a print command. That is, the controller 236 outputs a power on / off control signal for controlling the power supply to the printing unit 240 and the cutoff to the power controller 260.

The controller 236 may receive a signal output from the power control device 260 to know whether or not an error occurs in the printing unit 240. The controller 236 may transmit the occurrence of an abnormality of the print unit 240 received from the power control device 260 to the user through the display unit 250 and a speaker (not shown).

The printing unit 240 is operated by the power supplied from the power control unit 260, and performs printing on the print data received through the USB interface unit 232 under the control of the control unit 236, which will be described later. . The print unit 240 includes a print head for performing a printing operation, a head transfer motor for transferring the print head, a print head driver, and the like. The printing unit 240 is supplied with a driving voltage (approximately + 30V) required to drive each element from the power supply unit 261.

The display unit 250 displays an operation state of the entire printer under the control of the controller 236.

The power controller 260 determines whether power is supplied to the printing unit 240 in response to a power on / off control signal input through the controller 236. In addition, the power control device 260 checks the malfunction caused by the change of the input current and the overcurrent that may be generated when the power supply to the print unit 240 or the power cut off to cut off the power supply to the print unit 240. Can be.

FIG. 2 is a block diagram of the power control device shown in FIG. 1, and FIG. 3 is a detailed circuit diagram of the power control device shown in FIG.

Referring to the drawings, the power controller 260 includes a power supply unit 261, a driving switch unit 263, a power switch unit 265, an overcurrent detector 267, a discharge circuit unit 269, and a power controller 270. Has

The power supply unit 261 supplies power to the entire system of the inkjet printer 200. The power supplied by the power supply 261 is approximately + 30V. In order to avoid the complexity of the drawing, only the power supply path from the power supply unit 261 to the printing unit 240 is shown.

The driving switching unit 263 performs an on / off switching operation according to the power on / off signal of the controller 236. The driving switching unit 263 is turned on in response to the power on signal from the controller 236, and is turned off in response to the power off signal.

The power switching unit 265 is installed between the power supply unit 261 and the printing unit 240 to intercept the power to the printing unit 240 by the on / off switching operation of the driving switching unit 263.

The power switching unit 265 is disposed to be turned on or off according to a switching operation of the first switching unit 265a and the first switching unit 265a connected to the output terminal of the first and gate 271 to be described later. And second switching portions 265b and 265c.

The power switching unit 265 performs an on / off switching operation according to the output signal of the first and gate 271. For example, when the output signal of the first and gate 271 is high, it is turned on, and when the output signal of the first and gate 271 is low, it is turned off. Therefore, the power supply to the printing unit 240 is interrupted according to the output signal of the first and gate 271.

The overcurrent detecting unit 267 is installed between the power supply unit 261 and the printing unit 240 to detect an overcurrent supplied to the printing unit 240 when the power switching unit 265 is turned on.

The overcurrent detector 267 includes bias resistors 267a and 267b and a third switching unit 267c. When the power switching unit 265 is turned on, driving power (+ 30V) supplied from the power supply unit 261 is supplied to the printing unit 240, where the emitter terminal of the third switching unit 267c When the voltage is approximately 0.7 V higher than the voltage of the base terminal, the third switching unit 267c is turned on.

That is, the overcurrent detector 267 detects whether the current induced by the bias resistors 267a and 267b exceeds the threshold current (for example, 14A).

The power controller 270 compares the overcurrent output voltage detected by the overcurrent detector 267 with the overcurrent reference voltage, and when the overcurrent output voltage is greater than the overcurrent reference voltage, cuts off the power supply to the printing unit 240. The power switching unit 265 is controlled.

The power controller 270 includes a first and gate 271, a voltage preprocessor 273, a voltage comparator 275, a second and gate 279, a delay unit 276, and a signal generator 280.

