This application claims priority to Japanese Patent Application No. 2003-054011 filed Feb. 28, 2003 which is hereby expressly incorporated by reference herein in its entirety.
1. Technical Field of the Invention
The present invention relates to a driving device of an ink-jet print head, a control method of the driving device, and a liquid drop discharge apparatus.
2. Description of the Related Art
The overview of a head unit and a driving device thereof for an ink-jet liquid drop discharge apparatus will be described with reference to
A latch signal LAT, which is obtained by delaying the print timing signal PTS for a predetermined amount of time, is supplied to the driving signal generator 915 from the high-rank unit. In addition, a static voltage VH of about 30 V is applied to the driving signal generator 915 and becomes a power source for a driving signal. The driving signal data input from a data bus is digital-to-analog (D/A) converted by the driving signal generator 915 and is output as the driving signal Vout.
Meanwhile, as shown in
An object substrate on which liquid drops are discharged using the aforementioned ink-jet liquid drop discharge apparatus has become larger. With the large-sized substrate object, the number of head units or nozzles tends to increase. For this reason, there are drawbacks such as an increase in power consumption of a driving device. In particular, liquid drop discharge apparatuses for industrial uses generally include at least ten head units for improving processing efficiency. In this case, however, the amount of radiated heat also increases with the increase in power consumption. Such increases in power consumption and the amount of radiated heat become a serious problem when liquid drops are uniformly and consecutively discharged onto the object substrate (so-called, application of liquid drops to the entire surface of a region).
The present invention has been made to address the above problem with the prior art. It is therefore an object of the present invention to provide a driving device of an ink-jet print head, a control method of the driving device, and a liquid drop discharge apparatus, which have low current consumption and a small amount of radiated heat.
To address the problem and attain the object described above, according to the present invention, there is provided a driving device of an ink-jet print head that discharges liquid drops through a plurality of nozzles. The driving device comprises a data storage unit, which stores a data block for liquid drop discharge; a data determination unit, which determines the stored data block; a shift register, which outputs the determined data block to the ink-jet print head; and a clock signal generation unit, which generates clock signals for driving the shift register. The data determination unit determines whether the data block has a predetermined array. When the data block has the predetermined array, the clock signal generation unit stops generating the clock signals. The shift register outputs the data block having the predetermined array to the ink-jet print head. Thus, when the data block output to the print head has the predetermined array, the clock signal generation unit stops generating the clock signals. Also, the shift register does not operate based on the clock signals. At this time, the shift register outputs the data block having the predetermined array, which is prefixed (i.e., pre-selected) data, to the print head. As a result, it is possible to reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register.
According to a preferred aspect of the present invention, the data determination unit determines whether all the data items of the data block are discharge data items for which liquid drops are to be discharged or non-discharge data items for which liquid drops are not to be discharged, the clock signal generation unit stops generating the clock signals when all the data items of the data block are the discharge data items or the non-discharge data items, and the shift register outputs the discharge data items or the non-discharge data items to the ink-jet print head when the generation of the clock signals is stopped. Thus, when all the data items of the data block are the discharge data items or the non-discharge data items, the clock signal generation unit stops generating the clock signals. Also, the shift register does not operate based on the clock signals. At this time, the shift register outputs the discharge or non-discharge data block having the prefixed array, which is predetermined data, to the print head. As a result, it is possible to reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register.
According to a preferred embodiment of the present invention, the plurality of nozzles are provided in every block having a predetermined number of the nozzles, and a plurality of data determination units are provided in the corresponding blocks. Thus, even when the number of nozzles is large, the driving of the shift register can be controlled for each block. As a result, it is possible to reliably reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register.
