KR100193853B1 - Head drive steady state detection and head protection - Google Patents

Abstract

end. TECHNICAL FIELD OF THE INVENTION

Head driving state steady state detecting device and head protecting device.

I. Technical Problems to be Solved by the Invention

Detects a normal state of the head driving device, and protects the head from an abnormality of the head driving device when an abnormality of the head driving device occurs.

All. The point of the solution of the invention

A plurality of heating elements are provided to heat the nozzles to spray ink in the nozzles and to have a plurality of driving transistors to cut off or connect the power supply path of the heating elements and to supply a plurality of head driving signals A head driving device for controlling a power supply path by conducting or not conducting the driving transistor in accordance with a received head driving signal; a power supply for applying power to the head driving device; A reference voltage set to a magnitude obtained by converting a magnitude of a current into a voltage, a voltage across the resistor, and an emitter current when one nozzle is driven, A comparator for generating an interrupt signal indicative of an abnormal state of the head driving device, And a power supply unit for supplying power to the head driving unit. The power supply unit supplies power to the head driving unit. The power supply unit supplies power to the head driving unit. And a control unit for shutting down the battery.

la. Important Uses of the Invention

It can be usefully used for a head protecting device of an ink jet printer.

Description

Head drive steady state detection and head protection

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly, to a head driving apparatus steady state sensing apparatus and a head protecting apparatus of an ink jet printer.

Typically, a printer adopting a wire dot method, a thermal transfer method, or an ink jet method uses a unique recording head in a method of forming an image on a recording medium such as a paper sheet or an OHP (Over Head Project) film. The recording head of the ink jet printer among the above-described printers has a plurality of nozzles formed with a fine ejection hole for ink ejection. The ink in the nozzles is heated and expanded by a heating element provided corresponding to each nozzle, so that the ink is injected outside the nozzle and attached to the recording medium.

Accordingly, the ink jet printer selectively heats the nozzles of the recording head in correspondence with the image to be recorded, and ejects ink in the nozzles to form an image on the recording medium. At this time, the driving of the nozzle is controlled by the head driving device.

The head driving apparatus includes a head driving unit for controlling a switching unit for shutting off or connecting a power supply path of a heating element according to a head driving signal supplied from a control unit of an inkjet printer, And a plurality of heating elements corresponding to the plurality of driving transistors and the plurality of nozzles. When the driving transistor is turned on, the power supply unit supplies power from the power supply unit to the power supply unit, And a heating unit for heating the nozzle.

1 is a detailed block diagram of a conventional head driving apparatus having the above-described configuration. The head driving apparatus shown in Fig. 1 is composed of first to fourth head driving apparatuses 10, 16, 22, and 28. [ The first to fourth head driving devices 10, 16, 22, and 28 receive the head driving signals I ₁ to I _n input from the control unit.

Here, only one of the signals from the head driving signals I ₁ to I _n is an enable signal so that the head driving signals I ₁ to I _n typically drive only one heating element in one head driving device at the same time.

The head driving signals I ₁ to I _{n are} input to the first to fourth head driving devices 10, 16, 22 and 28 in parallel. Thus, the number of the maximum heating elements that the first to fourth head driving devices 10, 16, 22, and 28 of FIG. 1 can simultaneously drive is four.

Hereinafter, the first to fourth head driving devices 10, 16, 22 and 28 are constructed in the same manner, so that only the structure and operation of the first head driving device 10 will be described in detail.

The head driving signals I ₁ to I _n are input to the head driving unit DEC 1 of the first head driving unit 10. The head drive (DEC1) is a decoder, etc., and outputs the control signals Q ₁ to Q _m to control the switching unit 12 according to the signal from the I _n I _1. The PORB signal input to the chip enable terminal CE of the head driver DEC1 is a power-on reset signal. The OEAB and OEBB signals are signals for controlling the heating element for heating the odd nozzle and the heating element for heating the superior nozzle in the output of the head driving unit DEC1, respectively.

