Liquid droplet ejection apparatus

Abstract

A liquid droplet ejection apparatus includes a conveyor unit that conveys a recording medium, liquid droplet ejection head that records an image by ejecting liquid droplets onto the recording medium conveyed by the conveyor unit, and a controller that increases or decreases ejection timing of the liquid droplet ejection head in amounts equal to a correction time determined based on conveyance speed data of the conveyor unit such that a shift amount generated in a period from when the liquid droplet is ejected to when the liquid droplet lands on the recording medium becomes constant with respect to a reference position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a diagram showing the overall configuration of an inkjet recording apparatus pertaining to a first embodiment of the invention;

FIG. 2 is a diagram showing maintenance in the inkjet recording apparatus pertaining to the first embodiment of the invention;

FIG. 3 is a diagram showing the configuration of a conveyor belt and its vicinity pertaining to the first embodiment of the invention;

FIG. 4 is a diagram showing a modification where ejection timing-use marks pertaining to the first embodiment of the invention are disposed on a drive roll;

FIG. 5 is a diagram showing ejection timings of inkjet recording heads pertaining to the first embodiment of the invention;

FIG. 6 is a diagram showing a shift in the landing position of ink which arises in the inkjet recording apparatus pertaining to the first embodiment of the invention;

FIG. 7 is a diagram showing a data table of printing clocks and corrected printing clocks pertaining to the first embodiment of the invention;

FIG. 8 is a diagram showing the relationship between the printing clocks and the corrected printing clocks pertaining to the first embodiment of the invention;

FIG. 9 is a diagram showing a control mechanism in an inkjet recording apparatus pertaining to a second embodiment of the invention;

FIG. 10 is a diagram showing corrected printing clocks that are generated from printing clocks pertaining to the second embodiment of the invention;

FIG. 11 is a diagram showing corrected printing clocks generated from printing clocks pertaining to the second embodiment of the invention, and shows a case where the printing clocks are faster than a set value; and

FIG. 12 is a diagram showing an example where intervals between ejection timing-use marks pertaining to the second embodiment are spaced more roughly than the conveyance-direction resolution of the inkjet recording apparatus.

Claims

1. A liquid droplet ejection apparatus comprising: a conveyor unit that conveys a recording medium;a liquid droplet ejection head that records an image by ejecting liquid droplets onto the recording medium conveyed by the conveyor unit; anda controller that increases or decreases an ejection timing of the liquid droplet ejection head by a correction time determined based on conveyance speed data of the conveyor unit such that an amount of shift of the liquid droplets with respect to a reference position during a period from when the liquid droplets are ejected to when the liquid droplets land on the recording medium become constant.

2. The liquid droplet ejection apparatus of claim 1, wherein the correction time is determined in accordance with a preset conveyance speed of the conveyor unit, the conveyance speed of the conveyor unit actually measured, an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection head, and an ejection speed of the liquid droplets.

3. The liquid droplet ejection apparatus of claim 1, wherein the correction time is calculated, and the ejection timing of the ejection head is increased or decreased, by: ((the preset conveyance speed of the conveyor unit÷the conveyance speed of the conveyor unit actually measured)−1)×(an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection heads÷the ejection speed of the liquid droplets).

4. The liquid droplet ejection apparatus of claim 1, wherein the correction time of liquid droplet ejection is calculated from pre-measured conveyance speed data of the conveyer unit.

5. The liquid droplet ejection apparatus of claim 4, wherein the conveyor unit conveys the recording medium by the rotational force of a drive roll, andthe controller increases or decreases the ejection timings of the liquid droplet ejection head in a data table by the correction time calculated from conveyance speed profile data of the conveyor unit corresponding to one rotation of the drive roll, stores the data table in advance, and causes the liquid droplet ejection head to eject the liquid droplets on the basis of the data table.

