Inkjet recording device

Abstract

To heat a print head while suppressing an increase in time until recording starts.SOLUTION: An inkjet recording device has: a heating pulse thinning table setting a thinning pattern of heating pulse from thinning patterns of a plurality of heating pulses; and a heating pulse thinning table changeover part for switching heating pulse thinning tables in accordance with value counted by a speed difference overcounter. In a heating pulse generating part, the heating pulse thinning tables is switched in accordance with value counted by the speed difference overcounter, so that a thinning pattern of the heating pulse is switched according to a speed state of the motor.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus.

Background Art

[0002] An inkjet recording apparatus is configured to form an image by ejecting and flying ink droplets from ejection ports of a print head by thermal energy and attaching the droplets to a recording medium such as paper. Since the ejection amount changes when the temperature of the ink changes, a heating means is provided near the ink ejection port of the print head that ejects the ink, and a device is known that controls the ink temperature to be a certain level or higher when starting printing.

[0003] At this time, if control is performed to simultaneously drive the carriage motor, the conveyance motor, and the heating of the print head, a large amount of power is consumed when accelerating the heating of the print head and the motor drive. Therefore, the power consumption instantaneously increases. For this reason, a larger power supply capacity is required according to the peak of the power consumption, and the cost also increases accordingly.

[0004] Patent Document 1 discloses that it includes a print head heating means and drive control means for controlling each drive so that the print head heating means, the carriage motor, and the conveyance motor are not all driven simultaneously.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the inkjet recording apparatus of Patent Document 1, since the heating of the print head, the driving of the carriage motor, and the driving of the conveyance motor are completely exclusive and controlled, it takes time until the start of recording.

[0007] The present invention has been made in view of the above problems, and an object thereof is to heat the print head while suppressing an increase in the time until the start of recording.

Means for Solving the Problems

[0008] The present invention includes a printing head that discharges ink, heating control means for controlling heating of the printing head, a carriage motor that scans the printing head, carriage motor control means for controlling the carriage motor, a conveyance motor that conveys a recording medium, conveyance motor control means for controlling the conveyance motor, and heating pulse control means for controlling heating pulses for heating the printing head. The carriage motor control means includes a speed detection unit, a speed difference detection unit that detects a speed difference from the speed detection unit, a speed difference history register that holds a history of the speed difference detected by the speed difference detection unit, a speed difference threshold setting unit that can arbitrarily set a threshold of the speed difference for determining the degree of acceleration, a speed difference overcounter that compares values of the speed difference history register and the speed difference threshold setting unit and counts the number of times the held speed difference history register becomes larger than the value of the speed difference threshold setting unit, and a heating pulse mask signal generation unit that controls a mask of heating pulses according to the count value of the speed difference overcounter. The heating pulse control means includes a heating pulse generation unit that generates a heating pulse signal, heating pulse thinning means for thinning out the output of the heating pulse generated by the heating pulse generation unit, a heating pulse thinning table for setting a thinning pattern of the heating pulse from among thinning patterns of a plurality of heating pulses, and a heating pulse thinning table switching unit that switches the heating pulse thinning table according to the value counted by the speed difference overcounter. In the heating pulse generation unit, by switching the heating pulse thinning table according to the value counted by the speed difference overcounter, the thinning pattern of the heating pulse is switched according to the speed state of the motor, which is characterized thereby.

Effect of the Invention

[0009] According to the present invention, it is possible to heat the printing head while suppressing an increase in the time until the start of recording.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the members, numerical values, materials, etc. used in the description are merely examples for facilitating understanding and are not intended to limit the present invention.

[0012] (First Embodiment) In the first embodiment, a case where the present invention is applied to a carriage motor control block for driving a carriage of an inkjet printer will be exemplified. Note that the present invention is not limited to the carriage motor control of a printer and can also be applied to a motor control block for driving other motors mounted in a printer.

[0013] FIG. 1 is an external perspective view showing the configuration of an inkjet recording apparatus equipped with an inkjet print head (hereinafter referred to as a print head) that discharges ink droplets according to the inkjet method of the present embodiment.

