JP2017030270A - Recording head, recording device and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems of an inkjet recording device that multiple temperature sensors have to be disposed inside a recording head in order to achieve high precision recording control, and that an area of the recording head is enlarged due to the temperature sensors and wiring, thus constituting cost increasing factors.SOLUTION: Sub-heaters arranged along a nozzle array are divided into plural patterns, and a resistance value of each pattern is measured at a timing when the sub-heaters are not heated, and from a result thereof, a temperature of the pattern is obtained.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a recording head, a recording apparatus, and a control method therefor, and more particularly to, for example, an inkjet recording head, a recording apparatus that performs recording using the recording head, and a control method for the apparatus.

  In a thermal ink jet recording head (hereinafter referred to as a recording head), the viscosity and surface tension of the ink change depending on the temperature. Therefore, the amount of ink ejected changes depending on the temperature of the recording head, and the recorded image formed on the recording medium changes. Concentration may change. Alternatively, there is a case where an image is not recorded without ejecting ink from the recording head. In order to avoid such a state, conventionally, in order to control the ink discharge amount, the self-temperature increase of the recording head is accurately read by the temperature sensor, and the driving control of the recording head is performed according to the temperature. .

  In addition, since the recording head is becoming longer and larger in order to improve the recording speed and the temperature in the recording head is not uniform, it is required to perform accurate temperature control. For this reason, for example, as proposed in Patent Document 1, a plurality of temperature sensors are arranged in the recording head to detect the temperature for each area, and the recording head is driven according to the temperature for each area. Control is in progress. On the other hand, since the recording head is required to be within a certain temperature range for ink ejection, for example, as proposed in Patent Document 2, a sub heater is arranged on the outer periphery of the nozzle row of the recording head to A technique for heating the recording head before the start of the discharge is known.

JP 2004-017457 A JP2013-111923A

  In recent years, in order to achieve higher image quality of recorded images, more precise recording head drive control has been demanded, so the temperature detection area has been further subdivided, and many temperature sensors have been attached accordingly. It has become necessary to place it inside the recording head. As a result, many wirings for transferring outputs from a large number of temperature sensors arranged in the recording head to the recording apparatus have been required. For this reason, the number of layers and the area of the semiconductor substrate of the recording head increase, which causes an increase in cost. Since the cost is determined by the number of semiconductors that can be taken out from a single wafer, the increase in area has a great influence on the cost.

  The present invention has been made in view of the above conventional example, and provides a recording head capable of accurate temperature detection with an inexpensive configuration, a recording apparatus capable of accurately controlling the driving of the recording head, and a control method therefor The purpose is to do.

  In order to achieve the above object, the recording head of the present invention has the following configuration.

  That is, a plurality of nozzles, N resistors arranged along the direction in which the plurality of nozzles are arranged, and a current supplied to one end of each of the N resistors according to a control signal input from the outside And a switch for selecting any one of the N resistors in accordance with the control signal and outputting a potential difference between both ends of the selected resistor. .

  According to another aspect of the present invention, the resistance value of the selected resistor is obtained from the potential difference output by the recording head having the above-described configuration and the output means, and the selected value is obtained from the obtained resistance value. According to the result of the comparison by the comparison means by the calculation means for calculating the temperature of the resistor, the comparison means for comparing the temperature of the N resistors calculated by the calculation means with a predetermined temperature, And a control unit that controls to start recording by the recording head.

  According to another aspect of the present invention, there is provided a method for controlling a recording apparatus that performs recording using the recording head having the above-described configuration, wherein the resistance value of the selected resistor is determined from the potential difference output by the output means. A calculation step of calculating the temperature of the selected resistor from the determined resistance value, and a comparison comparing the temperature of the N resistors calculated in the calculation step with a predetermined temperature And a control step of controlling to start recording by the recording head according to the comparison result in the comparison step.

