WO2004050370A1

WO2004050370A1 - Recording head and recorder comprising such recording head

Info

Publication number: WO2004050370A1
Application number: PCT/JP2003/015225
Authority: WO
Inventors: Nobuyuki Hirayama
Original assignee: Canon Kabushiki Kaisha
Priority date: 2002-11-29
Filing date: 2003-11-28
Publication date: 2004-06-17
Also published as: EP1579997A1; KR20050087811A; KR20080081970A; CN1717329A; EP1579997A4; JP2004181678A; AU2003302652A1; CN100415519C

Abstract

A recording head having a plurality of recording devices comprises a plurality of switching devices provided corresponding to the respective recording devices, constant current sources provided corresponding to the respective recording devices for applying a constant current, and a current control circuit for controlling constant currents supplied from the constant current sources. The recording devices are driven by constant currents from the constant current sources.

Description

TECHNICAL FIELD A recording head and a recording device provided with the recording head

The present invention relates to a recording head including a plurality of recording elements, and a recording device including the recording head. Background art

An ink jet that generates thermal energy by the heater and nozzle arranged in the nozzle of the recording head, uses the thermal energy to foam ink near the heater and ejects ink from the nozzle to perform recording The head is known. FIG. 11 shows an example of a heater drive circuit in such an ink jet head.

In order to print at high speed, it is desirable to drive as many heaters as possible at the same time and eject ink from many nozzles simultaneously. However, the power supply capability of the power supply of the printer is limited, and the current value that can be passed at one time is limited due to a voltage drop due to the resistance of the wiring from the power supply to the heater. For this reason, time-division driving in which a plurality of heaters are driven in a time-division manner to eject ink is generally performed. In this time-division driving, for example, a plurality of heaters is divided into a plurality of blocks composed of heaters arranged adjacent to each other, and driving is performed so that two or more heaters are not driven simultaneously in each block. Time-sharing eliminates the need to supply large amounts of power at once by suppressing the total current flowing through the heater. The operation of the drive circuit for driving such a heater will be described with reference to FIG.

Heaters 1 1 0 1 u to l 10 l _mx corresponding to each NMO Transistor 1 1 10 2 H to 1 10 2 _M J, as shown in Fig. 11 (x) The blocks to be accommodated are divided into l to m. That is, in block 1, the power supply lines from the power supply pad 1104, a heater 1101 "110 1 are connected in common to _lx, each NMOS transistor 1102 u~l 10 2 i _x, supply 1 104 and the ground 1104 Are connected in series with each of the corresponding transistors 1101 u to 101 _lx , and each of the transistors 1101 „to 1101 _lx is supplied from the control circuit 1105 to the corresponding NMOS transistor 1102 u. when to l 102 control signal to the gate of _lx is applied, the current through the corresponding heater is heated by the flow from the power supply wiring by the NMOS transistors ll OS ^ ll OS i _x is turned on.

FIG. 12 is a timing chart showing the timing for energizing and driving each block of the heater drive circuit shown in FIG.

For example, taking as an example the block 1 of FIG. 11, the control signal VGl~VGx are timing signals for driving the first to X-th heater 1101 u~l 101 _lx belonging to the block 1. That, VGl～VGx shows the waveform of the signal input to the block of the click 1 NMOS transistor ll O Su ll O 2 _lx control terminal (gate one g), when the high level, the corresponding NMO S transistor 1 102 Turns on and turns off the corresponding NMOS transistor when it is at low level. The same applies to other blocks 2 to m. In FIG. 12, each of I hl to I hx indicates a current value flowing through each of the heaters 1101 ^ to 丄 101 _x .

In this way, by sequentially energizing the heaters in each block in a time-division manner, the number of heaters energized and driven in each block can be controlled so as to always be one or less. There is no need to supply a large current to the heater.

FIG. 13 is a diagram showing a layout example of a heater substrate (a substrate constituting a recording head) on which the heater drive circuit of FIG. 11 is formed. This Figure 13 FIG. 11 shows a layout of power supply lines connected from power supply pads 1104 to blocks 1 to m shown in FIG.