According to the present invention, there can be provided a control method of a driving device of an ink-jet print head that discharges liquid drops through a plurality of nozzles. The control method comprises a data storage step of storing a data block for liquid drop discharge; a data determination step of determining the stored data block; a data output step of outputting the determined data block to the ink-jet print head via a shift resistor; and a clock signal generation step of generating clock signals for driving the shift register. The data determination step comprises determining whether the data block has a predetermined array, and the clock signal generation step comprises stopping the generation of the clock signals when the data block has the predetermined array. Thus, when the data block output to the print head has the predetermined array, the clock signal generation unit stops generating the clock signals. The shift register does not operate based on the clock signals. At this time, the shift register outputs the data block having the predetermined array, which is prefixed data, to the print head. As a result, it is possible to reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register.
According to a preferred embodiment of the present invention, the data determination step comprises determining whether all the data items of the data block are discharge data items for which liquid drops are to be discharged or non-discharge data items for which liquid drops are not to be discharged, the clock signal generation step comprises stopping the generation of the clock signals when all the data items of the data block are the discharge data items or the non-discharge data items, and the data block output step preferably comprises outputting the discharge data items or the non-discharge data items to the ink-jet print head when the generation of the clock signals is stopped. Thus, when all the data items of the data block are the discharge data items or non-discharge data items, the clock signal generation step stops generating the clock signals. Also, the shift register does not operate based on the clock signals. At this time, the shift register outputs the discharge or non-discharge data block having the predetermined array, which is prefixed data, to the print head. As a result, it is possible to reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register.
According to the present invention, there can be provided a liquid drop discharge apparatus comprising: a driving device of an ink-jet print head as described above, and a print head having a control unit that drives the plurality of nozzles based on the data block output from the driving device. This makes it possible to reduce the power consumption and the amount of radiated heat that are caused by the driving of the shift register. As a result, it is possible to achieve a liquid drop discharge apparatus that reduces the power consumption thereof and the amount of radiated heat while using a conventional print head.
a)–6(h) are timing charts for data transmission according to prior art.
a)–7(h) are timing charts for data transmission according to the first embodiment of the present invention.
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, the overview of a driving device of an ink-jet print head according to a first embodiment of the present invention will be described with reference to
A latch signal LAT, which is obtained by delaying the print timing signal PTS for a predetermined amount of time, is supplied to the driving signal generator 115 from the high-rank unit. In addition, a static voltage VH of about 30 V is applied to the driving signal generator 115 and becomes a power source for a driving signal. The driving signal data input from a data bus is digital-to-analog (D/A) converted by the driving signal generator 115 and is output as the driving signal Vout.
A data determination unit 112 determines the contents of a stored data block. The operation of the data determination unit 112 will be described in detail later. A clock signal generation unit 114 generates an internal shift clock signal ILCK2 for driving the shift register 113 in the driving device 110. The shift register 113 converts a parallel data block into a serial data block SDATA and outputs the serial data block SDATA to the head unit 150.
Next, the schematic configuration of the head unit 150 will be explained. The head unit 150 is provided with a shift register 151 to which the serial data block SDATA is input.
The head unit 150 also includes a nozzle driving unit 154 that has actuators for driving nozzles (not shown) communicating with a plurality of liquid drop containers and a selector 153 that selects a nozzle to be driven. A data storage unit, i.e., a latch circuit 152 for storing the serial data block SDATA transmitted from the driving device 110 is provided at the preceding stage of the selector 153. The driving signal Vout transmitted from the driving device 110 is applied to the selector 153. Driving information for each nozzle is selectively applied to the selector 153. In nozzle driving unit 154, actuators to which the driving signal Vout is supplied are driven, thereby discharging liquid drops from desired nozzles.
Assuming that an external shift clock signal SCLK in sixty four nozzle heads has a frequency of 1 MHz, the latch signal LAT input to the latch circuit 152 is activated in synchronization with the driving signal Vout during a period of more than 64 μs. During this latch period, a serial data block SDATA for the next latch period is latched in the latch circuit 152 through the shift register 151 and is input to the selector 153.