  Therefore, according to the present invention, it is possible to detect temperatures of a plurality of regions in the recording head without providing a temperature sensor in the recording head. Further, since the circuit related to the temperature sensor can be eliminated, the recording head can be made compact accordingly, and the cost of the recording head can be reduced as compared with the case where the temperature sensor is used.

1 is a perspective view schematically showing a configuration of a recording apparatus that performs recording using an ink jet recording head that is a typical embodiment of the present invention. FIG. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. FIG. 4 is a diagram illustrating an example of an arrangement of nozzle rows and sub heaters of a recording head. FIG. 4 is an enlarged view of a part of the nozzle arrangement shown in FIG. 3. It is a block diagram which shows the structure of a temperature detection circuit. It is the figure which showed the temperature detection circuit specialized in one sub heater pattern. It is a figure which shows the structure of the temperature detection specialized to one selected pattern. It is a flowchart which shows a sub heater drive control operation when a recording command is received with recording data from the external device. 6 is a timing chart showing ink discharge control. It is a flowchart which shows the temperature detection in recording, and the process of a subheater heating.

  Hereinafter, embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. Furthermore, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a medium is processed regardless of whether or not it is manifested so that a human can perceive it visually.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, the term “ink” should be interpreted broadly in the same way as the definition of “recording” described above. When applied to a recording medium, it forms an image, a pattern, a pattern or the like, or processes the recording medium. It represents a liquid that can be subjected to the treatment. Examples of the ink treatment include solidification or insolubilization of the colorant in the ink applied to the recording medium.

  Furthermore, unless otherwise specified, the “recording element (recording element or nozzle)” collectively refers to an ejection port or a liquid path communicating with this and an element that generates energy used for ink ejection. .

  FIG. 1 is an external perspective view schematically showing a configuration of a recording apparatus 50 that performs recording using an ink jet recording head (hereinafter referred to as a recording head), which is a typical embodiment of the present invention.

  The recording apparatus 50 uses a serial scanning method in which recording is performed by discharging ink onto the recording medium P while the carriage 53 on which the recording head 54 is mounted moves in the direction of arrow A (main scanning direction) by the guide shafts 51 and 52. Device. The carriage 53 reciprocates in the main scanning direction by a driving force transmission mechanism such as a carriage motor and a belt for transmitting the driving force. After the recording medium P is inserted from the insertion port 55 provided at the front end of the apparatus, the transport direction is reversed, and then the recording medium P is transported by the transport roller 56 in the direction of arrow B (sub-scanning direction).

  The recording apparatus 50 moves the recording head 54 in the main scanning direction, ejects ink toward the recording area of the recording medium P on the platen 57, and moves the recording medium P by a distance corresponding to the recording width. The carrying operation for carrying in the sub-scanning direction is repeated. As a result, images are sequentially recorded on the recording medium P.

  A recovery unit 58 is provided at the left end of the movement area of the carriage 53 so as to face the nozzle row forming surface of the recording head 54 mounted on the carriage 53. The recovery unit 58 includes a cap for capping the nozzle row of the recording head 54 and a suction pump (not shown) that can introduce negative pressure into the cap. With this suction pump, negative pressure is generated in the cap covering the nozzle row, whereby the ink is sucked and discharged from the nozzle row, and a recovery process is performed in order to maintain good ink ejection performance of the recording head 54. Since the recovery process is a known technique, further description is omitted.

  FIG. 2 is a block diagram showing a control configuration of the recording apparatus 50.

  As shown in FIG. 2, the control of the recording apparatus 50 is executed by a control unit 301 equipped with a CPU. A ROM 802, a RAM 803, a buffer memory 804, a PC I / F control unit 805, and an operation unit 807 are connected to the control unit 301 through a system bus 808. The ROM 802 stores a control program for controlling the entire apparatus, and the RAM 803 is used for processing operations for the CPU to control various operations. The buffer memory 804 buffers recording data transferred from an external device such as a personal computer (PC), or buffers recording data obtained by converting the recording data for recording by the recording head 54. A PC I / F control unit 805 is an interface for communicating with an external device such as a PC via a connector 806, and an operation unit 807 is used by a user to operate the recording device 50.

