JP2010120301A - Inkjet recorder and method of driving inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder that can exactly confirm which nozzle is in a non-ejection state when detecting non-ejection of a nozzle. <P>SOLUTION: This inkjet recorder includes an inkjet recording head for ejecting ink by using thermal energy generated by a thermal energy conversion unit, a timing control means for controlling a timing for applying an ejection pulse, and a plurality of temperature detection means that respectively detect temperature at portions each being in the vicinity of each of a plurality of ink ejection nozzles formed in the inkjet recording head, the temperature detection means being independent from each other and serially connected to each other. The inkjet recorder further includes a signal selection means that selects at least one from the serially connected plurality of temperature detection means and selects a temperature detection value corresponding to the selected temperature detection means so as to output the temperature detection value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet recording apparatus and a method for controlling the apparatus, and more particularly to an inkjet recording apparatus that ejects ink using thermal energy generated from a thermal energy converter.

  An ink jet recording apparatus of a type in which a plurality of recording heads each including a plurality of recording elements are fixed in parallel and a recording medium is scanned and recorded is commercially available. An ink jet recording apparatus having this type of configuration is characterized in that the recording speed is faster than a so-called serial scan method in which recording is performed by scanning a recording head.

  In this type of ink jet recording apparatus, in order to obtain a good image, in order to minimize the occurrence of density fluctuations and density unevenness in the recorded image or the like, in particular, control for stabilizing the ejection amount ejected from the recording head is performed. Various things are done.

  If the temperature of the ink is high, the viscosity of the ink becomes low, the ink is easily ejected, and the ejection amount increases. By adjusting the ink temperature (hereinafter also referred to as “temperature control”), the ejection amount, etc. Control the ink viscosity that affects the ink.

  In addition, in the method of providing a heating element, generating bubbles in the ink by the heat energy generated by the heating element, and discharging the ink by the growth of the bubbles, the bubble generation conditions are controlled, and the discharge amount and the like are controlled. It is known to stabilize (see, for example, Patent Document 1).

  As a specific example of adjusting the ink temperature, a heater for heating the recording head holding the ink and a temperature sensor for detecting the temperature related to the recording head are provided, and the temperature detected by the temperature sensor is used as a heating amount by the heater. This is an example of feedback.

  In this configuration, it is necessary to accurately measure steep temperature changes in the vicinity of the nozzles, particularly in the vicinity of the nozzles, and a temperature sensor is arranged in the vicinity of the nozzles, and more than one are arranged to measure the temperature distribution generated in the nozzle row direction. There are many cases to do.

  In addition, there are cases where a means for detecting non-ejection of ink droplets due to ink clogging or the like is mounted, and there are various methods for this non-ejection detection. One of them is a method of detecting by detecting a temperature change near the nozzle. Has been proposed (see, for example, Patent Document 2). In this method, non-ejection can be detected by determining the difference in temperature change between normal ejection and non-ejection.

In order to detect non-ejection of ink droplets due to ink clogging, etc., the temperature change in the vicinity of the nozzle during normal ejection is measured in advance, and the temperature change in the vicinity of the nozzle is periodically measured, resulting in a difference in temperature change. In this case, it can be determined that there is no ejection.
JP-A-5-31905 JP-A-11-198375

  As described above, the temperature distribution data necessary for detecting the non-ejection of ink droplets and controlling the ink ejection amount is obtained by arranging the temperature sensors in the vicinity of the ejection nozzles on a one-to-one basis for each nozzle. be able to.

  FIG. 7 is a diagram showing a conventional ink jet recording apparatus PR2 composed of four nozzles.

  The temperature sensors 101 to 104 are temperature detection elements configured by resistors or diodes. A 2-bit selection signal 109 is input to the analog switches 106 and 107 so that a current flows from the constant current source 105 to any one of the temperature sensors 101 to 104.

  Here, when the analog switch 106 selects the circuit 1 and the analog switch 107 selects the circuit A, a constant current is supplied to the temperature sensor 101. Since the voltage at both ends of the temperature sensor 101 is a voltage value proportional to the temperature change, this voltage is amplified by the operational amplifier 108 and then input to a control circuit (not shown) to be processed as temperature data.

  By sequentially changing the value of the 2-bit selection signal 109, the voltage values of the temperature sensors 101 to 104 can be read sequentially.