[0014] The carriage 3 equipped with the printing head 2 is slidably supported by the guide shaft 4 and reciprocates on the recording medium (sheet) 1. At one end of the moving range of the carriage 3, a carriage motor (DC motor) 5 with a pulley is arranged, and an idle pulley 6 is arranged at the other end. A timing belt 7 is wound around these, and the carriage 3 and the timing belt 7 are connected.

[0015] Also, in order to prevent the carriage 3 from rotating around the guide shaft 4, a support member 8 extending parallel to the guide shaft 4 is installed, and the carriage 3 is also slidably supported by the support member 8. Further, a large number of recording elements are provided on the printing head 2, and an FFC (Flexible Flat Cable) 11 for supplying a drive signal of the recording element from the main body of the inkjet recording apparatus to the printing head 2 is arranged. The FFC 11 has an elongated and thin film shape, and a conductor pattern for transmitting a drive signal is formed inside or on the surface thereof, and it bends as the carriage 3 moves, and has flexibility such that the center position of the bending moves.

[0016] Furthermore, an ink tank (not shown) is arranged outside the carriage 3, and a tube 12 for supplying the ink stored in the ink tank to the printing head 2 is arranged. The tube 12 bends as the carriage 3 moves, and has flexibility such that the center position of the bending moves. The connecting member 10 composed of these FFC 11 and the tube 12 is connected between the carriage 3 and the fixed portion 9 of the inkjet recording apparatus main body.

[0017] In addition, the linear scale 16 used to obtain the position information of the carriage 3 is arranged in parallel along the carriage movement direction (main scanning direction) and is configured to be read by the encoder sensor 15 attached to the carriage 3. Further, ink recovery ports 14a and 14b for recovering the ink preliminarily discharged by the print head 2 are provided on both outer sides in the width direction of the recording medium 1. This preliminary discharge is an operation for discharging the ink adhering to the nozzle tip portion immediately before the start of recording or during the execution of recording at a position unrelated to recording.

[0018] With such a configuration, the carriage 3 reciprocates in the direction of arrow A (main scanning direction). Also, the recording medium 1 is conveyed in the direction of arrow B (sub-scanning direction) perpendicular to the carriage 3 by a conveyance motor (not shown).

[0019] Figure 2 shows the hardware configuration for operating the inkjet recording apparatus of Figure 1, and includes a control unit 17 that performs image processing and various actuator controls, and includes a CPU 21. The CPU 21 is an arithmetic processing unit that performs various control arithmetic processes while expanding the program stored in the ROM 23 into the RAM 22. The operation panel 18 is used for various settings of the printer, and for example, issues an instruction to start copy printing. The ASIC 19 is an arithmetic processing unit composed of an integrated circuit for performing image processing and actuator operations, and executes arithmetic processing in response to instructions from the CPU 21. The CPU 21 also executes the arithmetic processing for driving control of the carriage function in the case of this proposal. Note that the CPU 21 may be configured to be included in the ASIC 19 or mounted on a separate chip, and either configuration is acceptable. The communication unit 20 is used when issuing a print command including image data from the PC 24, and the printer side starts the printing operation when it receives the image data at the communication unit 20.

[0020] FIG. 3 is a block diagram showing an example of a hardware configuration for implementing carriage driving. To control the driving of the carriage, an encoder sensor signal output from a carriage motor encoder sensor 15 mounted on the carriage is input to a carriage motor control block 26 in the ASIC 19 and used for carriage motor drive control. There is also a print head control block 27 that generates necessary control and data for the print head 2, and here, heating control necessary for ink ejection by an inkjet method is also performed. The heating control includes not only preheating to a predetermined temperature before starting printing but also control to perform heating at a constant cycle to maintain a predetermined temperature, and the control is performed by inputting a heating pulse signal. The heating pulse signal is generated for each nozzle row of the print head. The heating pulse signal is generated by a heating pulse generation block 28 in the ASIC 19 so as to perform heating control according to the state of motor control based on the speed and position information output from the carriage motor control block 26. As an example of other motors, a conveyance motor encoder sensor 30 for controlling the driving of a conveyance motor 29 and a conveyance motor control block 31 in the ASIC 19 are shown, and it is assumed that the conveyance motor control block 31 functions in the same manner as the carriage motor control block 26.