  As shown in FIG. 2, energy for ink ejection is supplied from the power source 810 to the recording head 54, and the energy is controlled to be opened and closed by a control unit 301 by a switch 809. Electric power is supplied from a power source 303 to a sub-heater (described later) of the recording head 54. The power is controlled to open and close by the control unit 301 by the switch 305.

  Further, the recording head 54 is supplied with a recording data signal 811 used for recording, an ejection driving signal 812 for controlling ejection of ink from the recording head 54, and a switching signal 308 to be described later. The recording head 54 is PWM controlled according to temperature information (output of the A / D converter 309), the number of nozzles that are driven simultaneously, and the like. The motor control unit 815 is driven and controlled by a command from the control unit 301 with respect to the conveyance motor 816 for conveying the recording medium P and the carriage motor 817 for moving the carriage 53 mounted with the recording head 54.

  Further, as will be described in detail later, a constant current from a constant current source 304 is supplied to the recording head 54, and a signal amplified by the differential amplifier 310 is input to the A / D converter 309.

  Next, a method for detecting the temperature of the recording head used for driving control of the recording head will be described.

  FIG. 3 is a diagram showing an example of the arrangement of nozzle rows and sub heaters of the print head.

  In the example shown in FIG. 3, the recording head 54 has three nozzle rows 102 in which a plurality of nozzles are arranged in the same direction, and a sub-heater 101 is arranged beside each nozzle row. The nozzle row 102 is provided for each ink color to be ejected (cyan, magenta, yellow, etc.). In this example, there are three rows, but the number of ink colors to be ejected increases as the number of ink colors to be ejected increases.

  The sub-heater 101 is arranged as a finely divided pattern along each nozzle row 102 as shown in FIG. That is, the inside of the recording head is divided into several areas, and a pattern is arranged in each area. In the example shown in FIG. 3, the sub heater 101 is divided into N patterns 101-1, 101-2,..., 101-N in the nozzle arrangement direction. As a method for driving the recording head, for example, a method in which the nozzle row is divided into several blocks and time-division driving is known, but a group region composed of a plurality of adjacent nozzles in the time-division driving is known. You may arrange | position the pattern mentioned above for every.

  In the following description, when referring to the entire N patterns, the sub-heater 101 is referred to, and when referring to individual pattern inputs, the pattern 101-i (i = 1 to N) is referred to.

  FIG. 4 is an enlarged view of a portion surrounded by a broken line 103 in FIG.

  As shown in FIG. 4, each nozzle row is formed of a plurality of nozzles arranged in a staggered manner.

  FIG. 5 is a block diagram showing a circuit configuration relating to temperature detection of the print head in the control configuration shown in FIG.

  A control unit 301 that controls the entire recording apparatus 50 executes drive control of the recording head based on the output result of the temperature detection circuit. The sub-heater 101 shown in FIGS. 3 to 4 is driven by a power source 303 and is ON / OFF controlled by opening / closing a switch 305 controlled by the control unit 301. When the switch 305 is closed, a current is supplied from the power source 303 to one end of the sub heater 101 to heat the sub heater 101. In this case, current is supplied to all N patterns 101-1 to 101 -N of the sub-heater 101. A limiting resistor 307 is connected to the sub heater 101 in series.

  As will be described later with reference to FIG. 7, the switch 302 switches whether the sub heater 101 is connected to the path of the heating power source 303 or the constant current source 304 for detecting the resistance value. Then, the sub heater 101 can be connected to the constant current source 304 in accordance with an instruction of the switching signal 308 from the control unit 301. The constant current source 304 supplies a constant current to the pattern selected by the sub heater 101 by the selector 311 in order to detect the temperature of the recording head 54. A selector (SEL) 311 connects each pattern of the sub-heater 101 and selects any one of the sub-heaters 101 in accordance with an instruction of a switching signal 308 from the control unit 301.