In the first and gate 271, two input terminals are respectively connected to an output terminal of the driving switching unit 263 and an output terminal of the signal generator 280 to be described later. The first and gate 271 receives an output signal of the driving switch unit 263 and an output signal of the signal generator 280 and compares the two signals. The output of the first and gate 271 outputs a high or low signal according to a result of comparing the two signals. The output of the first gate 271 outputs a high signal only when both signals are high signals according to the characteristics of the AND circuit.

The voltage preprocessor 273 serves to provide two inputs of the voltage comparator 275 to be described later. The voltage preprocessor 273 provides the current output to the overcurrent detector 267 as the positive terminal of the voltage comparator 275 to supply the overcurrent output voltage which is voltage-dropped through the plurality of resistors R1 and R2. The negative terminal provides an overcurrent reference voltage.

The voltage preprocessor 273 includes a test power supply (+ 5V) for forming an overcurrent reference voltage at an input terminal of the voltage comparator 275, and a voltage distribution resistor R3 for distributing a voltage between the test power supply (+ 5V) and ground. R4) is used to generate an overcurrent reference voltage.

The voltage comparison unit 275 compares the overcurrent reference voltage input from the voltage preprocessor 273 to the negative terminal and the overcurrent output voltage input from the overcurrent detection unit 267 to the positive terminal. Therefore, a high or low signal is output. As a voltage comparator 275, a comparator is applied to receive two input signals and compare the magnitudes of the two input signals and output the result.

The voltage comparator 275 outputs a high signal when the overcurrent output voltage exceeds the overcurrent reference voltage as a result of the comparison of the two voltages.

In the second AND gate 279, two input terminals are respectively connected to an output terminal of the voltage comparator 275 and an output terminal of the delay unit 276 which will be described later. The first and gate 271 receives an output signal of the voltage comparator 275 and an output signal of the delay unit 276 and compares the two signals.

The output of the second and gate 279 outputs a high or low signal according to the comparison result of the two signals. Similar to the first and gate 271, the output of the second and gate 279 outputs a high signal only when both signals are high signals. Accordingly, the output of the second and gate 279 outputs a low signal even when any one of the two signals is low.

The delay unit 276 delays the output signal of the driving switching unit 263 for a predetermined time by the power-on signal from the controller 236. As the delayer 276, an integrating circuit formed by connecting the output signal of the driving switching unit 263 to the capacitor 276b and the resistance element 276a in parallel is used.

The signal generator 280 inverts and outputs the state of the signal output from the second and gate 279.

As the signal generator 280, a D-flip flop 280a is applied. The output of the D-flip flop 280a is output from an output terminal for outputting a signal inverted with respect to the input signal. Therefore, when the output signal of the second and gate 279 is shifted from low to high, the output signal of the D-flip flop 280a becomes a low signal. Description of the D-flip-flop 280a will be easily understood by those skilled in the art, and a detailed description thereof will be omitted. The output signal of the D-flip flop 280a is fed back to the output terminal 290 denoted as output A and the input terminal of the first and gate 263. The signal input to the output terminal 290 is provided to the controller 236.

The discharge circuit unit 269 includes a first resistor 269a having one side connected to an output terminal of the first and second gates 271, a first transistor 269b having a base end connected to the other side of the first resistor 269a, and a first resistor 269b. The second transistor 269c having the base connected to the collector terminal of the transistor 269a, the second resistor 269d and the collector of the second transistor 269c connected between the collector terminal of the first transistor and the test power supply 5V. A third resistor 269e connected to the stage is formed. One end of the third resistor 269e is branched on a connection line connected to the printing unit 240 from the output terminal of the power switching unit 265.

When the output of the first and gate 271 is a high signal, the discharge circuit unit 269 turns on the first transistor 269b so that a voltage close to 0V is induced at the collector terminal of the first transistor 269b. Accordingly, the second transistor 269c is turned off. Therefore, when the output of the first and gate 271 is a high signal, the discharge circuit unit 269 does not operate.

