JP5658494B2 - Head substrate, recording head using the head substrate, and recording apparatus using the recording head - Google Patents

Description

  The present invention relates to a head substrate provided with a temperature detection element, a recording head using the head substrate, and a recording apparatus using the recording head.

  An ink jet printer is a printer that forms an image on a recording medium by ejecting ink onto the recording medium with a heater or a piezoelectric element. In the thermal ink jet method using a heater, ink droplets are ejected by the pressure of bubbles generated by heating ink with a heater. On the other hand, in the piezo method using a piezoelectric element, ink is pushed out by the piezoelectric element. The electrical energy supplied to the heater and the piezoelectric element is converted into thermal energy or dynamic energy. The conversion is performed in the recording head. A head substrate manufactured by a semiconductor manufacturing process to be mounted on the recording head has variations in conversion efficiency due to manufacturing variations, temperature characteristics, and the like. In addition, variations in ink heat capacity, viscous resistance, etc. also affect conversion efficiency. Therefore, even if the same electric energy is input to the recording head, the amount of ink ejected from the recording head varies.

  By grasping in advance the manufacturing variation of the head substrate and the variation in the ink characteristics, it is possible to adopt a driving method according to that to some extent. On the other hand, the temperature of the recording head varies depending on the usage situation. For this reason, a method has been proposed in which the temperature of the recording head is detected during use, and the ink discharge amount is controlled based on the detection result. For example, the methods disclosed in Patent Document 1 and Patent Document 2 are so.

  Also, the purpose of acquiring the temperature of the recording head has changed with the times. Initially, the purpose is to detect an abnormal situation such as the recording head being destroyed. By periodically acquiring the temperature of the recording head, the recording head is judged to be abnormal and the driving of the recording head is stopped. It was what controls.

  Thereafter, the temperature detection of the recording head has been performed to improve the image. The temperature of the recording head is measured for each page recording or for each scanning of the recording head, so that the state of the head at each time is judged and the recording of the next page or the next scanning is performed. Control has been performed to change the drive method of the recording head.

  Furthermore, as recording speed increases and image quality increases, the effect of an abrupt temperature rise in one scan of the recording head on the image cannot be ignored, and temperature acquisition and driving method change during one-scan recording can be performed. It has come to be required.

  Here, a conventional method for measuring the head temperature and its measurement configuration will be outlined.

  FIG. 5 is a block diagram showing a conventional head temperature measurement configuration.

  First, the outline of the recording operation will be described.

  As shown in FIG. 5, an IC 51 is provided on the main substrate 24 of the recording apparatus, and a head substrate mounted on the recording head 5 mounted on the carriage by the recording data signal (HDATA) from the IC 51 in synchronization with the clock signal (HCLK). 25. Further, a latch signal (HLATCH) and a heat enable signal (HENB) are also transferred from the IC 51 to the head substrate 25. These signal transfers are performed via a flexible flat cable (FFC) 26 that connects the carriage substrate 21 mounted on the carriage and the main substrate 24.

  The transferred recording data signal (HDATA), clock signal (HCLK), and latch signal (HLATCH) are received by the logic circuit 53 of the head substrate 25. On the other hand, when recording is performed by driving the heater 56 of the recording head 5, the AND circuit 54 calculates the logical product of the head enable signal (HENB) and the output signal from the logic circuit 53 to generate a heat signal. Then, the heater driver 55 is driven by the heat signal, and the heater 56 is driven.

  Although only one heater is shown in FIG. 5, there are the same number of heaters as the number of nozzles of the recording head. When the recording head is driven, a current flows through the heater 56, and the current flows into the GND of the head substrate.

  FIG. 6 is a time chart and signal waveforms of various signals supplied to the recording head. As can be seen from FIG. 6, the recording data signal (HDATA) is transferred in synchronization with the clock signal (HCLK). When the transfer is completed, a latch signal (HLATCH) is transferred, and a recording data signal is held by a latch circuit (not shown) of the logic circuit 53. Further, recording based on the recording data signal transferred in the previous cycle is executed at the transfer timing (A in FIG. 5) of the heat enable signal (HENB).