The power supply wiring 1 3 0 1 i to 1 3 0 1 _m is individually supplied from the power supply pad 1 1 0 4 to the blocks 1 to _m , and the power supply wiring 1 3 0 2 to 丄 3 0 is supplied from the power supply pad 1 1 0 4. 2 _m is connected. As described above, by setting the maximum number of heaters that are simultaneously driven in each block to 1 or less, the current value flowing through the wiring divided for each block can always be less than the current flowing to one heater. Wear. As a result, even when a plurality of heaters are driven simultaneously, the amount of voltage drop in the wiring in the heater substrate can be kept constant. At the same time, even when multiple heaters are driven simultaneously, the amount of energy input to each heater can be made almost constant.

In recent years, high-speed and high-definition printers have been required, and the recording head of the printer has been increased in density and the number of nozzles has been increased. In terms of speed, it is required to drive as many heaters simultaneously as possible at high speed.

The heater substrate has many heaters and their driving circuits formed on the same semiconductor substrate. For this reason, low-cost MOS-type semiconductor processes that enable high-density and small-sized devices, have simple manufacturing processes, and are used for the formation of drive circuits over the night are used. Furthermore, since it is necessary to reduce the cost by increasing the number of heater substrates that can be obtained from one wafer, it is also required to reduce the size of the heater substrate.

However, as described above, when the number of heaters driven simultaneously is increased, wiring corresponding to the number of simultaneously driven heaters is required in the substrate. For this reason, the number of wirings increases, and when the area of the heat-sink substrate is limited, the wiring area per one wiring decreases and the wiring resistance increases. At the same time, as the number of wirings increases and the width of each wiring becomes narrower, the variation in resistance among the wirings in the heating board also increases. The problem is that the heater board This also occurs in the case of miniaturization, and furthermore, the wiring resistance increases and the resistance variation increases. As described above, since the heater and the power supply wiring are connected in series with the power supply in the heater board, the variation in the wiring resistance and the resistance increases, and the variation rate of the voltage applied to each heater increases. Increase.

If the energy input to the heater is too small, the ejection of the ink becomes unstable, and if it is excessive, the durability of the heater will be reduced. Therefore, in order to perform high-quality recording, it is desirable that the energy input to the heater be constant. However, as described above, when the fluctuation of the voltage applied to the heater is large, the durability of the heater is reduced, and the ink ejection becomes unstable.

In addition, since the wiring outside the heater substrate is common to a plurality of heaters, the voltage drop in the common wiring varies depending on the number of heaters driven simultaneously. In order to stabilize the energy input to each heater against such fluctuations in voltage drop, the energy input to each heater is adjusted by the voltage application time. However, since the voltage drop in the common wiring increases due to the increase in the number of heaters driven at the same time, the time for applying the voltage during the heater drive increases, making it difficult to drive the heater at high speed. ing.

A method for solving such a problem due to fluctuations in the energy input to the heater has been proposed in Japanese Patent Application Laid-Open No. 2001-1991. FIG. 14 shows a heater driving circuit described in Japanese Patent Application Laid-Open No. 2000-191913. Here, constant current sources (Trl4 to Tr (n + 13)) provided for each recording element (Rl to Rn) and switching elements (Ql to Qn) are used to control the heaters (Rl to Rn) with a constant current. It is driven by. With this configuration, it is possible to always drive the heater with a constant current regardless of fluctuations in the voltage drop outside the substrate due to an increase in the number of driving heaters. The constant current source circuits and switching elements required for the same number as the number of heaters occupy the majority of the area of the heater substrate, so reducing the area of this part is important for suppressing the cost of the heater substrate. Since the current flowing through the heater is as high as 50 mA to 200 mA, it may not be possible to reduce the transistor size in order to suppress the voltage drop due to the parasitic resistance of the transistor. In addition, by shortening the wiring from the heater to the switching element and the constant current circuit, the board area can be reduced.Therefore, the constant current source circuit and the switching element should be arranged at the same pitch as the arrangement pitch of the light. Is valid.