Output Q ₁ to Q _m of the head drive (DEC1) is inputted to the switching unit 12. The switching unit 12 is composed of driving transistors Q ₁₁ to Q _1m . The bases of the driving transistors Q ₁₁ to Q _1m receive the outputs Q ₁ to Q _m of the head driving unit DEC ₁ . The emitters of the driving transistors Q ₁₁ to Q _1m are grounded and the collectors are connected to the heating elements of the heating unit 14, respectively. Accordingly, when any one of the driving transistors Q ₁₁ to Q _1m is turned on, the corresponding heating element of the heating unit 14 is grounded.

The heating unit 14 is composed of heating elements R _H11 to R _H1m . One side of the heating element (R _H11 to R _H1m) are respectively connected to the collector of said driver transistor (Q ₁₁ to Q _1m), one side of the other side are the resistance (R _COM1) of the heating element (R _H11 to R _H1m) Lt; / RTI > The other side of the resistor R _COM1 is connected to the power source V _H. Yiettara power (V _H) is supplied to the power supply (V _H) to the resistance (R _COM1) heating elements _(H11 to R _H1m R) connected in parallel to the resistance via the (R _COM1). The resistor R _COM1 is a fusible resistor, and when the overcurrent is inputted through the power source V _H , the resistance value becomes infinite, thereby blocking the power source V _H from being input to the heating element. At this time, it is said that the resistance value of the fusible resistor becomes infinite.

As described above, in the conventional head driving device, a fusible resistance is used to protect a head composed of nozzles. However, the fusible resistance only protected the head from overcurrent flowing from the power supply. Therefore, the head can not be protected from damage of the head driving device. That is, when the driving transistor of the head driving device is SHORT, the heating element corresponding to the driving transistor is overheated. As a result, the nozzle corresponding to the heating element was damaged. Damage to the nozzle as described above has a problem of causing nozzle dropout.

In addition, when the head is damaged as described above, the user simply recognizes the damage of the head and replaces the head. At this time, the head drive was still damaged, so that even the new head was damaged.

As described above, the conventional inkjet printer can not protect the head from the damage of the head driving device. In addition, the user can not know the damage of the head driving device, and thus the damage of the new head can not be prevented.

Accordingly, an object of the present invention is to provide a head driving device steady state detecting device and a head protecting device that protects a head from damage to a head driving device, and informs a user when an abnormality occurs in the head driving device.

1 is a detailed circuit diagram of a conventional head driving device,

FIG. 2 is a block diagram of a head driving apparatus steady state detecting apparatus according to a preferred embodiment of the present invention;

Fig. 3 is a detailed circuit diagram of the head driving device of Fig. 2,

FIG. 4 is a detailed circuit diagram of the head driving device sensing unit of FIG. 2,

5 is a waveform diagram of the emitter voltage and the sensing voltage of the driving transistor of FIG. 3,

FIG. 6 is a flow chart according to the processing program of the control unit of FIG. 2;

FIG. 7 is a block diagram of a head protecting apparatus according to a preferred embodiment of the present invention,

8 is a detailed circuit diagram of the head protection circuit of FIG.

9 is a flowchart according to the processing program of the control unit of Fig. 7,

10 is a block diagram of a head protecting apparatus according to another preferred embodiment of the present invention.

Fig. 11 is a detailed circuit diagram of the head protection circuit of Fig. 10,

According to an aspect of the present invention, there is provided a head driving apparatus for searching a size of an emitter current of driving transistors of a head driving apparatus for driving a head to search whether a head driving apparatus is normally driven, The power supply is shut down, and an error of the head driving device is displayed to the user.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Many specific details are set forth in the description which follows and in the accompanying drawings in order to provide a more thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Further, the detailed description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

2 is a block diagram of an apparatus for detecting a steady state of a head driving apparatus according to a preferred embodiment of the present invention. The control unit 34 generates and outputs a head driving signal and displays the state of the head driving unit 36 on the display 40 in response to an interrupt signal. The head driving device 36 receives the emitter current from the head driving device 36 and senses whether the head driving device 36 is normally driven or not by receiving the emitter current from the head driving device 36. [ And a display unit 40 for displaying the state of the head driving unit 36 under the control of the control unit 34. [

Figure 3 shows the head drive 36 of Figure 2. The head driving device 36 connects the emitters of the driving transistors Q11 to Q4m of the conventional head driving device shown in Fig. 1 and the switching parts 12, 18, 24, and 30 to one node without being grounded All are the same except that. Hereinafter, a description of the structure of the head driving device 36 identical to the conventional one will be omitted.

