KR20080057057A - Print head driver for image forming device - Google Patents

Abstract

A heating element driver is provided to prevent malfunction caused by initialization of various registers processing data signals due to noise while a printer is in operation. A heating element driver(300) driving a plurality of heating element groups included in a print head by a first data signal for selecting the group to be heated and a second data signal for selecting a heating element of the selected group, which comprises a data processing unit(330,360) converting the first and second data signals into parallel type signals, a driving signal generating unit(370) generating a driving signal for driving the selected heating elements based on the parallel type signals, a heating element driving unit(380) driving the selected heating elements according to the driving signal, and a reset filter receiving a reset signal to initialize a logic circuit that converts the type of the first and second data signals and removing noise from the reset signal and outputting the noise-removed signal.

Description

 Print head driver for image forming apparatus {Print head driver for image forming device}

1 is a block diagram showing a configuration of a heating element driving apparatus of a print head according to the prior art.

FIG. 2 is a timing diagram of an input signal input to the heating element driving apparatus shown in FIG. 1.

3 is a block diagram showing a configuration of a heating element driving apparatus of a print head according to an embodiment of the present invention.

4 is a timing diagram of an input signal input to the reset filter shown in FIG. 4.

The present invention relates to an inkjet image forming apparatus, and more particularly, to an apparatus for driving heating elements included in a print head of an image forming apparatus.

In general, an inkjet image forming apparatus refers to an apparatus for forming an image by ejecting ink from a print head reciprocated in a direction perpendicular to a conveying direction of the recording medium at a predetermined distance from the recording medium. As such, a printing method of printing an image by injecting ink onto the recording medium while being transferred in a direction perpendicular to the conveying direction of the recording medium is called a shuttle method. The shuttle-type print head is provided with a nozzle unit provided with a plurality of nozzles for ejecting ink.

Recently, an array head structure is used to print images at a high speed by using a print head having the same length as the width of a recording medium to be printed for high speed and high quality images. Many heads are being developed. Since the print head of the array head structure has a large number of nozzles included in the print head, the number of heating elements provided corresponding to the furnaces also increases.

In general, since a large amount of power is consumed to drive a large number of heating elements, a time division driving method is used in which the heating elements are sequentially driven. The time-division driving scheme selects a group to be driven from among the plurality of groups by using address data (ADDR) and belongs to the selected group by using primitive data (P_Data). Select heating elements to be driven among the heating elements.

FIG. 1 is a block diagram showing the configuration of a conventional heating element driving apparatus 100, and FIG. 2 is a timing diagram of an input signal input to the heating element driving apparatus 100 shown in FIG. As shown in FIG. 1, the conventional heating element driving apparatus 100 includes a primitive data (P_Data) processor 130 and an n bit shift register 140 including an m bit shift register 110 and an m bit latch 120. ), an address data (ADDR) processing unit 160 composed of n bit latch 150, other function performing units m ㅧ a drive signal generator 170 composed of n AND gate arrays, and m ㅧ The heating element driver 180 includes an n-bit transistor or a FET array. The heating element driving apparatus 100 shown in FIG. 1 is a case where time division driving is performed by dividing m 그룹 n heating elements into n groups so that m heating elements are included in one group.

The nozzles to be driven corresponding to the image to be recorded are selected by a main controller (main controller) of the image forming apparatus, and the address data ADDR and the primitive data P_Data related to the selected nozzles are heated in the print head. Transfer to the drive. At this time, the address data and the primitive data are configured as serial signals and transmitted so as to reduce the number of data lines between the main controller and the print head.

  The m bit shift register 110 and the n bit shift register 130 respectively receive and store the primitive data P_Data and the address data ADDR transmitted from the main controller in synchronization with the clock signal. The m bit latch 120 and the n bit latch 140 respectively store the m bit primitive data P1, P2,... stored in the m bit shift register 110 and the n bit shift register 130 when a load signal is input. .., Pm and the n bit address data A1, A2, ..., An are latched.