However, since such a configuration is made by a semiconductor process using bipolar transistors, in recent years, for example, at a high-density array pitch of 600 dpi or more, a bipolar transistor However, there is a problem that the wiring to the heater is long and the area of the heater substrate is significantly larger than the area of the heater substrate of the conventional driving method. Disclosure of the invention

The present invention has been made in view of the above conventional example, and the feature of the present invention is that even if the number of simultaneous driving of the recording elements increases, high-speed and stable recording is possible, and the area of the heater substrate is increased. It is an object of the present invention to provide a recording head in which cost increase is suppressed without increasing, and a recording apparatus provided with the recording head.

Further, the present invention is characterized in that each recording element is driven by a constant current, and the constant current value can be adjusted so that uniform energy can be applied to each recording element. Another object of the present invention is to provide a recording device provided with a storage device.

Other features and advantages of the present invention will become apparent from the following description made with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the description of the present application, illustrate embodiments of the present invention and, together with the description, explain the principles of the invention.

FIG. 1 is a circuit diagram showing an example of a heater drive circuit provided in the print head according to the first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of a drive circuit per heater according to the first embodiment of the present invention.

FIG. 3 is a timing chart illustrating the operation timing of the circuit of FIG.

FIG. 4 is a circuit diagram showing an example of a heater drive circuit provided in the recording head according to the second embodiment of the present invention.

FIG. 5 is a characteristic diagram of the NMOS transistor used in this embodiment. FIG. 6 is a circuit diagram showing conditions for measuring characteristics of the NMOS transistor according to the second embodiment of the present invention.

FIG. 7 is a circuit diagram showing an example of a heater drive circuit provided in the recording head according to the third embodiment of the present invention.

FIG. 8A is a characteristic diagram of the NMOS transistor according to the second embodiment, and FIG. 8B is a circuit diagram showing the characteristic measurement conditions of the NMOS transistor.

FIG. 9 is a circuit diagram showing an example of a head drive circuit provided with a recording head according to the fourth embodiment of the present invention.

FIG. 10 is a circuit diagram showing an example of a heater drive circuit provided in a recording head according to the fifth embodiment of the present invention.

FIG. 11 is a circuit diagram showing a conventional heater drive circuit.

FIG. 12 is a timing chart of a signal for operating a conventional heater drive circuit.

FIG. 13 is a diagram showing a wiring layout of a heat sink substrate. FIG. 14 is a circuit diagram showing a configuration of a conventional heater drive circuit.

FIG. 15 is an external perspective view illustrating the outline of the configuration of the inkjet recording apparatus according to the present embodiment.

FIG. 16 is a block diagram illustrating a functional configuration of the inkjet recording apparatus according to the present embodiment.

FIG. 17 is a schematic perspective view showing the configuration of the recording head according to the present embodiment. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The “heater substrate” used below does not indicate a simple substrate made of a silicon semiconductor, but a substrate provided with each element, wiring, and the like. Further, "on the heater substrate" means not only the surface of the heater substrate but also the surface of the element substrate and the inside of the element substrate near the surface. In addition, the term “built-in” according to the present embodiment is not a word indicating simply arranging each separate element on a substrate, but is a method for manufacturing each semiconductor element. It indicates that it is integrally formed and manufactured on a heat sink substrate by a process or the like.

[First embodiment]