A node to which the emitters of the driving transistors Q11 to Q4m are connected is referred to as a T-node. The emitter currents of the driving transistors Q11 to Q4m are summed and outputted through the T node.

If the head driving signals I ₁ to I _{n sequentially} heat the first to m- _th heating elements R _H11 to R _H1m from the first heating element R _H11 to the m- _th heating element R _H1m When the head driving signal (DEC1) is a signal output from the output Q ₁ to Q _m generates a signal which is the status above sequentially classic. In the head driving unit DEC1, the driving transistors Q ₁₁ to Q _{1 m} corresponding to the outputs Q ₁ to Q _m receive the signals generated in the high-potential state sequentially and conduct. When the driving transistors Q ₁₁ to Q _1m are turned on, the emitter voltage is high. This is shown in Fig. Since the driving transistors Q ₁₁ to Q _1m are sequentially turned on, the voltages of the driving transistors Q ₁₁ to Q _1m shown in FIG. 5 also sequentially rise to a high potential. The emitter current corresponding to the emitter voltage is summed and output to the T node. The emitter current output to the T-node is called a sensing current.

4 shows the head driving device sensing unit 38 of FIG. 2 in detail. The T node in FIG. 4 is the T node in FIG. The T-node is connected to a resistor (RS). Accordingly, the sensing current input from the T-node is output as the sensing voltage Vs1 by the resistor RS. As shown in FIG. 5, the sensing voltage Vs1 occurs at a high potential in a portion where the emitter voltage is high in potential.

The sensing voltage Vs1 is input to the non-inverting input terminal (+) of the comparator COM1. The power source Vcc is divided and input to the inverting input terminal (-) of the comparator COM1 by resistors RA and RB. The voltage input to the inverting input terminal (-) is referred to as a reference voltage. The reference voltage is given by the following equation (1).

Vref1 is a reference voltage. As described above, the reference voltage Vref1 is determined as the ratio of the resistances RA and RB. Accordingly, the resistance value of the resistors RA and RB is set so that the reference voltage Vref1 is equal to the sensing voltage Vs1 when one drive transistor is made conductive.

The comparator COM1 receives the reference voltage Vref1 and the sensing voltage Vs1 to generate a high potential output when Vs1 is greater than the reference voltage Vref1 and generates an output of low potential when the sensing voltage Vs1 is lower than the reference voltage Vref1 do. When the sensing voltage Vs1 is greater than the reference voltage Vref1, any one of the driving transistors of the head driving unit 36 is turned on. When the sensing voltage Vs1 is lower than the reference voltage Vref1, Is not conducted. The output of the comparator COM1 is called an interrupt signal. The interrupt signal is input to the control unit 34.

That is, after the controller 34 sequentially generates the head driving signal for driving the nozzle, if the interrupt signal detects the interrupt signal and generates the output of the low electric potential, it detects that the head driving device 36 is damaged, The head driving device 36 senses that it is normal.

On the other hand, FIG. 6 shows a flowchart according to the processing program of the control section 34. FIG. In step 42 of FIG. 6, the controller 34 applies the head driving signals I ₁ to I _m to the head driving unit 34 to drive the head. At this time, the head driving device 36 heats the nozzle according to the head driving signals I ₁ to I _m and outputs an emitter current. The emitter current is input to the head driving device sensing portion 38. The head driving unit sensing unit 38 senses the magnitude of the emitter current and generates an interrupt signal. In step 44, the controller 34 detects whether the interrupt signal has a high potential. At this time, if the interrupt signal has a high potential, the controller 34 performs step 50, and if the interrupt signal is low potential, step 46 is performed. In step (50), the controller 34 sets a normal flag and ends the flow.