  As described above, the switch 302 and the selector (SEL) 311 are switched in synchronization with the same switching signal 308, and thus operate so as to select any one pattern of the sub-heater 101 and detect its resistance value. The switch 306 is ON / OFF controlled by the control unit 301 to prevent a current from flowing from the power source 303 when the pattern of the sub heater 101 is heated.

  The differential amplifier (AMP) 310 amplifies the potential difference between both ends of the selected pattern of the sub heater 101 by the switching signal 308, the switch 302, and the selector (SEL) 311. The A / D converter 309 converts the analog voltage output from the differential amplifier (AMP) 310 into digital data and outputs the digital data to the control unit 301. The differential amplifier (AMP) 310 amplifies the potential difference appearing at both ends of the selected pattern of the sub heater so that the influence of the quantization error has no influence on the temperature control in accordance with the resolution of the A / D converter 309. To do.

  FIG. 6 is a diagram showing a temperature detection configuration specialized for one selected pattern 101-1 in the sub-heater 101.

Here, a temperature detection method using the pattern 101-1 of the sub-heater 101 will be described with reference to FIG. In this example, a differential amplifier circuit using the differential amplifier 310 as an operational amplifier is shown. The differential amplifier circuit is not limited to this example. Each pattern of the sub-heater 101 is a resistor. In general, the resistance value R of the resistor varies depending on the temperature T as shown in Equation (1). That is,
R = {K (T−T0) +1} × R0 (1)
K: Temperature coefficient determined by the material of the resistor R0: Resistance value at the reference temperature T0. That is, if the resistance value of the selected pattern of the sub heater is known, the temperature T at that time can be calculated from the equation (1).

In the circuit shown in FIG. 6, a potential difference generated at both ends of the pattern of the sub-heater 101 is detected by flowing a constant current I from the constant current source 304. Therefore, the resistance value R at that time can be obtained by Ohm's law. The potential difference v appearing in the pattern of the sub-heater 101 by the current I output from the constant current source 304 is amplified by the differential amplifier 310 as shown in Expression (2). That is,
V = (R1 / R2) × v (2)
It is. However, R1 = R2 and R3 = R4.

Assuming that (R1 / R2) in equation (2) is a, the resistance value R at that time can be obtained from equation (3) from Ohm's law. That is,
R = V / (a × I) (3)
It is. The control unit 301 calculates the resistance value R from the output result of the A / D converter 309 to obtain the resistance value R, and further obtains the temperature T at that time from the obtained R value according to the expression (1). .

  FIG. 7 is a diagram showing a temperature detection configuration specialized for one selected pattern 101-1 in the sub-heater 101. FIG. 7 particularly shows the configuration when the switch 302 is switched to connect the constant current source 304 and the pattern 101-1. By such switching, a current for detecting the resistance value of the pattern 101-1 flows in the pattern 101-1 of the sub heater 101. Further, the switch 302 switches the power from the power source 303 to connect to the pattern 101-1 by the switching signal 308. Further, when the switch 305 is closed, a current flows through the pattern 101-1, and is heated.

  Next, the sub-heater drive control operation when a print command is received together with print data from an external device will be described with reference to the flowchart shown in FIG. 8 and the time chart shown in FIG.

  Upon receiving the recording command, the control unit 301 disconnects the power source 303 by opening the switch (SW) 305 in step S101 as shown in FIG. This state is shown in FIG.

  Next, in step S102, the switch (SW) 306 is closed, and in steps S103 to S105, the resistance value, that is, the temperature of each of the N patterns of the sub-heater 101 is obtained while sequentially switching the switch 302 and the selector 311. As described above, since the sub-heater 101 is divided into N patterns, i is generally referred to as a parameter in FIG. 8, and i is varied from 1 to N to obtain the temperature of each pattern.