[0021] FIG. 4 shows a conventional configuration and represents a state in which output and stop of heating pulses are performed according to a speed difference. When a specified speed difference is detected, a heating pulse mask signal for stopping the output of heating pulses is made valid, and the output of heating pulses is stopped while the heating pulse mask signal is valid, and the output of heating pulses is resumed when the heating pulse mask signal becomes invalid. While the output of heating pulses is stopped, a heating pulse off period counter counts up, and after the output of heating pulses is resumed, the number of pulses obtained by adding the heating pulses counted by the heating pulse off period counter to the originally set number of heating pulses is output in total. However, in the configuration of FIG. 4, there is a concern that the period during which heating pulses are not output becomes too long and the temperature necessary for ink ejection of the print head cannot be maintained.

[0022] To solve this problem, a configuration as shown in FIG. 5 was also considered. FIG. 5 shows a state in which thinning of the heating pulse is performed in addition to the conventional configuration of FIG. 4. In the configuration of FIG. 4, the output of the heating pulse was stopped while the heating pulse mask was effective. However, in the configuration of FIG. 5, since it is possible to output the thinned heating pulse according to the specified thinning period, it is possible to prevent the period during which the heating pulse is not output from becoming too long and the temperature required for ink ejection of the print head from not being maintained. Furthermore, since the generation period of the heating pulse is the same as that in the conventional configuration where the mask of the heating pulse is not executed, it is a configuration that does not affect the throughput.

[0023] However, in the conventional configuration, although thinning of the heating pulse could be performed, there was a problem that the temperature adjustment for the print head unit could not be finely controlled because it could only be controlled with a fixed thinning amount.

[0024] Hereinafter, a configuration for solving the problems in such conventional control will be described.

[0025] FIG. 6 is a diagram showing the interiors of the carriage motor control block 26 and the heating pulse generation block 28 described with reference to FIG. 3 in the first embodiment. The carriage motor control block 26 receives an encoder signal from the carriage motor encoder sensor 15 in the same manner as the conventional configuration, and the speed detection unit 40 acquires the speed, and similarly the position detection unit 45 acquires the position. The speed and position information thus obtained is used for driving control of the carriage motor, but the details are not described here because it is general firmware control that performs calculations using a CPU. Note that, although the motor control block is described by taking the carriage motor control as an example, other motor control blocks may be applied as long as they are not limited to the carriage motor control. Next, in order to see the change state of the speed from the speed information acquired by the speed detection unit 40, the speed difference calculation unit 41 calculates the speed difference and holds (stores) it in the speed difference history register 60. Next, the speed difference stored in the speed difference history register 60 is compared with an arbitrary threshold value set in the speed difference threshold value setting unit 42, and the number of speed difference histories exceeding the threshold value is counted by the speed difference over counter 61. By doing so, it can be determined that the greater the count value of the speed difference over counter 61, the greater the degree of motor acceleration, and the smaller the count value, the smaller the degree of acceleration. Note that, since the determination accuracy of the degree of motor acceleration varies depending on the number of histories that can be stored in the speed difference history register 60, the appropriate number of speed difference histories to be stored is appropriately set according to the product configuration and the like. The count value of the speed difference over counter 61 is output to the heating pulse mask signal generation unit 43 and the heating pulse generation block 28. The heating pulse mask signal generation unit 43 can control the mask signal either by the value from the speed difference over counter 61 or at an arbitrary timing. When the heating pulse mask signal is controlled by the speed difference over counter 61, the heating pulse mask signal for masking the heating pulse becomes valid when the count value of the speed difference over counter 61 is other than 0, and becomes invalid when the count value is 0, and is output to the heating pulse generation block 28.