On the other hand, in step (46), the control unit 34 sets the head driving device error flag. When the set is completed, the controller 34 performs step (48). In step (48), the control unit 34 transmits display data for displaying the head driving unit error to the head driving unit 36 to the display unit 40. The display device 40 displays a head driving device error occurrence according to the display data.

As described above, the present invention searches whether the head driving device 36 is normally driven and notifies the user when an abnormality occurs. Accordingly, the user can appropriately cope with the damage of the head driving device 36 and the damage of the head.

7 is a block diagram of a head protecting apparatus according to an embodiment of the present invention. The head protection device includes a control unit 54 for providing a head driving signal to the head driving unit 56 and receiving an interrupt signal and displaying an error of the head driving unit 56 on the indicator 52, A head driving device 56 for receiving ink from the head and for ejecting ink in the nozzle by heating the nozzle of the head and an emitter current of the head driving device 56 to detect whether the head driving device 56 is abnormal, A head protection circuit 60 for shutting down the power supply unit 58 for applying power to the head drive unit 56 when an abnormality occurs in the drive unit 56 and generating an interrupt signal; And a display unit 52 for displaying the information.

Since the head driving device 56 of FIG. 7 is the same as FIG. 3, detailed description is omitted. FIG. 8 shows the head protection circuit 60 of FIG. 7 in detail. The T node in FIG. 7 is connected to the T node in FIG. The emitter current input through the T node is output as the sensing voltage Vs2 through the sensing resistor RS. The sensing voltage Vs2 is expressed by the following equation (2).

In Equation (2), IE is the emitter current, RS is the sensing resistance, and Vs2 is the sensing voltage across the sensing resistor RS. The sensing voltage Vs2 is input to the non-inverting input terminal (+) of the comparator COM2. A reference voltage Vref2 is input to the inverting input terminal (-) of the comparator COM2. The reference voltage Vref2 is generated by dividing the voltage of the power source Vcc by the resistances RC and RD. The power source Vcc is connected to a resistor RC and the other side of the resistor RC is connected to one side of the resistor RD and the other side of the resistor RD is grounded. The reference voltage Vref2 applied to the point where the resistor RC and the resistor RD are connected is expressed by Equation 3 below.

As described above, the magnitude of the reference voltage Vref2 can be adjusted by the ratio of the resistor RC and the resistor RD. The setting of the adjustable reference voltage Vref2 as described above is performed as follows. As shown in Fig. 2, the conventional head driving apparatus includes four head driving units DEC1 to DEC4 corresponding to the four head driving units 10, 16, 22 and 28. [ Control unit 54 outputs to be enabled in time to generate a head drive signal I ₁ to I _m, the only one in the head drive signals I ₁ to I _m on the same time. Yiettara the four nozzles when the head drive signals I ₁ to I _m to receive the four head driving (DEC1 to DEC4), type is to be enabled in both heated. This is the maximum number of nozzles that can be driven. Thus, the sum of the emitter currents output from the four driving transistors becomes the maximum emitter current.

Here, a voltage obtained by adding the margin voltage to the voltage value obtained by converting the maximum emitter current to the voltage through the sensing voltage (RS) is set as the reference voltage.

That is, when the emitter voltage is larger than the voltage obtained by adding the margin voltage to the maximum emitter voltage, the head driving units DEC1 to DEC4 are damaged.

The set reference voltage Vref2 is input to the inverting input terminal (-) of the comparator COM2. The comparator COM2 generates a high potential output when the sensing voltage Vs2 is higher than the reference voltage Vref2 and generates a low potential output when the sensing voltage Vs2 of the comparator COM2 is lower than the reference voltage Vref2. The output of the comparator COM2 is provided to the control unit 56 as an interrupt signal. The output of the comparator COM2 is input to the inverter INV. The inverter INV inverts the output of the comparator COM2 and inputs it to the base of the PNP transistor QP. The collector of the PNP transistor QP is connected to the power source Vcc and the emitter is connected to the shutdown terminal of the power source unit 58. The PNP transistor QP is turned on when a low-potential voltage is applied to the base, and outputs the power Vcc to the emitter through a collector. The output of the emitter is input to the shutdown terminal of the power supply unit 58 to shut down the power supply unit 58. Accordingly, since the power supply Vcc is not applied to the head driving device 56, it is possible to prevent the head damage due to the abnormal state of the head driving device 56. [