On the other hand, when the output of the first and gate 271 is a low signal, the first transistor 269b is turned off and a voltage of about 5V is applied to the collector terminal of the first transistor 269b. Accordingly, the second transistor 269d is turned on so that the ground voltage is applied to the collector terminal of the second transistor 269d. Therefore, when the output of the first and second gates 271 is a low signal, the residual charge remaining in the voltage stabilizing capacitor (not shown) for stabilizing the printing element of the printing unit 240 is applied to the emitter terminal of the second transistor 269d. Passed and discharged.

Hereinafter, the operation of the power supply control device when receiving the power-on control signal from the control unit 236 will be described.

When the driving switching unit 263 is turned on by the power-on control signal from the control unit 236 at the input terminal of the driving switching unit 263, the power switching unit 265 is turned on accordingly. When the power switching unit 265 is turned on, the driving voltage (+ 30V) of the printing unit 240 is induced to the printing unit 240 through the overcurrent detecting unit 267. At this time, the overcurrent detecting unit 267 detects a current induced by the printing unit 240 and detects whether the current supplied to the printing unit 240 exceeds a threshold current.

The voltage comparator 275 compares the overcurrent output voltage input from the voltage preposition unit 273 to the positive terminal and the overcurrent reference voltage input to the negative terminal, and as a result of comparison, the overcurrent output voltage is the overcurrent reference voltage. If it is larger, a high signal is output.

The second and gate 279 receives and compares the high signal applied from the voltage comparator 275 with the output signal of the driving switch 263 turned on by the power on control signal from the controller 236. In this case, since both input signals are high signals, the output signal of the second and gate 279 becomes a high signal.

The D-flip-flop 280a receiving the high signal from the second and gate 279 feeds back the low signal inverted with respect to the high signal to the output terminal 290 and the first end gate 271 denoted as output A.

In this case, since the signal fed back to the first and gate 271 is a low signal, the output of the first and gate 271 becomes a low signal. Therefore, the power switching unit 265 is turned off by the output signal of the first and gate 271, so that the power supply to the printing unit 240 is cut off.

On the other hand, even when the power supply to the printing unit 240 is cut off, residual charge exists in the voltage stabilizing capacitor (not shown) for stabilizing the printing element required to perform the printing operation. Therefore, even if the power supply is cut off from the power supply 261, the printhead and the peripheral parts may be damaged due to the remaining charge remaining in the printing element.

In this case, when a low signal is input from the output terminal of the first and gate 271, the discharge circuit unit 269 is driven so that the residual voltage remaining in the voltage stabilizing capacitor (not shown) for stabilizing the printing element such as the print head is reduced. It is discharged through the emitter stage of the two transistors 269c.

Meanwhile, the output signal of the voltage comparing unit 275 when the overcurrent is generated on the power supply path to the printing unit 240 has been described. However, even when the input voltage of the voltage supply unit 261 falls, that is, when the power is cut off due to a power failure or an unplugged power cord, the voltage comparison unit 275 may be driven by the discharge reference voltage formed by the voltage preprocessor 273. have.

The zener diode 300a and the plurality of resistance elements 300b, 300c, and 300d are connected between the power supply 261 and the ground terminal to form a current path in series. The zener diodes 300a and the resistors 300b and 300c are applied as the voltage sensing unit 300 for detecting the change of the driving voltage (+ 30V) supplied from the power supply unit 261.

Therefore, when the driving voltage (+ 30V) supplied from the power supply unit 261 is lowered due to the above reason, the voltage induced in the cathode terminal of the zener diode 300a is dropped, and the dropped voltage is negative of the voltage comparator 275. Since the voltage is lower than the voltage applied to the negative terminal, the diode D1 conducts to lower the voltage applied to the negative terminal of the voltage comparator 275.

The voltage comparator 275 receives the discharge reference voltage formed by the voltage divider resistors R5 and R6 of the voltage preprocessor 273 as a positive terminal and receives a voltage drop in the negative terminal. Take the input and compare the two signals. As a result of the comparison, a high signal is output when the input voltage applied to the negative terminal is less than the discharge reference voltage applied to the positive terminal.