  Here, the reading timing of the voltage value output from the temperature sensors 101 to 104 differs depending on whether it is used for non-ejection detection or ink ejection amount control. When used for non-ejection detection, it may be performed during a series of ejections after being heated by an ejection control unit (not shown), or immediately after the ink droplets immediately after the heating are ejected from the nozzles. It is common. On the other hand, when used for ink ejection volume control, the heat of the heater at the time of ink ejection diffuses to the periphery, and after a certain amount of time has passed since the ink ejection when the nozzle periphery became almost uniform, Generally, this is performed immediately before heating of the heater.

  In this conventional example, since there are several nozzles, it does not take a long time to sequentially measure the outputs of all the temperature sensors. Time is required. In non-ejection detection, for example, a method of performing non-ejection detection processing between pages being printed, for example, can be considered. However, when the total number is measured in order to acquire the ink discharge amount control data, there is a problem that accurate feedback cannot be performed and the response speed is lowered due to time restrictions.

  Further, in order to obtain the ink discharge amount control data, it is conceivable to measure a small number of temperature sensors without performing the total measurement, but this method cannot accurately read the temperature distribution in the nozzle array direction. There's a problem.

  An object of the present invention is to provide an ink jet recording apparatus and a method of driving the ink jet recording apparatus, which can confirm in detail which nozzle is not ejecting when performing nozzle non-ejection detection.

  The present invention comprises a thermal energy converter, an inkjet recording head that ejects ink using thermal energy generated from the thermal energy converter, and timing control means for controlling the timing of applying ejection pulses; A plurality of independent temperature detecting means for individually detecting temperatures in the vicinity of each of the plurality of ink discharge nozzles formed inside the ink jet recording head, wherein the plurality of temperature detecting means are connected in series with each other. And at least one temperature detection means among the plurality of temperature detection means connected in series to each other, and a signal selection means for selecting and outputting a temperature detection value corresponding to the selected temperature detection means; Inkjet recording apparatus having

  According to the present invention, when nozzle ejection failure detection is performed, the values of the temperature sensors are individually read, so that it is possible to confirm in detail which nozzle is ejection failure.

  Further, according to the present invention, when the head temperature is detected for controlling the ink discharge amount, the added value of the output signals of the plurality of temperature sensors can be read, so that the temperature distribution in the nozzle row direction can be grasped in a short time. There is an effect that can be.

  Furthermore, according to the present invention, there is an effect that two types of temperature information can be acquired without increasing the number of analog switches constituting the circuit.

  The best mode for carrying out the invention is the following embodiment.

  In the embodiments described below, a printer will be described as an example of a recording apparatus using an inkjet recording method.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to forming significant information such as characters and graphics. In other words, “recording” forms images, patterns, patterns, etc. on a wide range of recording media, regardless of whether they are significant involuntary, or whether they are manifested so that humans can perceive them with a sense. It also represents the case where the medium is processed.

  The “recording medium” represents not only paper used in general recording apparatuses but also a wide variety of materials capable of receiving ink, such as cloth, plastic, metal plate, glass, ceramics, wood, and leather.

  Furthermore, “ink” (sometimes referred to as “liquid”) should be widely interpreted, as is the definition of “recording (printing)”. That is, the “ink” is applied onto the recording medium, thereby forming an image, a pattern, a pattern or the like, processing the recording medium, or processing the ink (for example, coagulation of the colorant in the ink applied to the recording medium). Or a liquid that can be subjected to insolubilization.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an ink jet recording apparatus PR1 that is Embodiment 1 of the present invention.

  The inkjet recording head 30 includes four recording heads 31 to 34 that eject inks of black (K), cyan (C), magenta (M), and yellow (Y). These recording heads 31 to 34 are driven by a control unit, which will be described later, and eject ink droplets of the corresponding ink to perform color recording.

  A sheet-like recording medium (hereinafter, referred to as “recording paper”) ST is fed from a feeding unit (not shown), and passes under the inkjet recording head 30 while being electrostatically attracted to the transport belt 2 and moving. When recording is done. The conveyance belt 2 as a conveyance device is an annular belt member, and is stretched by the conveyance belt drive roller 5 and the support rollers 6 and 7, and conveys the recording paper ST by being driven to rotate.

  The belt cleaning unit 8 removes ink adhering to the belt.

  FIG. 2 is a block diagram showing a control configuration of the ink jet recording apparatus PR1.

  In FIG. 2, the same elements as those shown in FIG. 1 are denoted by the same reference numerals. That is, the inkjet recording apparatus PR1 is provided with a black recording head 31, a cyan recording head 32, a magenta recording head 33, a yellow recording head 34, and a conveyance belt drive roller 5. The recording heads 31 to 34 are configured with temperature sensor units 311 to 314 that detect the temperature of the head, and each temperature sensor is disposed in the vicinity of the ejection nozzle. The connection of the temperature sensor will be described in detail separately.