According to the operating timing in the above configuration, when the latch signal LAT is activated, the driving signal Vout and a serial data block SDATA before one latch period are input to the head unit 150 from the driving device 110. In the head unit 150, a corresponding nozzle is driven based on transmitted various signals or a serial data block SDATA and liquid drops are discharged to a predetermined region of a media to be printed.
a) is a block diagram schematically showing the liquid drop discharge apparatus 100 (
A print timing signal PTS corresponding to the discharge timing of liquid drops is input to a control signal input unit 205. In addition, the print timing signal PTS is input to the latch circuit 111 and a clock signal generation unit 114 via a timing control unit 206. The timing control unit 206 generates a latch signal LAT based on the input print timing signal PTS. The latch signal LAT is output to the driving signal generation unit 115 and the head unit 150 through the flexible flat cable FFC. The clock signal generation unit 114 generates the internal shift clock signal ILCK2 that is a shift clock of the shift register 113 and the external shift clock signal SCLK that is output to the head unit 150 through the flexible flat cable FFC.
In
The serial data block SDATA that is serially input from the driving device 110 is converted into a parallel data block by the shift register 151 and the parallel data block is stored in the latch circuit 152. The stored data block is selectively input to n selectors S1 to Sn, each of which is composed of an analog switch. The driving signal Vout output from the driving device 110 is input to the selectors S1 to Sn and is output to nozzles N1 to Nn only when selectively input data indicates a discharge state. In the nozzle driving unit 154, actuators to which the driving signal Vout is supplied are driven, and thus liquid drops are discharged from the corresponding nozzles.
The driving device 110 according to the first embodiment of the present invention will be described in more detail with reference to
a) to 6(h) are timing charts for data transmission according to the prior art.
Further, referring to the second column T2, all the rows N1 to N8 include discharge data (=1) represented by black dots. In the conventional art, the internal shift clock signal ILCK for the shift register 113 in the driving device 110 is generated at all times in such a case. Furthermore, referring to the last column T17, all the rows N1 to N8 include non-discharge data (=0) represented by white dots. In the conventional art, the internal shift clock signal ILCK for the shift register 113 in the driving device 110 is generated even in such a case. In other words, in the conventional art, the internal shift clock signal ILCK is generated at all times, irrespectively of the contents of a data block input to the shift register 113 of the driving device 110. For this reason, the shift register 113 of the driving device 110 operates at all times. As a result, the power consumption and the amount of radiated heat increase. These problems become serious when the ratio occupied by discharge data (=1) as shown in
a) to 7(h) are timing charts for data transmission according to the first embodiment of the present invention.
In the third column T15 from the last column, as can be seen from
As described above, in this embodiment, the data determination unit 112 determines whether all the data items of a data block are a discharge data block that discharge liquid drops or a non-discharge data block that do not discharge liquid drops. As apparent from the timing charts of
In this embodiment, the number of data determination units 112 is not limited to one. For example, a plurality of nozzles can be provided in every predetermined number of blocks and a plurality of data determination units 112 can be provided corresponding to the predetermined blocks. Thus, even when the number of nozzles is large, the driving of a shift register can be controlled for each block.
As a result, the power consumption caused by the driving of the shift register 113 and the amount of radiated heat can be certainly reduced. In summary, since data determination can be performed for each block, the number of patterns that can be determined increases. As a result, such data determination can be applied to any pattern other than discharge or non-discharge through all the nozzles. Thus, reductions in power consumption and the amount of radiated heat can be more effectively achieved.
Second Embodiment
Number | Date | Country | Kind |
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2003-054011 | Feb 2003 | JP | national |
Number | Name | Date | Kind |
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20020113832 | Kanematsu et al. | Aug 2002 | A1 |
Number | Date | Country |
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05-116282 | May 1993 | JP |
09-039272 | Feb 1997 | JP |
2002-264366 | Sep 2002 | JP |
Number | Date | Country | |
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20040223016 A1 | Nov 2004 | US |