The high signal output through the output terminal of the voltage comparator 275 is input to any one of two input terminals of the second and gate 279. Since the operation is the same as the case where the overcurrent signal is detected above, it will be omitted. That is, even when the input voltage of the power supply unit 261 is lowered, the power supply switching unit 265 may be turned off to cut off the power supply to the printing unit 240, and the remaining charge remaining in the voltage stabilizing capacitor may also be discharged. You can.

The operation of the power control device 260 when the power-on control signal is received from the control unit 236 has been described above, and the case where the power-off control signal is received from the control unit 236 will be described.

When power is being supplied to the printing unit 240 and a signal corresponding to the power-off is received from the control unit 236 at the first and second gates 271, the output of the first and second gates 271 becomes a low signal. The unit 265 is turned off to cut off the power supply to the printing unit 240. At the same time, when the low signal is input to the discharge circuit unit 269 and the first transistor 269b is turned off, the second transistor 269c is turned on. Therefore, the remaining charge remaining in the voltage stabilizing capacitor is current-passed to the emitter terminal of the second transistor 269c to be discharged.

As described above, when an overcurrent is sensed on the power supply line supplied to the printhead and the printhead driver, or when the power-off signal is received from the controller 236, the power supply to the printer 240 may be cut off.

As described above, according to the power control apparatus of the inkjet printer according to the present invention, when an overcurrent is detected by detecting a current applied to the printing element and the peripheral circuit, the power supply to the printing element and the peripheral circuit is cut off, and By discharging the residual charge remaining in the printing element, the printing element and the peripheral parts can be protected.

Although the present invention has been described in detail with reference to exemplary embodiments above, those skilled in the art to which the present invention pertains can make various modifications to the above-described embodiments without departing from the scope of the present invention. I will understand. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

Claims (4)

A power control apparatus of an inkjet printer, comprising: a head driver, a power supply for supplying power to the head driver, and a controller for outputting a control signal for driving the head driver. A voltage sensing unit sensing an input voltage applied from the power supply unit; A driving switching unit configured to perform an on / off switching operation according to a control signal of the controller; A power switching unit for controlling the power supply of the power supply unit by an on / off switching operation of the driving switching unit; An overcurrent detector configured to sense an overcurrent supplied to the head driver when the power switching unit is turned on; And Compare the overcurrent output voltage with a preset overcurrent reference voltage in response to the overcurrent detected by the overcurrent sensing unit, and cut off the power supply to the head driving unit when the overcurrent output voltage exceeds the overcurrent reference voltage. To control the switching unit, A power control unit comparing the input voltage sensed by the voltage sensing unit with a preset discharge reference voltage and controlling the power switching unit to cut off power supply to the head driving unit when the input voltage is less than or equal to the discharge reference voltage; Power control device for an inkjet printer, characterized in that it comprises a. delete The method of claim 1, The power control unit, A voltage preprocessor configured to generate one of the overcurrent reference voltage and the discharge reference voltage; A voltage comparing unit configured to compare the overcurrent reference voltage with the overcurrent reference voltage and compare the discharge reference voltage with the input voltage according to an output of the voltage preprocessor; A second logic element configured to compare a comparison result signal of the voltage comparing unit and a signal delayed by a predetermined time with respect to the on / off signal of the driving switching unit, and output a logic signal corresponding to the comparison result; A signal generator for outputting a signal inverted with respect to the logic signal output from the second logic element; And Comparing a signal input corresponding to on / off from the driving switching unit with a signal input from the signal generating unit, and outputting a control signal to the power switching unit to control the power supply of the power supply unit according to a comparison result; 1 logic element; power supply control apparatus for an inkjet printer comprising a. The method of claim 3, wherein And a discharge circuit unit configured to discharge residual charge remaining in the capacitor for stabilizing the voltage supplied to the head driving unit by the output signal of the first logical element.