  The control unit 20 includes a CPU 21, a ROM 22 that stores programs, a RAM 23 that stores work data necessary for control, and a gate array 24. The gate array 24 outputs a drive control signal for the conveying belt drive roller 5, an image signal and a control signal for the ink jet recording head 30, a drive control signal for the cleaning unit 8, and the like. The image memory 25 stores an image, and the gate array 24 temporarily stores recording data received from the outside.

  FIG. 3 is a view showing a structure around the ink discharge port of the ink jet recording head in the ink jet recording apparatus PR1.

  3 (1) is a front view around the ink discharge port of the ink jet recording head, FIG. 3 (2) is a side view around the ink discharge port of the ink jet recording head, and FIG. FIG. 6 is a rear view around the ink discharge port of the recording head. FIG. 3 (4) is a perspective view showing the entire periphery of the ink discharge port of the ink jet recording head.

  As shown in FIG. 3B, the recording heads 31 to 34 have a plurality of head chips 43 attached to the base plate 40.

  As illustrated in FIG. 3B, the head chip 43 is bonded and fixed to the base plate 40 so that the ink supply path 41 formed in the base plate 40 and the ink supply port 44 are aligned. In the head chip 43, two nozzle rows 45 and 46 are formed on the surface opposite to the ink supply side.

  The nozzle rows 45 and 46 share the ink supply port 44 and are supplied with ink through the ink supply path 41. The nozzle rows 45 are provided at a pitch of 600 dpi, and the nozzle rows 46 are provided at the same pitch as the nozzle rows 45 so as to complement the nozzles of the nozzle rows 45, and printing at 1200 dpi is possible with two rows.

  The ink supplied to the nozzle arrays 45 and 46 generates bubbles due to a phase change due to a print pulse signal applied to the heater of each nozzle, and ink droplets are pushed out from the ejection openings. At this time, the ink droplet takes heat from the heater inside the nozzle and takes it out of the head. The difference between ink ejection and non-ejection is mainly the presence or absence of heat brought out by the ejected ink. The temperature sensors 49 and 50 provided in the vicinity of the nozzle arrays 45 and 46 use the above difference as a temperature difference. It can be detected from the outside.

  FIG. 4 is a diagram showing an ink jet recording apparatus PR1 composed of four nozzles, and is a diagram showing an external output circuit for temperature sensor signals and a signal selection means 70.

  The signal selection means 70 is composed of an analog switch SW1 and an analog switch SW2. The temperature sensors 51 to 54 are temperature detection elements configured as resistors.

  First, a method for individually measuring each temperature sensor value will be described.

  When the measurement is performed by any one of the temperature sensors 51 to 54, a 2-bit selection signal SS1 is supplied to each of the analog switches SW1 and SW2 so that the current from the constant current source 55 flows to any one of the temperature sensors. A 2-bit selection signal SS2 is input.

  When the temperature sensor 51 measures the temperature, a constant current is supplied to the temperature sensor 51 by selecting the circuit 1 of the analog switch SW1 and the circuit A of the analog switch SW2. That is, the first selection signal SS1 selects the circuit 1 of the analog switch SW1, and the second selection signal SS2 selects the circuit A of the analog switch SW2, thereby causing a constant current to flow through the temperature sensor 51. Since the voltage across the temperature sensor 51 is a voltage value proportional to the temperature change, the voltage across the temperature sensor 51 is amplified by the operational amplifier 60, and then converted into digital data by the A / D converter 61. Input to the control circuit and processed as temperature data.

  Similarly, when the temperature sensor 52 measures the temperature, the first selection signal SS1 selects the circuit 2 of the analog switch SW1, and the second selection signal SS2 selects the circuit B of the analog switch SW2. A constant current is passed through the temperature sensor 52. When the temperature sensor 53 measures the temperature, the first selection signal SS1 selects the circuit 3 of the analog switch SW1, and the second selection signal SS2 selects the circuit C of the analog switch SW2. Shed. When the temperature sensor 54 measures the temperature, the first selection signal SS1 selects the circuit 4 of the analog switch SW1, and the second selection signal SS2 selects the circuit D of the analog switch SW2, thereby determining the temperature sensor 54. Apply current.

  Next, a method for collectively measuring the temperature measurement values by a plurality of temperature sensors will be described.