  In step S106, the temperatures of all N patterns are compared with a predetermined threshold value to check whether the temperature is equal to or higher than the predetermined temperature. If it is determined that the temperatures of all N patterns are equal to or higher than the predetermined temperature, the process proceeds to step S109 to start ink ejection control. On the other hand, if it is determined that the temperature of any of the N patterns is lower than the predetermined temperature, the process proceeds to step S107.

  In step S107, the switch (SW) 306 is opened, and the switch 302 switches to the power source 303 side. In step S108, the switch (SW) 305 is closed and the sub heater 101 is heated for a predetermined time. The predetermined time is appropriately increased or decreased depending on the detected temperature. When the predetermined time has elapsed, the process returns to step S101 again, the switch (SW) 305 is opened, and in step S102, the switch (SW) 306 is closed to obtain the pattern temperature. Such processing is repeated until the temperatures of all N patterns fall within a predetermined temperature range. If it is determined that the temperatures of all N patterns fall within the predetermined temperature range, the heating of the sub-heater is terminated and the processing is completed. Advances to step S109 to start ink ejection control. Thereafter, recording by ink ejection starts.

  FIG. 9 is a timing chart showing ink discharge control.

  According to FIG. 9, the transfer of the recording data signal 811 for determining the nozzle that ejects ink within the range of the predetermined period T0 and the ink ejection based on the recording data signal 811 transferred by the ejection driving signal 812 are executed. To do. Since ink ejection is performed after the transfer of the recording data signal 811, the transfer of the recording data signal and the recording timing by the data signal are shifted by one cycle as shown in FIG. Further, the pulse width of the ejection drive signal 812 is determined by PWM control according to the temperature information of the recording head, the number of nozzles to be driven simultaneously, and the like before the next ejection cycle is started.

  FIG. 10 is a flowchart showing temperature detection during recording and heating control processing by the sub heater.

  In step S901, the switch (SW) 305 is opened to disconnect the power source 303 for heating the sub heater, and in step S902, the switch (SW) 306 is closed to measure the resistance value (ie, temperature) of each pattern of the sub heater. To do.

  Thereafter, in step S903, a timer (not shown) is turned on to start measuring time. In step S904, the temperature of one pattern i out of the N patterns of the sub-heater 101 is obtained. In step S905, the switch (SW) 305 is closed and the power source 303 is connected to the pattern i and heated. In step S906, the process waits for a predetermined time T1, and in step S907, the switch (SW) 305 is opened to disconnect the power supply 303 for heating the sub heater. In this way, in steps S905 to S907, heating of the sub heater pattern i is performed for a predetermined time T1.

  Further, in step S908, the process waits for a predetermined time T2, and when the predetermined time T2 elapses, the process proceeds to step S909 to check whether the recording is finished. If it is determined that recording is in progress, the process proceeds to step S910, and the parameter i is incremented by 1 to switch the switching target of the switch 302 and the selection target of the selector 311 to the next pattern of the sub heater. Find its temperature. Such an operation is repeated until the recording is completed.

  The predetermined time T1 is determined by the temperature of the recording head, and is controlled in the range of 0 ≦ T1 <T2. If the temperature of the recording head is equal to or higher than the predetermined temperature, the sub-heater pattern is not heated at T0 = 0. If the temperature is equal to or lower than the predetermined temperature, the predetermined time T1 is within a range not exceeding the time T2. Is determined and the pattern of the sub-heater is heated.

  Therefore, according to the embodiment described above, by measuring the resistance of the N patterns (resistors) provided along the arrangement direction of the nozzles of the recording head, a temperature sensor is not provided in the recording head. It is possible to detect temperatures in a plurality of areas in the recording head. Further, since there is no need to provide a circuit related to the temperature sensor, the print head substrate can be made compact accordingly, and the cost of the print head can be reduced as compared with the case where the temperature sensor is used.