The driving signal generating unit 170 is composed of an array of m ㅧ n AND gates, and when the strobe signal for ejecting ink is input from each nozzle, the m bit latch 120 and n The primitive data (P1, P2, ..., Pm) and address data (A1, A2, ..., An) latched in the bit latch 140 are input to each AND gate, and each AND The output signal of the AND gate is output as the drive signal of the nozzle.

The heating element driver 180 turns on a transistor for supplying power to the heating element for heating the nozzle according to the driving signal input from the driving signal generator 170. When the transistor is turned on, current is supplied to the heating element to eject ink from the nozzle.

The heating element driving apparatus includes a heating element driving apparatus 100 in addition to the clock signal, the serial data (address data ADDR and primitive data P_Data), and the load signals input as the latches 120 and 140. A reset signal for initializing the various registers 110 and 130 of FIG. However, when the heating device driving apparatus 100 is exposed to static electricity during printing and is affected by EMS (Electro-Magnetic Susceptibility), noise may flow into the reset signal line. Alternatively, when the number of heating elements driven simultaneously increases, a noise component is increased in the heating element driving apparatus 100 because a large amount of current is consumed for several short periods of several hundred nsec (nano second). This noise may flow into the reset signal line. When noise is introduced into the reset signal line as described above, various registers 110 and 130 for processing the printing data may be initialized due to the noise, thereby causing the heating element driving apparatus 100 to malfunction, resulting in deterioration of the printed image. This is a problem.

Accordingly, a technical object of the present invention is to provide a heating element driving apparatus of a print head that receives a data signal for selecting a heating element to be driven to drive the heating element, and processes the data signal due to noise during a printing operation. It is to provide a heating element driving device that can prevent the malfunction of the driving device is initialized by various registers.

The heating element driving apparatus according to the present invention for solving the above technical problem is the first data signal for selecting a group to drive the heating element divided into a plurality of groups included in the print head and the heating element belonging to the selected group An apparatus for driving by using a second data signal for selecting a heating element to be driven, comprising: a data processor for converting the first and second data signals input in a serial signal format into a parallel format; A drive signal generator for generating a drive signal for driving the selected heating element based on the first and second data signals converted into the parallel format; A heating element driver for driving the selected heating elements according to the generated driving signal; And a reset filter provided in the data processor to receive a reset signal for initializing a logic circuit for converting the format of the first and second data signals, and to remove noise and output the reset signal.

After the state of the input reset signal is changed, the reset filter may remove noise of the input reset signal by changing the state of the output reset signal only when the changed state is maintained for a predetermined time or more.

In addition, the reset filter uses a shift register that uses the same clock signal as that of the data processing unit, and when the changed state of the input reset signal is kept constant while a predetermined number or more of the clock signals are applied, The state of the output reset signal can be changed.

The driving signal generator may initialize the driving signal according to the reset signal.

The driving signal generation unit may generate the driving signal based on the first and second data signals converted into the parallel form using a plurality of AND gates corresponding to each of the plurality of heating elements. The driving signal may be initialized according to the reset signal by directly applying the reset signal to each of the plurality of AND gates.

Hereinafter, a heating device driving apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram showing the configuration of a heating element driving apparatus according to an embodiment of the present invention. Referring to FIG. 3, the heating device driving apparatus 300 includes a primitive data (P_Data) processing unit 330, an n bit shift register 340, and an n bit latch including an m bit shift register 310 and an m bit latch 320. An address data (ADDR) processor 360 composed of 350, a drive signal generator 370 composed of an m ㅧ n AND gate array, an m ㅧ n bit transistor, or a FET (Feild Effect Transistor). The heating element driver 380 and the reset filter 390 are configured as an array. The primitive data processing unit 330, the address data processing unit 360, and the heating element driving unit 380 are similar to those of the heating element driving apparatus 100 according to the prior art. The heating element driving apparatus 300 shown in FIG. 3 is a case where time division driving is performed by dividing m 하여 n heating elements into n groups so that m heating elements are included in one group.