  In order to measure the sum of the output signal of the temperature sensor 51 and the output signal of the temperature sensor 52, the first selection signal SS1 selects the circuit 1 of the analog switch SW1, and the second selection signal SS2 is the analog switch SW2. Circuit B is selected. Accordingly, a constant current is passed through the temperature sensors 51 and 52, and an added value of the output signal of the temperature sensor 51 and the output signal of the temperature sensor 52 is generated at the measurement point P1 and can be read.

  To measure the added value of the output signal of the temperature sensor 53 and the output signal of the temperature sensor 54, the first selection signal SS1 selects the circuit 3 of the analog switch SW1, and the second selection signal SS2 is the analog switch SW2. Circuit D is selected. Accordingly, a constant current is passed through the temperature sensors 53 and 54, and an added value of the output signal of the temperature sensor 53 and the output signal of the temperature sensor 54 is generated at the measurement point P1 and can be read.

  As described above, by selecting from the outside (by receiving the selection signals SS1 and SS2), an arbitrarily designated number of addition values of the plurality of temperature sensors 51 to 54 arranged in a row are acquired in a single measurement. Can do. When the first selection signal SS1 selects the circuit 1 and the second selection signal SS2 selects the circuit C, the added value of the output signals of the three temperature sensors 51, 52, 53 can be read at the measurement point P1. it can.

  When the first selection signal SS1 selects the circuit 1 and the second selection signal SS2 selects the circuit D, the added value of the output signals of the four temperature sensors 51, 52, 53, 54 is read at the measurement point P1. be able to.

  Based on the voltage value corresponding to the temperature input to the control circuit (not shown), the average value of the specified number of nozzle temperatures provided in the vicinity of the temperature sensor can be calculated in a short time.

  In the above description, the number of nozzles that eject ink is four, but the number of nozzles may be increased to five or more. Further, these circuits may be used as one unit, and a plurality of units may be used.

  In addition, the analog switches SW1 and SW2, the operational amplifier 60, the A / D converter 61, and the constant current source 55 are preferably provided at positions close to the ink jet recording head in order to reduce the influence of noise. Further, when a semiconductor is used as the head chip 43, these circuits can be configured inside the head chip 43.

  The inkjet recording head 30 is an example of an inkjet recording head that includes a thermal energy converter and ejects ink using thermal energy generated from the thermal energy converter.

  The control unit 20 is an example of a timing control unit that controls the timing of applying the ejection pulse.

  The temperature sensors 51 to 54 are a plurality of independent temperature detecting means for individually detecting temperatures in the vicinity of each of the plurality of ink ejection nozzles formed inside the ink jet recording head, and are connected in series to each other. This is an example of a plurality of temperature detecting means.

  The signal selection means 70 selects at least one temperature detection means from among the plurality of temperature detection means connected in series to each other, and selects and outputs a temperature detection value corresponding to the selected temperature detection means. It is an example of a signal selection means.

  In this case, the temperature detecting means is driven by a constant current source input from the outside of the ink jet recording head, and is a means for outputting the voltage across the element incorporated in the temperature detecting means as a temperature detection value. is there. The element built in the temperature detecting means is a resistor. Further, the signal selection means 70 selects a temperature detection value corresponding to the temperature detection means selected according to the first selection signal and the second selection signal input from the outside of the ink jet recording head. It is a means to output. The temperature detection value output in response to the first selection signal is a value used for non-ejection detection of each nozzle. In addition, the temperature detection value output in response to the second selection signal is a value used as a control value for the discharge amount control for controlling the discharge amount of the ink jet recording head. The recording head is a recording head that ejects ink using thermal energy, and has a thermal energy converter for generating thermal energy applied to the ink.

  FIG. 5 is a diagram showing the temperature distribution of the chip on the ink jet recording head.

  If the ink is ejected uniformly from the nozzle rows, the central portion is the highest and the temperatures at both ends are low, as shown in the temperature distribution curve C1. If the ink ejection ratio is not uniform, for example, if there are two solid image portions with dark printing, the temperature distribution curve C2 is obtained. As described above, in uniform ink discharge, the temperature distribution can be estimated by measuring the temperature sensor corresponding to a small number of nozzles. However, for accurate temperature distribution estimation, the temperature sensor over the entire range can be estimated. Measurement is required. However, since the temperature change rate with respect to the nozzle row direction is comparatively smooth, the temperature distribution in the nozzle row direction can be estimated if the average value of the temperature of several nozzles to several tens of nozzles is obtained.