[0026] Within the heating pulse generation block 28, a heating pulse is generated by the heating pulse generation unit 51 using the position information and speed information output from the carriage motor control block 26 and the information from the heating pulse control setting unit 50. The heating pulse generated at this time is the one before thinning. The thinning setting of the heating pulse is configured to hold a plurality of table data in the heating pulse thinning table 53, and the table can be switched by the heating pulse thinning table switching unit 54. Here, it is assumed that the content and number of the heating pulse thinning table can be variable depending on the product configuration and the like. The heating pulse thinning table switching unit 54 performs table switching setting based on the count value output from the speed difference over counter 61, and the selected thinning table is output to the heating pulse thinning unit 52. In the heating pulse thinning unit 52, thinning is performed according to the selected thinning table when the heating pulse mask signal is valid, and when the heating pulse mask signal is invalid, the heating pulse is output to the print head control block 27 without performing thinning. Note that in FIG. 6, the configuration is such that the thinning process of the heating pulse is executed inside the heating pulse generation block 28, but the thinning process may be executed on the motor control block side, or it may be newly configured as another functional block. Also, although the heating pulse thinning table switching unit 54 is configured to switch the thinning table based on the speed difference information, it is also possible to configure it to be switched by other controls such as position information and time information.

[0027] FIG. 7 shows the motor speed state when the motor is controlled with the proposed configuration, and the state where the generation of the heating pulse and its thinning setting are switched. Here, a configuration with four speed difference history registers is adopted, and an example is shown in which a heating pulse in a state where thinning control is not performed is output from the position of Pos_c to the position of Pos_k using the position information in the motor control block.

[0028] When there are four speed difference history registers numbered from 0 to 3, speed difference information is stored in the order from the 0th in the order of the encoder edge timing. Therefore, the newest speed difference information is stored in the speed difference history register 0, and the oldest speed difference information is stored in the speed difference history register 3. The speed difference history obtained in this way is compared with the threshold value set in the speed difference threshold setting unit 42, and when it becomes larger than the threshold value, it is determined that there is acceleration. The number of histories determined to have acceleration is counted by the speed difference over counter 61. The thinning table of the heating pulse is switched according to the count value of the speed difference over counter 61. Therefore, in FIG. 7, since the count value is 4 at the position of Pos_c, Table 4 is selected as the thinning table, and since the count value is 3 at the next position Pos_d, Table 3 is selected as the thinning table. Also, when the count value is 0 as in the case of the positions of Pos_i and Pos_k, no table is selected and no thinning is performed. In FIG. 7, although the state where the heating pulse mask signal is switched between valid and invalid according to the value of the speed difference over counter is illustrated, it can also be switched by other controls such as position information and time information.

[0029] As described above, by determining the degree of acceleration of the motor from the speed difference history information and realizing the thinning of the heating pulse according to the speed state of the motor, the accuracy of the temperature adjustment for the print head can be improved.

[0030] (Second Embodiment) In the first embodiment, the configuration when there is one motor for observing the speed state is shown. However, the configuration when observing the states of a plurality of motors and reflecting it in the thinning of the heating pulse is shown in FIG. 8 as the second embodiment.

[0031] In this embodiment, in addition to the configuration of the first embodiment, similar to the carriage motor control block 26, the conveyance motor control block 31 also has a speed detection unit 70, a speed difference calculation unit 71, a speed difference threshold setting unit 72, a speed difference history register 73, a speed difference overcounter 74, and a heating pulse mask signal generation unit 75. The count value of the speed difference overcounter 74 and the heating pulse mask signal generated by the heating pulse mask signal generation unit 75 are output to the heating pulse generation block 28. In the heating pulse thinning table switching unit 54 in the heating pulse generation block 28, the thinning table 53 is switched based on two parameters: the count value of the speed difference overcounter from the carriage motor control block 26 and the count value of the speed difference overcounter from the conveyance motor control block 31. Further, in the heating pulse thinning unit 52, the table data of the heating pulse thinning table 53, the heating pulse mask signal from the carriage motor control block 26, and the heating pulse mask signal from the conveyance motor control block 31 are input, and heating pulse thinning is performed based on the degree of acceleration of both carriage motor control and conveyance motor control. Although two motor control blocks are illustrated in FIG. 8, it is assumed that information on even more motor control blocks may be input to the heating pulse generation block.