FIG. 1 is a circuit diagram illustrating a configuration of a heater drive circuit provided on a heater substrate of an inkjet recording head according to a first embodiment of the present invention. In FIG. 1, ₁₀₁ ^ to _{101 lx} indicate heaters (heat resistances) for printing, and when each heater is energized to generate heat, ink droplets are emitted from each corresponding nozzle. Discharged. That is, in a recording head using this heater substrate, ejection ports (nozzles) for ejecting ink are provided corresponding to the respective heaters. Here, these heaters 101 ul to 101 _lx are divided into blocks 1 to m, and each block is provided with X heaters and corresponding heaters. X NMOS transistors are included. One 02 "to 102 _lx are each NMOS transistors for turning on Z off the power supply to the corresponding heater. 103 u~l 03 _lx is provided a constant current source, corresponding to each heater. These each of the constant current source 103 u~l 03 _lx, NMOS transistors 102 ^ ~丄02 _lx, respectively and heat Isseki group _{101 1:} ί ~101 are connected in series to each _1Kai, each current source 103u~ l 03 _1χ outputs a constant current to the connection terminal The magnitude of this constant current value is adjusted by a control signal from the reference current circuit 105. 104 is a control circuit, which corresponds to the recording data to be recorded. Controls on / off of each NMOS transistor 102. The reference current circuit 105 outputs a control signal ₁₁₀ to the constant current sources 103 „to 103 _1χ , and the constant current generated by each constant current source Controlling the value. 106 and 107 are power supply pads connected to a power supply unit (not shown) outside the substrate. Electric power for driving the heater is supplied through these power supply pads. Each of 108 and 109 is a power supply line for supplying electric power for driving the heater from each of the power supply pads 106 and 107 to the blocks 1 to m.

[Operation of heater drive circuit]

Fig. 2 is a diagram showing an equivalent circuit of a circuit including one heater, one NMOS transistor, and one constant current source. Fig. 3 shows the drive signal and the timing explaining the current flowing through each heater. This is a chart.

2, a signal VG is a recording signal corresponding to an image signal supplied from the control circuit 104 in FIG. Note that the configuration of the control circuit 104 may be a circuit that controls an image signal such as a shift register and a latch. The signal VC is a control signal supplied from the reference current circuit 105 to the constant current source 203, and corresponds to the control signal 110 in FIG. 1. According to the control signal VC, the constant current source 203 (the constant current in FIG. source 103 _{1] L} ~103 corresponding to _1Kai) by the emitted electrostatic current values are controlled. The power supply VH indicates a voltage source for driving the heater 201. Here, for simplicity, it is assumed that the NMOS transistor 202 ideally operates as a switch between the drain and source terminals. When the signal level of the signal VG is high, the NMOS transistor 202 turns on (short circuit between the drain and source). It is assumed that it is turned off at the mouth level (open between the drain and source). When a voltage between the terminals is applied to the constant current source 203, a constant current set by the control signal VC flows between the terminals (from the top to the bottom in the figure).

FIG. 3 is a diagram showing the generation timing of the signal VG and the waveform of the current flowing to the heater 201 at that time.

In FIG. 3, the signal VG is at a low level during a period up to a time tl. In this period, since the output of the constant current source 203 and the heater 201 are cut off, no current flows through the heater 201. Next, during the period from the time t1 to the time t2, the signal VG goes to the high level, the current flows between the source and the drain of the NMOS transistor 202, and the output current of the constant current source 203 becomes high. Flows to Then, after time t2, the signal VG becomes low level, and the power supply to the heater 201 is cut off.

The current supply time to the heater 201 is controlled by the pulse width of the signal VG, and the magnitude of the current Ih flowing through the heater 201 is controlled by the control signal VC of the constant current source 203. In the example of FIG. 3, the current flowing through the sun 201 is represented by numeration values I1 to I3 corresponding to the control signal VC.

As shown in FIG. 3, the constant current value I (11 to 13) determined by the control signal VC flows through the light source 201 during a period from time t1 to time t2 according to the pulse width of the signal VG. As a result, the ink existing in the nozzle (flow path) provided corresponding to the heater 201 is heated and foamed, and the ink is ejected from the nozzle corresponding to the heater, so that a predetermined pixel (dot) is formed. Recorded.

With the above configuration, current flows from the constant current source 203 by the reference current circuit 105. The determined constant current value is determined, and the determined current value flows through the heater 201 only while the NMOS transistor 202 driven by the signal VG is on.