First, nozzles to be driven corresponding to an image to be recorded are selected by a main controller (main controller) of the image forming apparatus, and address data ADDR and primitive data P_Data related to the selected nozzles are stored in the print head. Transfer to heating element drive. At this time, the address data and the primitive data are configured as serial signals and transmitted so as to reduce the number of data lines between the main controller and the print head.

The primitive data processor 330 is composed of an m bit shift register 310 and an m bit latch 320. The m bit shift register 310 receives m bit primitive data P_Data in the form of a serial signal from the main controller in synchronization with the clock signal CLOCK, and converts the m bit primitive data into a form of a parallel signal. When the LOAD signal is input, the m bit latch 320 latches the m bit primitive data P1, P2,..., Pm converted into parallel signals.

The address data processor 360 includes an n bit shift register 340 and an n bit latch 350. The m bit shift register 340 receives n bit address data ADDR from the main controller in the form of a serial signal in synchronization with the clock signal CLOCK, and converts the m bit shift register 340 into a parallel signal. When the LOAD signal is input, the n bit latch 350 latches the n bit address data A1, A2,... An converted in parallel signal form. In addition to the shift registers 310 and 340 and the latches 320 and 350, the heating signal driving device 300 processes a data signal transmitted from the main controller and supplies a memory, various kinds of internal memory to the driving signal generator 370. It may further include a sensor.

Conventionally, various registers, latches, memories, sensors, and the like are directly initialized by externally reset signals. Therefore, when noise flows into the reset signal line, a register or latch is unintentionally initialized due to the noise, which often causes a malfunction of the heating signal drive device.

Therefore, in the present invention, the noise of the reset signal RESET input from the reset filter 390 is removed, and various registers, latches, and the like are initialized by the reset signal Reset_Out from which the noise is removed. The noise removal process of the reset filter 390 will be described later.

The drive signal generator 370 is composed of an array of m ㅧ n AND gates. When the strobe signal for ejecting ink is input from each nozzle, the mbit latch 320 and n The primitive data (P1, P2, ..., Pm) and address data (A1, A2, ..., An) latched in the bit latch 350 are input to the respective AND gates, and each AND The output signal of the AND gate is output as the drive signal of the nozzle. As described above, the address data A1, A2, ..., An are data for selecting a group to be driven corresponding to an image to be recorded from among n groups in which a plurality of heating elements are divided, and primitive data ( P1, P2, ..., Pm) are data for selecting a heating element to be driven among m heating elements belonging to one group. When the address data corresponding to the selected group and the primitive data corresponding to the selected heating element are turned on, when the strobe signal indicating ink ejection is turned on, the selected group is selected. The output value of the AND gate corresponding to the heating element will also be ON. In this case, the driving signal generator 370 directly applies the reset signal RESET to the AND gate so that the driving signal is initialized by the reset signal. In general, when power is supplied to the heating element driver, a reset signal is applied to initialize logic circuits such as various registers inside the heating element driver. By doing so, it is possible to prevent abnormal operation such as driving of heating elements in the initialization process of the printer system. As shown in FIG. 3, the driving signal generator 370 directly inputs an externally input reset signal to each AND gate. Because the power supply unit connected to the transistor array for driving the heating elements provided in the heating element driver 380 has a relatively high capacitance characteristic, the heating element is normally operated even after a momentary change of the driving signal due to noise. This is because the influence of noise is negligible because it can be operated.

However, in another embodiment, an output reset signal Reset_Out from which noise is removed from the reset filter 390 may be applied to each AND gate of the driving signal generator 370.

The heating element driver 380 turns on a transistor for supplying power to the heating element for heating the nozzle according to the driving signal input from the driving signal generator 370. When the transistor is turned on, current is supplied to the heating element to eject ink from the nozzle.

Now, the operation of the reset filter 390 which removes and outputs noise of the reset signal RESET input from the outside will be described in detail.

The reset filter 390 may remove noise by changing the state of the reset signal Reset_Out output when the changed state is maintained for a predetermined time or more after the state of the reset signal RESET is changed. According to an exemplary embodiment of the present invention, noise of the reset signal RESET may be removed by using the clock signal used in the heating signal driving apparatus 300.