[0032] In this way, a configuration is provided that can reflect the states of multiple motor controls in the thinning of heating pulses.

[0033] (Third Embodiment) In the above-described embodiment, the thinning of heating pulses was controlled based on the speed difference information detected by the motor control block. However, a configuration can also be proposed in which heating pulse thinning can be performed even when the speed itself increases. In the heating pulse thinning table switching unit, the heating pulse thinning table is switched according to two parameters: the speed detected by the speed detection unit and the speed difference detected by the speed difference detection unit. By doing so, in addition to the state where the degree of motor acceleration increases, a configuration is provided that can also reflect the state where the speed of the motor itself increases in the thinning of heating pulses.

[0034] (Fourth Embodiment) In the above-described embodiment, a DC motor was used as an example of the motor controlled by the motor control block, but the same configuration can be adopted for a stepping motor. In the case of a DC motor, motor control was performed using an encoder signal. However, since a stepping motor is controlled by a pulse signal, the number of pulse signals can be treated as position information, and the period of the pulse signal can be treated as speed information. Therefore, by using the pulse signal of the stepping motor instead of the encoder signal shown in FIGS. 6, 7, and 8, it is possible to perform thinning of heating pulses reflecting the speed state of the motor in the same manner as in the above-described embodiment.

Explanation of Signs

[0035] 2 Printing head 3 Carriage 5 Carriage motor 19 ASIC 20 Communication unit 21 CPU 22 RAM 23 ROM 24 PC

Claims

1. A printing head that ejects ink, Heating control means for controlling heating of the printing head, A carriage motor that scans the printing head, Carriage motor control means for controlling the carriage motor, A conveyance motor for conveying a recording medium, Conveyance motor control means for controlling the conveyance motor, Heating pulse control means for controlling heating pulses for heating the printing head, having, The carriage motor control means, a speed detection unit, a speed difference detection unit that detects a speed difference from the speed detection unit, a speed difference history register that holds a history of the speed difference detected by the speed difference detection unit, a speed difference threshold setting unit that can arbitrarily set a threshold value of the speed difference for determining the degree of acceleration, a speed difference overcounter that compares the values of the speed difference history register and the speed difference threshold setting unit and counts the number of times the held speed difference history register becomes larger than the value of the speed difference threshold setting unit, a heating pulse mask signal generation unit that controls the mask of heating pulses according to the count value of the speed difference overcounter, The heating pulse control means, a heating pulse generation unit that generates a heating pulse signal, heating pulse thinning means for thinning the output of the heating pulse generated by the heating pulse generation unit, a heating pulse thinning table for setting a thinning pattern of the heating pulse from among thinning patterns of a plurality of heating pulses, a heating pulse thinning table switching unit that switches the heating pulse thinning table according to the value counted by the speed difference overcounter, An inkjet recording apparatus, characterized in that, in the heating pulse generation unit, the thinning pattern of the heating pulse is switched according to the speed state of the motor by switching the heating pulse thinning table according to the value counted by the speed difference overcounter.

2. The inkjet recording apparatus according to claim 1, wherein the heating pulse thinning table switching unit switches the heating pulse thinning table according to the arrangement and number of nozzles of the printing head.

3. The inkjet recording apparatus according to claim 1, wherein the heating pulse thinning table switching unit switches the heating pulse thinning table according to two parameters, namely, the speed detected by the speed detection unit and the speed difference detected by the speed difference detection unit.

4. The motor control means in the inkjet recording apparatus has a position detection unit that detects position information necessary for motor control, and the heating pulse skip table switching unit switches the heating pulse skip table according to the position detected by the position detection unit. The inkjet recording apparatus according to claim 1, characterized in that.

5. The heating pulse skipping unit and the heating pulse skip table switching unit switch the heating pulse skip table according to the speed states of a plurality of motors by acquiring speed information from a plurality of motor control means. The inkjet recording apparatus according to claim 1, characterized in that.

Images