On the other hand, FIG. 9 shows a flowchart of the processing program of the control section 54 for head protection. In step 62 of FIG. 9, the control unit 54 detects whether the interrupt signal is high. At this time, if the interrupt signal has a high potential, the control unit 54 performs step (68). If the interrupt signal is not the high potential, step (64) is performed. In step (64), the control unit 54 provides the head driving signal to the head driving unit 56. [ After the head driving signal is applied to the head driving device 56, the controller 54 detects whether the interrupt signal is at a high potential. At this time, if the interrupt signal has a high potential, the controller 54 performs step (68), and if the interrupt signal is at a low potential, the flow ends. In step (68), the control unit 54 sets the head driving unit error flag. When the set of the head driving apparatus error flag ends, the control unit 54 provides the indicator 52 with data for displaying the error of the head driving unit 56. [ The indicator 52 displays an error of the head driving device 56.

A block diagram of a head protecting apparatus according to another embodiment of the present invention for protecting the head by disabling the head driving units DEC1 to DEC4 of the head driving unit 56 only without shutting down the power supply unit 58 Is shown in Fig. The head protecting apparatus includes a heating unit 76 for heating a nozzle by receiving a head driving signal from a control unit 54, a head driving unit 72 for controlling a switching unit 74 for interrupting or connecting the path of the ground, A switching unit which is composed of a plurality of driving transistors and which disconnects or connects the path of the ground with the heating unit 76 under the control of the head driving unit 72 and connects the plurality of emitters to one node, A reference voltage Vref3 obtained by converting the emitter current into a voltage when the maximum number of nozzles that can drive the emitter current is driven, And a head protection circuit 80 for comparing the emitter voltage and disabling the head driver 72 if the emitter voltage is greater than the reference voltage Vref3.

The sensing resistor RS of the head protection circuit 80 receives the emitter current and converts it into a sensing voltage Vs3. The sensing voltage Vs3 is input to the inverting input terminal (-) of the comparator COM3. The non-inverting input terminal (-) of the comparator COM3 distributes the power source Vcc to the resistors RE and RF and supplies the emitter currents when the maximum nozzle that can be driven by the head driving unit 72 is driven. And the set reference voltage is applied. The comparator COM3 generates an output of a high potential when the reference voltage Vref3 is higher than the sensing voltage Vs3 and generates an output of a low potential when the reference voltage Vref3 is lower than the sensing voltage Vs3. The output is input to the chip enable terminal CE of the head driver 72. [ The chip driver terminal CE of the head driver 72 is disabled when a signal having a low potential is input. The normal head driver 72 receives the PORB signal at the chip enable terminal CE. Thus, the buffer B is connected between the PORB signal and the disable signal. Therefore, it is possible to prevent the PORB signal and the output of the comparator COM3 from interfering with each other.

As described above, according to the present invention, when an abnormality occurs in the head driving apparatus, the abnormality of the head driving apparatus is displayed to the user so that the user can recognize the abnormality of the head driving apparatus. Thereby, there is an advantage that the user can appropriately cope with the abnormality of the head driving device.

Further, when an abnormality occurs in the head driving apparatus, the power input to the head driving apparatus is cut off or the head driving apparatus is disabled. Therefore, there is an advantage that the head can be prevented from being damaged due to the damage of the head driving device.