 The reset filter 390 has a predetermined bit shift register built into the circuit, and after the state of the input reset signal RESET is changed, the changed state remains constant while a predetermined number or more of the clock signals CLOCK are input. The reset signal Reset_Out output to the controller may be designed to be changed. In general, when a reset signal is applied, the reset signal is normally normal when the reset signal is high.

4 is a timing diagram illustrating a clock signal CLOCK, an input reset signal RESET, and an output reset signal Reset_Out for explaining an operation of the reset filter 390 according to an exemplary embodiment of the present invention. As shown in FIG. 4, the reset filter 390 is reset only when at least five clock signals CLOCK are applied after the state of the reset signal RESET is changed from high to low. The state of the output reset signal Reset_Out of the filter 390 is changed to low. When the input reset signal RESET is changed back to the high state, the output high reset signal (Reset_Out) is maintained after the high state is maintained during the input of the five clock signals CLOCK. ) State is changed to High. However, when the state of the reset signal (RESET) is changed to a low state due to the influence of noise, and then changes to the high state again after three clock signal (CLOCK) signals are input, it is in a low state. Since is not held while the five clock signals (CLOCK) is input, the state of the output reset signal (Reset_Out) does not change to LOW. Therefore, the reset filter 390 may prevent the instantaneous change of the state of the reset signal RESET due to noise and the initialization of various registers in the heating signal driving device 300.

As described above, the heating element driving apparatus 300 according to an embodiment of the present invention removes noise from a reset signal RESET for initializing logic circuits such as various registers and latches, and resets the noise to be removed. By initializing the logic circuits using a signal, the logic circuits of the heating element driving apparatus 300 may be initialized by noise during a printing operation, thereby preventing the heating element driving apparatus 300 from malfunctioning.

In addition, the heating element driving apparatus 300 according to an embodiment of the present invention directly applies a reset signal RESET to an AND gate for generating a driving signal, thereby causing the inside of the heating element driving apparatus 300 to be reduced. When the logic circuits are initialized, the driving signal is also initialized together. By doing so, it is possible to prevent the heating element from being abnormally operated in the initialization process of the heating element driving device 300.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

The best embodiment has been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the heating element driving apparatus according to the present invention removes noise included in a reset signal for initializing logic circuits such as various registers inside the apparatus for driving the plurality of heating elements included in the print head, thereby removing the noise. By initializing the logic circuits by removing the reset signal, the logic circuits are prevented from being initialized under the influence of noise during the printing operation, thereby preventing malfunction of the print head.

Claims (5)

Driving by using a first data signal for selecting a group to drive heating elements divided into a plurality of groups included in the print head and a second data signal for selecting heating elements to be driven among heating elements belonging to the selected group. In the apparatus, A data processor converting the first and second data signals inputted in a serial signal format into a parallel format; A drive signal generator for generating a drive signal for driving the selected heating element based on the first and second data signals converted into the parallel format; A heating element driver for driving the selected heating elements according to the generated driving signal; And And a reset filter provided in the data processor and configured to receive a reset signal for initializing a logic circuit for converting the format of the first and second data signals, and to remove and output noise. Drive system. The method of claim 1, wherein the reset filter And the noise of the input reset signal is removed by changing the state of the output reset signal only when the changed state is maintained for a predetermined time or more after the state of the input reset signal is changed. The method of claim 1, wherein the reset filter By using a shift register using the same clock signal as the clock signal of the data processing unit, the state of the output reset signal is changed when the changed state of the input reset signal is kept constant while the predetermined number of clock signals are applied. Heating element drive, characterized in that to be changed. The method of claim 1, wherein the driving signal generation unit Heating element driving apparatus, characterized in that for initializing the drive signal in accordance with the reset signal. The method of claim 4, wherein the driving signal generator The driving signal is generated based on the first and second data signals converted in the parallel form by using a plurality of AND gates corresponding to each of the plurality of heating elements, and the reset signal is generated by the plurality of reset gates. And directly driving the driving signal according to the reset signal by directly applying to each of the AND gates.

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