  Next, the configuration of head temperature measurement will be described.

  FIG. 7 is a diagram showing temperature characteristics of the diode sensor.

  The head temperature is measured by a diode sensor 57 provided on the head substrate 25. As shown in FIG. 7, the forward potential (VF) of the diode sensor changes with temperature fluctuation (environmental temperature Ta). Although there are variations in characteristics depending on the forward current (If) etc., these characteristics are generally shown, and when the temperature rises, the forward voltage tends to decrease, and the temperature change can be read from the change in the forward voltage. .

  In the conventional configuration, a signal (ADin) obtained by level-converting the anode signal (DIODE_A) of the diode sensor via the level shift circuit 58 is input to the A / D converter port (AD) of the IC 51 and read.

JP-A-7-256894 JP-A-5-125929

  However, although the configuration of the conventional example is a simple configuration, there are the following problems.

(1) It is difficult to measure temperature when the heater of the recording head is driven. As described above, when the heater 56 is driven, a current flows into the GND of the head substrate 25. Since the cathode terminal of the diode sensor 57 for detecting the temperature is connected to the GND of the head substrate, if a large current for driving the recording head flows into the cathode terminal of the diode sensor 57, the potential of the anode terminal is affected. Effect. As a result, the read data is affected. For example, as shown in the timing B of FIG. 6, when the heater 56 is driven by supplying the heat enable signal (HENB), the potential of the anode signal (DIODE_A) of the diode sensor 57 greatly oscillates.

  For this reason, if it is attempted to read the head temperature while the heater is being driven, heat timing cannot be avoided.

(2) Problem of Crosstalk on Transmission Line FIG. 8 is a diagram showing an equivalent circuit having a configuration used for measuring the head temperature.

  The recording data signal (HDATA) is output from the IC 51, amplified by the output buffer 61, and used to drive the heater driver 55 disposed on the head substrate 25 via the FFC 26. As a result, the heater 56 is driven.

  On the other hand, the output of the diode sensor 57 on the head substrate 25 is a signal with high impedance and small amplitude, and is easily affected by harmonic noise. The FFC 26 has resistance (R) and inductance (L) components, and adjacent signals are coupled by impedance having resistance (R) and capacitor (C) components. The adjacent signal line here refers to a signal line adjacent to the parallel wiring in the wiring member such as the FFC 26, a signal line adjacent when the FFC 26 is folded, or a signal line adjacent to the harness. The junction capacitance of these adjacent signal lines changes, and the adjacent signal lines are easily affected by crosstalk.

  In FIG. 8, for example, when a high-frequency signal, that is, a signal having a rectangular waveform such as a recording data signal (HDATA) flows through the signal line 62, the signal includes high-frequency noise as understood by Fourier transform. For this reason, noise is superimposed on the anode signal (DIODE_A) via the inductance (L) component of the signal line 63 that is close by electromagnetic induction. Further, when the junction capacitance between adjacent signals is small, for example, when the pitch of the FFC 26 is narrow or when the FFC 26 is in close contact, noise is superimposed via the junction capacitance component (broken line in FIG. 8).

  As a result, noise is superimposed on the anode signal (DIODE_A) transferred through the adjacent signal line when recording data is transferred. As a result, as shown at timing C in FIG. 6, the input signal (ADin) from the diode sensor changes greatly.

  As described above, in the conventional configuration, since the output signal of the diode sensor is a signal having a high output impedance and a small amplitude, it is possible to avoid noise from being superimposed at the timing when an external signal such as a recording data signal is transferred. Can not.

  As described above, in the conventional configuration, the head temperature cannot be accurately detected at the timing when the recording head scans while ejecting ink because the diode sensor signal is buried in noise. For this reason, in the conventional configuration, the head temperature is acquired at a timing such as before the recording on the recording medium of the next page after recording on the recording medium of the next page is completed during the recording scan.