  In the embodiment described above, the switch 302 and the selector 311 are controlled by the same switching signal 308. However, the present invention is not limited to this. For example, the control signal of the switch 302 may be newly set and further finely controlled, so that the heating control may be individually performed on a plurality of sub heater patterns. In this case, the switch 302 may be connected to the power source 303 only for the pattern to be heated by the sub heater. Therefore, the sub-heater heating control may be individually executed based on the detected temperature. Use the nozzle group when there is a large temperature difference depending on the location of the substrate of the recording head, or when the nozzle group in an area during recording is not used (that is, when the temperature of that part is low). Heating of the area that has not been performed may be performed.

  Although the recording apparatus used in the embodiments described above is a single-function apparatus, the present invention is not limited to this. For example, a multi-function printer (MFP) equipped with a scanner function, a copying function, a facsimile function, etc. may be used.

301 control unit, 302 switch, 303 sub-heater driving power source, 304 constant current source,
307 limiting resistor, 308 switching signal, 309 A / D converter, 310 differential amplifier,
311 selector

Claims (12)

Multiple nozzles,
N resistors arranged along the direction in which the plurality of nozzles are arranged;
A switch for supplying a current to one end of each of the N resistors in accordance with a control signal input from the outside;
A recording head comprising: output means for selecting any one of the N resistors in accordance with the control signal and outputting a potential difference between both ends of the selected resistor. The recording head is an ink jet recording head that performs recording by discharging ink,
The recording head according to claim 1, further comprising a plurality of nozzle rows each including a plurality of nozzles in order to eject ink of a plurality of colors.   The recording head according to claim 2, wherein the N resistors are arranged along each of the plurality of nozzle rows. The recording head according to any one of claims 1 to 3,
A calculating means for calculating a resistance value of the selected resistor from the potential difference output by the output means, and calculating a temperature of the selected resistor from the determined resistance value;
Comparing means for comparing the temperature of the N resistors calculated by the calculating means with a predetermined temperature;
And a control unit that controls to start recording by the recording head according to a result of comparison by the comparison unit. The control means includes
If it is determined by comparison by the comparison means that the temperatures of all the N resistors are equal to or higher than the predetermined temperature, control is performed to start recording by the recording head;
If it is determined by comparison by the comparison means that the temperature of any of the N resistors is less than the predetermined temperature, a current is supplied to the N resistors using the control signal. The recording apparatus according to claim 4, wherein the recording apparatus is controlled to supply the recording medium. A first power source for heating the N resistors by supplying current to the N resistors via the switch;
A constant current second power source for supplying a current for obtaining a resistance value of the N resistors through the switch in order to calculate a temperature of the N resistors; The recording apparatus according to claim 4 or 5.   The control means controls to supply current from the first power supply or the second power supply to the N resistors using the control signal. The recording device described.   The control means inputs the control signal to the output means, selects the N resistors one by one, and further controls the operation of the calculating means to obtain the temperatures of the N resistors. The recording apparatus according to claim 7, wherein the recording apparatus is controlled.   The calculating means supplies a current to the N resistors from the first power supply, and switches the switch after the N resistors are heated, and the N power supplies from the second power supply. The recording apparatus according to claim 8, wherein the temperature of the selected resistor is calculated by supplying a current to the resistor.   The recording apparatus according to claim 4, wherein the control unit performs comparison by the comparison unit at the start of recording by the recording head.   The control means controls opening and closing of the switch during recording by the recording head and supplies current to the N resistors for a predetermined time while heating the N resistors. , Inputting the control signal to the output means, selecting the N resistors one by one, and controlling the operation of the calculating means to obtain the temperature of the N resistors. The recording apparatus according to claim 4, wherein the recording apparatus is a recording apparatus. A method of controlling a recording apparatus that performs recording using the recording head according to any one of claims 1 to 3,
Calculating a resistance value of the selected resistor from the potential difference output by the output means, and calculating a temperature of the selected resistor from the determined resistance value;
A comparison step of comparing the temperature of the N resistors calculated in the calculation step with a predetermined temperature;
And a control step of controlling to start recording by the recording head according to a result of comparison in the comparison step.

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