6. The liquid droplet ejection apparatus of claim 3 further comprising a detection unit that detects marks added at substantially equidistant intervals to the conveyor unit wherein, the controller comprises: a calculation unit that acquires an ejection timing clock of the intervals between the passing of each mark detected by the detection unit,calculates the correction time from the acquired ejection timing clock, andoutputs the acquired ejection timing clock delayed an amount of time equal to the sum of the correction time plus one period of a reference clock that is a preset value of the ejection timing clock, anda timing controller that controls the ejection timings of the liquid droplet ejection head on the basis of the ejection timing clock output from the calculation unit.

7. The liquid droplet ejection apparatus of claim 1, wherein the controller adjusts the correction time in accordance with variations in an ejection distance between the recording surface of the recording medium and the ejection face of the liquid droplet ejection head that result from the type of the recording medium.

8. The liquid droplet ejection apparatus of claim 1, wherein the conveyor unit comprises an endless conveyor belt that is stretched around a drive roll and a driven roll.

9. A liquid droplet ejection apparatus comprising: a conveyor unit that conveys a recording medium;a liquid droplet ejection head that records an image by ejecting liquid droplets onto the recording medium conveyed by the conveyor unit; anda controller that, where the position of the recording medium facing the liquid droplet ejection head at the point in time when the liquid droplets are ejected from the liquid droplet ejection head serve as reference positions, increases or decreases ejection timings of the liquid droplet ejection head by amounts of a correction time duration determined based on conveyance speed data of the conveyor unit, making the distance between the reference positions and positions where the liquid droplets land on the recording medium become substantially constant.

10. The liquid droplet ejection apparatus of claim 9, wherein the correction time is determined in accordance with the preset conveyance speed of the conveyor unit, the conveyance speed of the conveyor unit actually measured, an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection head, and the ejection speed of the liquid droplets.

11. The liquid droplet ejection apparatus of claim 9, wherein the correction time is calculated, and the ejection timing of the ejection head is increased or decreased, by: ((the preset conveyance speed of the conveyor unit÷the conveyance speed of the conveyor unit actually measured−1))×(an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection heads÷the ejection speed of the liquid droplets).

12. The liquid droplet ejection apparatus of claim 10, wherein the conveyance speed actually measured is measured before the recording of the image by the liquid droplet ejection heads.

13. The liquid droplet ejection apparatus of claim 9, wherein the controller adjusts the correction time in accordance with variations in an ejection distance between the recording surface of the recording medium and the ejection face of the liquid droplet ejection head that result from the type of the recording medium.

14. The liquid droplet ejection apparatus of claim 9, wherein the conveyor unit conveys the recording medium by the rotational force of a drive roll, andthe controller retains conveyance speed profile data of the conveyor unit with respect to one rotation of the drive roll and a data table of the ejection timings of the liquid droplet ejection heads,calculates the correction time based on the conveyance speed profile data, andincreases or decreases values in the data table by the calculated correction time, stores a modified data table, and causes the liquid droplet ejection head to eject the liquid droplets on the basis of the modified data table.

15. The liquid droplet ejection apparatus of claim 14, wherein the correction times are calculated by: ((the preset conveyance speed of the conveyor unit÷the actual conveyance speed of the conveyance speed profile data)−1)×(an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection heads÷the ejection speed of the liquid droplets).

16. The liquid droplet ejection apparatus of claim 9, wherein the conveyor unit includes marks added at substantially equidistant intervals,the liquid droplet ejection apparatus further comprises a detection unit that detects the marks,the controller comprises a calculation unit and a timing controller and: holds in advance a reference clock of preset values of an ejection timing clock of liquid droplet ejection, andacquires a measured ejection timing clock of the intervals of time between the passing of each mark detected by the detection unit,the calculation unit calculates the correction time from the acquired measured ejection timing clock, and outputs the acquired ejection timing clock delayed by an amount of time equal to the sum of the correction time plus one period of the reference clock, andthe timing controller controls the ejection timing of the liquid droplet ejection head on the basis of the output ejection timing clock.

17. The liquid droplet ejection apparatus of claim 16, wherein the correction time is calculated by: ((the acquired measured ejection timing clock÷the reference clock)−1)×(an ejection distance from the recording surface of the recording medium to the ejection face of the liquid droplet ejection heads÷the ejection speed of the liquid droplets).