  FIG. 6 is a diagram showing the timing of each signal when the recording paper ST is conveyed by the ink jet recording apparatus PR1 and printing is performed.

  The control unit 20 outputs heat pulses 63, 64, 65, etc. to the ink jet recording head at desired intervals in the printing section, and discharges ink. The acquisition of temperature data for controlling the ink discharge amount is performed using the heat pulse output.

  In the temperature data acquisition section 66, the temperature distribution in the nozzle array direction can be read at high speed using the reading circuit connection of the plurality of temperature sensors, and the temperature distribution as shown in FIG. 5 can be obtained. When the temperature rises during printing and the discharge amount increases, the heat pulse width is reduced after the heat pulse 64, and the discharge amount is made constant. Similarly, the result in the temperature data acquisition section 67 is reflected in the heat pulse width after the heat pulse 65.

  When the printing section ends, the control unit 20 acquires temperature data for non-ejection detection. In this example, the temperature data 68 is acquired by printing on the transport belt 2 when there is no recording paper. Since temperature data for each nozzle is required, data is acquired using the reading circuit connection of the single temperature sensor. The non-ejection detection may be performed during printing.

  If each means in the above embodiment is replaced with a process, the above embodiment is an example of a method for driving the ink jet recording apparatus.

1 is a cross-sectional view illustrating a schematic configuration of an ink jet recording apparatus PR1 that is Embodiment 1 of the present invention. It is a block diagram which shows the control structure of inkjet recording device PR1. It is a figure which shows the structure around the ink discharge port of the inkjet recording head in inkjet recording device PR1. It is a figure which shows the inkjet recording device PR1 comprised by 4 nozzles. It is a figure which shows the temperature distribution figure of the chip | tip on an inkjet recording head. It is a figure which shows the timing of each signal when recording paper ST is conveyed with the inkjet recording device PR1, and printing was performed. It is a figure which shows the conventional inkjet recording device PR2 comprised by 4 nozzles.

Explanation of symbols

PR1 ... inkjet recording apparatus,
20 ... control unit,
30. Inkjet recording head,
31 to 34: recording head,
43. Head chip,
51-54 ... temperature sensor,
55 ... Constant current source,
SW1, SW2 ... Analog switches,
SS1, SS2 ... selection signal,
60 ... operational amplifier,
70: Signal selection means.

Claims (8)

An ink jet recording head comprising a thermal energy converter and ejecting ink using thermal energy generated from the thermal energy converter;
Timing control means for controlling the timing of applying the ejection pulse;
A plurality of independent temperature detecting means for individually detecting temperatures in the vicinity of each of the plurality of ink discharge nozzles formed inside the ink jet recording head, wherein the temperature detecting means are connected in series to each other. When;
A signal selection unit that selects at least one temperature detection unit from among the plurality of temperature detection units connected in series to each other, and selects and outputs a temperature detection value corresponding to the selected temperature detection unit;
An ink jet recording apparatus comprising: In claim 1,
The temperature detection means is a means that is driven by a constant current source input from the outside of the ink jet recording head and outputs the voltage across the element built in the temperature detection means as a temperature detection value. An ink jet recording apparatus. In claim 1,
An ink jet recording apparatus, wherein the element incorporated in the temperature detecting means is a resistor. In claim 1,
The signal selection unit selects and outputs a temperature detection value corresponding to the temperature detection unit selected according to the first selection signal and the second selection signal input from the outside of the ink jet recording head. An ink jet recording apparatus, characterized in that: In claim 4,
The temperature detection value output in response to the first selection signal is a value used for non-ejection detection of each nozzle. In claim 4,
The temperature detection value output in response to the second selection signal is a value used as a control value for discharge amount control for controlling the discharge amount of the ink jet recording head. In any one of Claims 1-6,
An ink jet recording apparatus, wherein the recording head is a recording head that ejects ink using thermal energy, and has a thermal energy converter for generating thermal energy applied to the ink. A step of providing a thermal energy converter, and an inkjet recording head ejecting ink using thermal energy generated from the thermal energy converter;
A step in which the timing control means controls the timing of applying the ejection pulse;
A plurality of independent temperature detecting means for individually detecting temperatures in the vicinity of each of the plurality of ink discharge nozzles formed inside the ink jet recording head, wherein the plurality of temperature detecting means are connected in series with each other. Selecting at least one of the temperature detection means, and selecting and outputting a temperature detection value corresponding to the selected temperature detection means;
A method for driving an ink jet recording apparatus, comprising:

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