JP2014117842A - Liquid droplet discharge device, liquid droplet discharge device control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten waiting time since a device is powered on until printing starts.SOLUTION: A liquid droplet discharge device includes: a piezoelectric element performing charging/discharging by applying a drive waveform to the piezoelectric element; and driving means for generating a fine drive waveform for prohibiting a nozzle from discharging ink even if being applied to the piezoelectric element. A current value of the fine drive waveform before a printing operation is generated to be larger than a current value of the fine drive waveform at a time of the printing operation.

Description

  The present invention relates to a droplet discharge device, a control method thereof, and a program.

  When printing is continuously performed with an inkjet printer, the temperature of the head and the temperature of the ink gradually increase due to the loss of the piezoelectric element of the head and the loss of the driving IC (Integrated Circuit). Further, due to the heat generated by the power source, electric circuit, various motors, etc. of the printer main body, the environmental temperature of the head also rises, causing the head temperature and the ink temperature to rise.

  For this reason, immediately after the printer is turned on and after printing is performed to some extent, the head and ink temperatures are different, and the print quality changes due to changes in the ink ejection characteristics. In order to minimize this change, the temperature of the head and ink is detected and correction is performed to change the drive waveform to an appropriate waveform, but the change in print quality cannot be made zero.

  Technology that starts printing after the head and ink temperatures have been raised in advance by performing fine driving that does not eject ink before printing starts in order to minimize this temperature change and improve printing quality. It has been known.

  Japanese Patent Application Laid-Open No. 2004-133867 aims to make the printed images have substantially the same color immediately after the start of printing and after printing several sheets from the start of printing. In addition, a technique is disclosed in which the drive element is driven with a cycle shorter than the drive cycle used for printing before printing is performed, and the temperature in the apparatus is increased by the heat generated by the drive circuit. It is also disclosed that the waveform used for driving before printing is a waveform in which ink is not ejected.

  However, if a process for increasing the temperature of the head and ink is newly added before the start of printing as in the technique disclosed in Patent Document 1, printing cannot be executed during this process. Therefore, there is a problem that the waiting time from the power-on to the start of printing becomes long.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and by reducing the time required for the temperature rise of the head and the ink, the waiting time from the power-on to the start of printing is shortened. An object is to provide a droplet discharge device.

  In order to solve the above-described problem, the droplet discharge device according to the first aspect of the present invention includes a piezoelectric element that charges and discharges by applying a drive waveform, and discharges ink from the nozzle even when applied to the piezoelectric element. And a driving unit that generates a fine driving waveform that is not generated, and the current value of the fine driving waveform before the printing operation is larger than the current value of the fine driving waveform during the printing operation. It is generated as follows.

  According to the present invention, the current flowing through the drive IC and the piezoelectric element when the fine drive waveform is applied is increased, and the amount of heat generated as a loss of each element is increased, so that the head and ink before the start of printing are added. Warm time can be shortened. Thereby, it is possible to obtain a droplet discharge device that can shorten the waiting time from power-on to the start of printing.

It is a figure which shows an example of the head drive waveform of the droplet discharge apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the drive waveform for heating before the printing operation of the droplet discharge apparatus which concerns on embodiment of this invention. It is a figure explaining the control circuit of the droplet discharge apparatus which concerns on embodiment of this invention. (A) Voltage of fine drive waveform, (b) Current of fine drive waveform, and (c) Fine during head heating before printing operation and during printing operation of the droplet discharge device according to the embodiment of the present invention. It is a figure explaining the power consumption of a drive waveform. It is a flowchart figure explaining operation | movement of the droplet discharge apparatus which concerns on embodiment of this invention.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified thru | or abbreviate | omitted suitably. The present invention relates to a fine driving waveform used for heating a droplet discharge head before printing.

  That is, the amount of heat generated is increased by increasing the current flowing through the piezoelectric element and the driving IC during fine driving and increasing the loss of each element. Specifically, the rise time and fall time until the voltage waveform of the fine drive waveform before the printing operation reaches a predetermined voltage value are shorter than the rise time and fall time of the fine drive waveform during the printing operation, respectively. It is characterized by that.

  The characteristics of the present invention described above will be described in detail with reference to the drawings. First, a head driving waveform of a droplet discharge device and a control circuit of the droplet discharge device according to an embodiment of the present invention will be described. FIG. 1 is a diagram illustrating an example of a head drive waveform of a droplet discharge device according to an embodiment of the present invention, and FIG. 3 is a diagram illustrating a control circuit of the droplet discharge device according to the embodiment of the present invention. is there.

  FIG. 1 shows the horizontal axis as time and the vertical axis as drive waveform. In FIG. 3, analog switches SW1 to SWN and piezoelectric elements C1 to CN are inserted in series between the drive waveform line and the ground (GND). The analog switches SW1 to SWN are ON / OFF controlled by outputs from the flip-flop circuit 1 and the latch circuit 2.