Claims (9)

A head drive steady state sensing device comprising: And searching for the magnitude of the emitter current of the driving transistors of the head driving device occurring when the head is driven to search for whether the head is normally driven. A head drive steady state sensing device comprising: A resistor for converting the magnitude of the emitter current of the driving transistors of the head driving device, A reference voltage set to a magnitude obtained by converting a voltage applied to the resistor and an emitter current when one nozzle is driven to a voltage is received and if the voltage applied to the resistor is smaller than the reference voltage, A comparator for generating an interrupt signal, A display device for receiving display data indicating an abnormal state of the head driving device and displaying an abnormal state of the head driving device, A signal for driving one of the nozzles is provided to the head driving apparatus, and an interrupt signal of the comparator is received. When the interrupt signal indicates an abnormal state, the head driving apparatus is judged to be in an abnormal state and an abnormal state of the head driving apparatus is displayed And a control unit for providing the display data to the display unit. A head drive steady state sensing device comprising: A resistor for converting the magnitude of the emitter current of the driving transistors of the head driving device, A reference voltage set to a magnitude obtained by converting a voltage applied to the resistor and an emitter current when a maximum nozzle driveable by the head driving device is driven into a voltage is inputted and if a voltage applied to the resistor is greater than a reference voltage, A comparator for generating an interrupt signal indicating an abnormal state of the driving apparatus, A display device for receiving display data indicating an abnormal state of the head driving device and displaying an abnormal state of the head driving device, And a controller for judging that the interruption signal indicates an abnormal state and providing display data indicating an abnormal state of the head driving device to the display unit when it is determined that the head driving device is in an abnormal state, . A head protection device comprising: A plurality of heating elements are provided to heat the nozzles to spray ink in the nozzles and to have a plurality of driving transistors to cut off or connect the power supply path of the heating elements and to supply a plurality of head driving signals A head driving device for controlling a power supply path by conducting or not conducting the driving transistor in accordance with a received head driving signal; A power supply unit for applying power to the head driving apparatus, A resistor for converting the magnitude of the emitter current of the driving transistors of the head driving device into a voltage, A reference voltage set to a magnitude obtained by converting a voltage applied to the resistor and an emitter current when one nozzle is driven to a voltage is received and if the voltage applied to the resistor is smaller than the reference voltage, A comparator for generating an interrupt signal, A signal for driving one nozzle is supplied to the head driving device, and an interrupt signal of the comparator is then received. When the interrupt signal indicates an abnormal state, it is determined that the head driving device is in an abnormal state, and power is supplied to the head driving device And a control unit for shutting down the power supply unit. The head protecting apparatus according to claim 4, A display device for receiving display data indicating an abnormal state of the head driving device and displaying an abnormal state of the head driving device, Further comprising a control unit for determining that the head driving unit is in an abnormal state when the interrupt signal indicates an abnormal state and providing display data for indicating an abnormal state of the head driving unit to the display unit. 5. The apparatus of claim 4, And generates an interrupt signal indicating an abnormal state when the voltage is higher than the emitter voltage at the time of maximum nozzle driving. A head protection device comprising: A plurality of heating elements are provided to heat the nozzles to spray ink in the nozzles and to have a plurality of driving transistors to cut off or connect the power supply path of the heating elements and to supply a plurality of head driving signals A head driving device for controlling a power supply path by conducting or not conducting the driving transistor in accordance with a received head driving signal; A power supply unit for applying power to the head driving apparatus, A resistor for converting the magnitude of the emitter current of the driving transistors of the head driving device into a voltage, A reference voltage set to a magnitude obtained by converting a voltage applied to the resistor and an emitter current when one nozzle is driven to a voltage is received and if the voltage applied to the resistor is smaller than the reference voltage, A comparator for generating an interrupt signal, A controller for providing a signal for driving one nozzle to the head driving device and receiving an interrupt signal of the comparator and determining that the head driving device is in an abnormal state when the interrupt signal indicates an abnormal state, Wherein the head protection device comprises: The head protecting apparatus according to claim 7, A display device for receiving display data indicating an abnormal state of the head driving device and displaying an abnormal state of the head driving device, Further comprising a control unit for determining that the head driving unit is in an abnormal state when the interrupt signal indicates an abnormal state and providing display data for indicating an abnormal state of the head driving unit to the display unit. 8. The apparatus of claim 7, And generates an interrupt signal indicating an abnormal state when the voltage is higher than the emitter voltage at the time of maximum nozzle driving.