  If the head temperature acquisition cycle is acceptable even if it is relatively long, the conventional technology was able to cope with it, but if it is necessary to frequently acquire the head temperature in a shorter cycle, There is a problem that this technology cannot handle it.

  The present invention has been made in view of the above-described conventional example, and provides a head substrate capable of accurately detecting the head temperature at a shorter interval, a recording head using the head substrate, and a recording apparatus. It is said.

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

That is, an element that generates energy used to eject liquid, a driver that drives the element , a logic circuit that latches a recording data signal transferred in synchronization with a clock signal using a latch signal, and a head temperature And a temperature detection element for detecting the head temperature data, the head substrate including a latch circuit for latching the head temperature data detected by the temperature detection element by the latch signal, and the head temperature data latched by the latch circuit. It is characterized by output to the outside.

  According to another aspect of the present invention, a recording head using the head substrate described above is provided.

Further, according to still another aspect of the present invention, there is provided a recording apparatus in which the recording head described above is mounted on a carriage, and recording is performed by the recording head while scanning the carriage. A carriage substrate connected to a head substrate of the recording head; a control circuit that controls the operation of the recording head; and a flexible flat cable that connects the control circuit and the carriage substrate. The signal line includes a plurality of signal lines, the clock signal, the recording data signal, and the latch signal are transferred by a part of the plurality of signal lines, and the element is driven by another part of the plurality of signal lines. An enable signal is transferred, and the head temperature data is transferred by another part of the plurality of signal lines. Wherein the carriage substrate comprising a recording apparatus characterized by being provided with an impedance conversion circuit to reduce the impedance of the signal line for transferring head temperature data output from the head substrate.

  Therefore, according to the present invention, it is possible to avoid the transfer timing of the recording data signal and the heater driving timing during the recording operation, to acquire the head temperature data, and to reduce the noise due to the crosstalk in the signal transmission path in which the signal lines are close to each other. There is an effect that can be. This makes it possible to obtain high-quality head temperature data even in an environment where signal transmission occurs at high speed or many signal lines are dense, and recording control can be performed more accurately than the acquired head temperature data. Become.

1 is a schematic perspective view illustrating a configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. It is a block diagram which shows the measurement structure of head temperature. FIG. 6 is a time chart and signal waveforms of various signals supplied to the recording head and output signals from a diode sensor of the recording head. It is a block diagram which shows the measurement structure of the conventional head temperature. FIG. 6 is a diagram illustrating a time chart and signal waveforms of various signals supplied to the recording head. It is a figure which shows the temperature characteristic of a diode sensor. It is a figure which shows the equivalent circuit of the structure used in order to measure head temperature.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. However, the relative arrangement and the like of the constituent elements described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

  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, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, it is used for formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

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

  FIG. 1 is a schematic perspective view showing an overall image of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) which is a typical embodiment of the present invention. In this recording apparatus, a replaceable ink tank is mounted on the carriage 6. That is, the ink main tank 1 is provided outside the carriage 6, and the ink is supplied to the sub tank 2 mounted on the carriage 6 by the tube 3.

  In this recording apparatus, as shown in FIG. 1, the ink is supplied from the main tank 1 on the front side of the apparatus to the sub tank 2 of the carriage 6 through the tube 3 by the ink circulation unit 4. The ink circulation unit 4 controls the flow of ink by, for example, constricting the tube with an actuator such as a motor, and circulates the ink by determining whether the ink supply is appropriate or not according to the ink remaining amount or the recording mode of the sub tank 2. .

  A recording medium 15 such as recording paper is placed on an automatic paper feeding mechanism (ASF) 10 and is transported by the driving force of the transport motor 14 and the paper feed motor 12. The carriage motor 13 scans the carriage 6 left and right, and ink is ejected from an ink jet recording head (hereinafter, recording head) 5 to perform recording.

  The above is the outline of the recording operation.