  When the analog switches SW1 to SWN are turned on by the outputs of the flip-flop circuit 1 and the latch circuit 2, a drive waveform is applied to the piezoelectric elements C1 to CN. When the analog switches SW1 to SWN are turned off, the application of the drive waveform to the piezoelectric elements C1 to CN is stopped.

  In FIG. 1, a waveform from time T0 to T1, which is a drive waveform for ejecting ink, and a waveform from time T1 to T2, which is a fine drive waveform for performing only stirring without ejecting ink, are generated in time series. Yes. In FIG. 3, the nozzles from which ink is ejected are turned on for the period from T0 to T1 in FIG. 1 and the drive waveforms are applied to the piezoelectric elements C1 to CN. .

  For nozzles that do not eject ink, the analog switches SW1 to SWN are turned on only during the period from T1 to T2 in FIG. 1, and a fine drive waveform is applied to the piezoelectric elements C1 to CN. Printing is executed by repeating this process.

  When the head is driven by ink ejection and fine driving, current flows from the piezoelectric elements C1 to CN via the analog switches SW1 to SWN during charging and discharging of the piezoelectric elements C1 to CN. At this time, heat is generated due to the loss due to the on-resistance of the analog switches SW1 to SWN and the dielectric loss of the piezoelectric elements C1 to CN, and the temperature of the head and ink rises.

  Next, driving waveforms for heating before printing by the droplet driving device according to the embodiment of the present invention will be described. FIG. 2 is a diagram illustrating an example of a driving waveform for heating before the printing operation of the droplet discharge device according to the embodiment of the present invention.

  As described above, the driving waveform shown in FIG. 1 is used during the printing operation, but the driving waveform shown in FIG. 2 is used when the head and ink are heated before the printing operation. In the drive waveform of FIG. 2, the fall time Tf ′ until the voltage waveform of the fine drive waveform reaches a predetermined voltage value is shorter than the fall time Tf of the fine drive waveform shown in FIG. It has become. Similarly, the rise time Tr ′ until the predetermined voltage value is reached is also shorter than the rise time Tr of the fine drive waveform used during the printing operation.

  Next, electrical characteristics at the time of heating the head before the printing operation and at the time of the printing operation of the droplet discharge device according to the embodiment of the present invention will be described. FIG. 4 shows (a) the voltage of the fine drive waveform, (b) the current of the fine drive waveform, and (b) the current of the fine drive waveform during the head heating before the printing operation and the printing operation of the droplet discharge device according to the embodiment of the present invention. (C) It is a figure explaining the power consumption of a fine drive waveform.

  In FIG. 4, in all of (a), (b), and (c), the rise time and the fall time of the fine drive waveform when the head is heated before the print operation are set to about 1 / of the fine drive waveform during the print operation. 2 is set. That is, as shown in FIG. 4A, the time until the fine drive waveform at the time of driving the head before the printing operation reaches a predetermined voltage value is about ½ compared with the fine drive waveform at the time of the printing operation. It's time for.

  Further, as shown in FIG. 4B, the current value that flows during charging and discharging of the piezoelectric element by the fine driving waveform at the time of driving the head before the printing operation is about twice the fine driving waveform at the time of the printing operation, and the flowing time is It is about 1/2 times. As shown in FIG. 4C, the power value consumed by the analog switch by the fine driving waveform at the time of driving the head before the printing operation is approximately equal to the fine driving waveform at the time of the printing operation when a current is flowing. The loss occurrence time is 4 times and is about 1/2 times.

  Since the temperature rise of the analog switch is substantially proportional to the average power consumption, the amount of heat generated by the fine driving by the driving waveform shown in FIG. 2 for heating before the printing operation is the same as that in the printing operation shown in FIG. This is about twice the amount of heat generated by the fine driving by the head driving waveform. Similarly, the dielectric loss of the piezoelectric element is approximately doubled.

  As described above, the rising time Tr ′ and the falling time Tf ′ until the voltage waveform of the fine driving waveform at the time of heating the head reaches a predetermined voltage value are shortened. As a result, it is possible to increase the amount of loss between the drive IC incorporating the analog switch and the piezoelectric element, and to raise the temperature in a short time.

  Next, the operation of the droplet discharge device according to the embodiment of the present invention will be described. FIG. 5 is a flowchart for explaining the operation of the droplet discharge device according to the embodiment of the present invention.

  In FIG. 5, the state of the droplet discharge device is detected in the process of step (hereinafter referred to as “S”) 501. In step S502, it is determined whether or not the state detected in step S501 is before the printing operation.

  If it is determined in the process of S502 that the print operation is not being performed (S502: Y), the process proceeds to S503. In the process of S503, a waveform Tr ′ having a short rise time and a waveform Tf ′ having a short fall time until the voltage waveform of the fine drive waveform at the time of head heating reaches a predetermined voltage value are applied. As a result, the current value flowing through the piezoelectric element and the driving IC becomes larger than the current value flowing during the printing operation, and the process ends.