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

  An ASIC (control circuit) 16 composed of a CPU and dedicated hardware controls the entire recording apparatus by controlling various motors while accessing an NVRAM 17 storing a program, a RAM 18 used as a work area, and a ROM 19 storing control information. doing. The carriage 6 includes the carriage substrate 21 and is connected to the head substrate 25 mounted on the recording head 5 by a connector. Ink is supplied to the recording head 5 from the sub tank 2.

  The carriage substrate 21 is connected to a main substrate 24 on which the ASIC 16 is mounted by a flexible flat cable (FFC) 26. A motor driver IC 27 for driving the motor is mounted on the main board 24. The motor driver IC 27 drives various motors under the control of the ASIC 16. The various motors include an ink circulation motor 28 that drives a pump that circulates ink, a carriage motor 13, a conveyance motor 14, a paper feed motor 12, a recording paper pickup, and a maintenance motor 29 for a recording head maintenance operation.

  The ASIC 16 takes in and detects detection signals from the encoder 33 and various sensors 34. In addition, an interface 35 for connecting to an external device such as a PC or a digital camera is provided. AC 100 to 240 V AC, which is a commercial power supply, is converted into a DC voltage by the AC / DC converter 36 and supplied to the main board 24. The voltage is converted by a DC / DC converter (not shown) into a logic voltage used for the ASIC 16 or the like or a high-accuracy analog power source for sensors as required. The main board 24 includes a clock IC 37 and a backup battery 38, and stores time information of various events in the NVRAM 17 and is used for various controls. A panel substrate 39 is provided for user operation. The panel substrate is provided with an LCD 40, a switch 41, and an LED 42, and is used to inform the user of the state of the recording apparatus and to operate the recording apparatus.

  FIG. 3 is a block diagram showing a configuration for measuring the head temperature according to this embodiment. In FIG. 3, the same configurations and signals as those already described in the conventional example are referred to by the same reference numerals and symbols, and the description thereof is omitted.

  FIG. 4 is a time chart and signal waveforms of various signals supplied to the recording head according to this embodiment and output signals from the diode sensor of the recording head.

  The transfer timing of the recording data signal (HDATA), the clock signal (HCLK), and the latch signal (LATCH) is the same as the conventional one. Also, the transfer timing of the heat enable signal is the same as the conventional one.

  Next, the structure of temperature detection according to this embodiment will be described with reference to FIGS. Also in this embodiment, the head temperature is detected by a diode sensor (temperature detection element) 57 mounted on the head substrate 25.

  In this embodiment, a latch circuit composed of an FET 71 and a capacitor 72 is provided on the head substrate 25 so that temperature data can be held. According to the configuration shown in FIG. 3, the latch signal (LATCH) is also input to the gate of the FET 71. On the other hand, the anode of the diode sensor 57 is connected to the source of the FET 71. Accordingly, the latch signal is applied to the gate of the FET 71 when the latch signal is input (that is, the recording data signal is also latched). As a result, a current flows between the drain and source (D-S) of the FET 71, the capacitor 72 is charged by the output from the diode sensor 57, and the temperature data is latched. Then, the charge charged in the capacitor 72 is released and becomes an output signal (latch_out).

  As shown in FIG. 4, the latch timing is the timing when the latch signal (HLATCH) is enabled (timing A in FIG. 4). This timing is the end timing of the transfer of the recording data signal, and is the timing before setting the recording data signal of the next recording period in the logic circuit of the head substrate, so the heater driving timing of the recording head (the timing of FIG. 4). B) Don't hit it. Therefore, it is possible to reliably latch the head temperature data at the timing C in FIG. 4 while avoiding the heater driving timing of the recording head in which noise is superimposed on the anode signal (DIODE_A) of the diode sensor 57 as shown in FIG. is there.

  Since the head substrate 25 is manufactured by a semiconductor manufacturing process, it can be said that the latch circuit including the FET and the capacitor can be easily manufactured.

  Further, according to FIG. 3, in this embodiment, the carriage substrate 21 is provided with the impedance conversion circuit 75, and the impedance of the signal line 76 which is a part of the FFC 26 including a plurality of signal lines is lowered. In the example of FIG. 3, the impedance conversion circuit is configured by a voltage follower circuit including one operational amplifier. Since the voltage follower circuit has a very low output impedance, it is not easily affected by crosstalk even when the signal lines are close as shown in FIG. 8, and noise is superimposed on the diode sensor signal on the signal line. Can be avoided.

  In this way, the head substrate of this embodiment uses a configuration that can be easily formed by a semiconductor manufacturing process, and a circuit that uses a general-purpose analog IC for the carriage substrate enables a low-cost configuration. Become.

  Therefore, according to the embodiment described above, with a simple configuration, it is not affected by crosstalk from adjacent signal lines in the FFC, and further, the transfer timing of the recording data signal from the recording apparatus and the transfer of the heat enable signal Head temperature data can be acquired avoiding timing. Therefore, since the acquired head temperature data is high-quality data that is not affected by noise, it is possible to perform recording control that reflects more accurate temperature data.

  Further, since the head temperature data is acquired in synchronization with the latch timing of the recording data signal, there is an advantage that it is not affected by the high-speed recording data signal transfer.

  In the embodiment described above, (1) a configuration for holding head temperature data on the head substrate is provided, and (2) a configuration for reducing the impedance of a signal line through which the head temperature data passes in an FFC including a plurality of signal lines. Prepare.

  That is, the detection voltage of the diode sensor is held by the latch signal in the latch circuit formed on the head substrate. This latch timing is a timing that avoids the drive timing of the heater of the recording head in the recording operation. Although this timing occurs during scanning of a normal recording head, it is synchronized with the transfer of the recording data signal, so that the head temperature data can be latched without considering the scanning position of the recording head.

  In addition, an impedance conversion circuit for reducing the wiring impedance is provided on the carriage substrate. As a result, a voltage follower circuit composed of an operational amplifier having a relatively large circuit scale for mounting on a head substrate can be configured as an impedance conversion circuit. In this way, noise caused by crosstalk between adjacent signals or adjacent signals on a long wiring path following the impedance conversion circuit can be suppressed. If the impedance of the wiring is large, voltage fluctuations due to the electromagnetic field caused by the proximity signal and the minute current induced by the junction induction become large, greatly affecting the voltage level of the signal, but these effects are reduced by lowering the impedance. It becomes possible.

Claims (7)

An element that generates energy used for ejecting liquid, a driver that drives the element , a logic circuit that latches a recording data signal transferred in synchronization with a clock signal by a latch signal, and a head temperature detection A head substrate including a temperature detecting element that performs
A latch circuit that latches the head temperature data detected by the temperature detection element by the latch signal;
A head substrate that outputs head temperature data latched by the latch circuit to the outside. The temperature sensing element is a diode sensor;
The head substrate according to claim 1, wherein an anode signal from the diode sensor is output as the head temperature data. The latch circuit is composed of an FET and a capacitor,
3. The head substrate according to claim 1, wherein the latch signal is input to a gate of the FET, and the capacitor is charged by a current between a drain and a source of the FET.   A recording head on which the head substrate according to claim 1 is mounted.   The recording head according to claim 4, wherein the recording head is an ink jet recording head. A recording apparatus that mounts the recording head according to claim 4 on a carriage and performs recording by the recording head while scanning the carriage,
A carriage substrate provided in the carriage and connected to a head substrate of the recording head;
A control circuit for controlling the operation of the recording head;
A flexible flat cable connecting the control circuit and the carriage substrate;
The flexible flat cable includes a plurality of signal lines, and the clock signal, the recording data signal, and the latch signal are transferred by a part of the plurality of signal lines, and another part of the plurality of signal lines. A heat enable signal for driving the element is transferred by the above, the head temperature data is transferred by still another part of the plurality of signal lines,
The recording apparatus according to claim 1, wherein the carriage substrate is provided with an impedance conversion circuit that lowers an impedance of a signal line for transferring head temperature data output from the head substrate.   The recording apparatus according to claim 6, wherein the impedance conversion circuit includes a voltage follower circuit.

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