  If it is determined in the process of S502 that it is not before the printing operation (S502: N), that is, printing is in progress, the process proceeds to S504. In the process of S504, a waveform Tr having a long rising time and a waveform Tf having a long falling time until the voltage waveform of the fine driving waveform during printing reaches a predetermined voltage value are applied. As a result, the current value flowing through the piezoelectric element and the driving IC becomes smaller than the current value flowing before the printing operation, and the process ends.

  As described above, in the embodiment of the present invention, when the head is heated, the analog switch connected to the head is turned on, and a drive waveform having a short rise time and short fall time is applied to the piezoelectric element. When a drive waveform is applied, current flows through the analog switch and the piezoelectric element during charging and discharging of the piezoelectric element. The temperature rises due to the loss of the on-resistance of the analog switch and the loss of the dielectric of the piezoelectric element that occur at this time.

  The temperature of the heated head and ink is detected by a temperature sensor (not shown), and the application of the fine drive waveform is stopped when the temperature detected by the temperature sensor reaches a predetermined specified value. May be. Further, when the temperature detected by the temperature sensor does not reach the specified value, the application operation of the fine drive waveform may be repeated. The specified value can be set to an arbitrary value that does not cause a change in print quality caused by a change in ink ejection characteristics due to a temperature change.

  The amount of loss proportional to the rising temperature is proportional to the square of the current and the time during which the loss occurs, and the flowing current is inversely proportional to the waveform fall time Tf and the rise time Tr. For example, when Tr is halved, the current Ir flowing in the Tr section is doubled, the loss amount Pr when the current is flowing is quadrupled, and the loss occurrence time is halved. The amount of loss generated during the Tr period is Pr × Tr = 2 times.

  By shortening the rise time Tr and the fall time Tf of the drive waveform as much as possible in the range where ink is not ejected, the loss amount and the rising temperature of the analog switch and the piezoelectric element can be increased, Heating can be performed efficiently.

  Accordingly, it is possible to provide a droplet discharge device that can shorten the waiting time from power-on to the start of printing.

  Note that each operation flow of the inspection method in the embodiment of the present invention shown in FIG. 5 can be executed by a program on a computer. That is, a CPU (not shown) built in the droplet discharge device loads a program stored in a storage medium composed of ROM, RAM, etc. (not shown), and the processing steps of the program are sequentially executed.

  In addition, the liquid ejection apparatus described above can be mounted on a recording apparatus such as an ink jet printer.

  As described above, according to the present invention, it is possible to obtain a droplet discharge device, a control method thereof, and a program that can shorten the waiting time from power-on to the start of printing.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

1 Flip-flop circuit 2 Latch circuit

JP 2005-153325 A

Claims (6)

A piezoelectric element that charges and discharges by applying a driving waveform;
A liquid ejection device including a driving unit that generates a fine driving waveform that does not cause ink to be ejected from a nozzle even when applied to the piezoelectric element,
A droplet discharge device, wherein a current value of a fine driving waveform before a printing operation is generated to be larger than a current value of a fine driving waveform during a printing operation.   The rise time and / or the fall time until the voltage waveform of the fine drive waveform before the printing operation reaches a predetermined voltage value is such that the voltage waveform of the fine drive waveform during the printing operation reaches the predetermined voltage value. 2. The droplet discharge device according to claim 1, wherein each of the droplet discharge devices is shorter than a rise time and / or a fall time.   When the fine driving waveform is applied, the power value consumed by the driving unit and the piezoelectric element before the printing operation is equal to the power consumed by the driving unit and the piezoelectric element during the printing operation. The droplet discharge device according to claim 1, wherein the droplet discharge device is larger than a value.   The temperature of the head and the ink that rises based on the power consumed by the driving means and the piezoelectric element before the printing operation, and the detection means for detecting the temperature of the head and the ink is set to a predetermined specified value. The droplet discharge device according to claim 3, further comprising means for determining whether or not it has been reached. A piezoelectric element that charges and discharges by applying a driving waveform;
And a driving unit that generates a fine driving waveform that does not cause ink to be ejected from a nozzle even when applied to the piezoelectric element,
A step of determining whether the determination unit is in a state before or during a printing operation;
When it is determined by the determining step that the state is before the printing operation, the driving unit compares the current value of the fine driving waveform with the current value of the fine driving waveform in the state during the printing operation. A process to generate
The control method characterized by including. A piezoelectric element that charges and discharges by applying a driving waveform;
A program that is executed by a computer of a droplet discharge device, including a drive unit that generates a fine drive waveform that does not discharge ink from a nozzle even when applied to the piezoelectric element,
A process of determining whether the determination unit is in a state before or during a printing operation;
If it is determined by the determination process that the state is before the printing operation, the driving unit compares the current value of the fine driving waveform with the current value of the fine driving waveform in the state during the printing operation. Process to generate
The program characterized by including.

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