In the above description, it is described that the source and the drain are short-circuited when the NMOS transistor 202 is on. However, when the NMOS transistor 202 is on, there is a resistance between the source and the drain. By setting the power supply voltage high enough for the voltage drop in this resistor, the output current of the constant current source is applied to the heater as it is, so that the same operation as the above description of driving the heater is performed. .

[Second embodiment]

FIG. 4 is a diagram showing an example in which the constant current source 103 of FIG. 1 of the first embodiment described above is constituted by NMOS transistors 401 n to 401 _lx . Portions common to FIG. Is omitted.

NMOS transistor 401 'to 401 drains of _lx are connected to the NMOS transistor 102 u~l 02 _lx each source for Suitchin grayed. NMOS transistor 401 U～401 _lx gates of the reference current circuit 105 are connected. Thus the control signal 110, the value of the current flowing through the respective heaters are more controlled NMOS transistor 401 u~401 _lx gate voltage by Ri controlled by a control signal 110 from the reference current circuit 105 .

Next, the operation of the NMOS transistors 401 u to 401 _lx in FIG. 4 will be described with reference to FIGS.

FIG. 5 is a diagram showing a typical static characteristic example of the NMOS transistor used for the NMOS transistors 401 n to 401 _lx , and FIG. 6 shows the bias conditions thereof.

FIG. 5 shows the characteristics of the drain current Id when the drain voltage Vds is changed with the gate voltage Vg being a parameter. Dray in Figure 5 The gate voltage Vg and the drain voltage Vds of the NMOS transistors 401 u to 401 _lx in FIG. 4 are set so as to operate in a region where the drain current Id does not change much with the change in the drain voltage Vds (saturation region, etc.). I do. As a result, it is possible to obtain an output current that does not largely depend on the drain voltages Vds of the NMOS transistors 401 _{1 to} 401 _lx . As described above, the NMOS transistors 401 η to _4011χ shown in FIG. 4 operate as a constant current source that _{supplies a} constant current to each heater. In addition, since the drain current Id changes according to the gate voltage Vg of the NMOS transistors 401 u to 401 _lx , control is performed so that the current value flowing to each heater through the gate voltage Vg is set to a desired current value. Can be. The on-resistance characteristic, which is the current-voltage characteristic between the source and drain of the NMOS transistors 401 u to 401 _lx , can be controlled by the gate voltage V g, that is, the control signal 110. By controlling this on-resistance value, A desired constant current can be supplied to each heater.

[Third embodiment]

FIG. 7 shows that the drains of the NMOS transistors 401 „to 401 _lx shown in FIG. 4 are further connected to the sources of the NMOS transistors 701 u to 701 _lx , and two NMOS transistors are cascaded in series to form a constant current source 203 ( 5 is a circuit diagram showing an example in which FIG. 2 is formed. In addition, parts common to FIGS. 1 and 4 described above are denoted by the same reference numerals, and description thereof will be omitted. The case of two stages will be described, but the present invention can of course be applied to a case of more stages.

Here, each gate of the NMOS transistors 701 u to 701 _lx is also connected to the reference current circuit 105. Here, the NMOS transistors 701 u to 701 _lx operate as gate-grounded transistors, and fix the drain voltage of the NMOS transistor AO ln O _lx by the potential between the gate and the source of the NMOS yo iu Yoi. Here, the reference current circuit 105 connects the NMOS transistors 401 n to 401 to the drain voltage V As to the region in behavior of the saturation region or the like with little change in the drain current Id with respect to a change in ds, the control signal 111, which sets the gate voltage of NMOS 701 u~701 _lx. The source voltage of the MOS transistors 701 u to 701 _lx can be suppressed to a small potential change between the gate and the source by fixing the gate voltage with respect to the voltage fluctuation of the drain of the NMOS transistors 701 u to 701 _lx. it can.

According to the circuit configuration of FIG. 7, the fluctuation of the power supply voltage NM the fluctuation of the on-resistance value and the wiring resistance value of the switching NMOS transistors 102 n to l 02 _lx compared to the circuit of FIG. Fluctuations in the drain voltage of the NMOS transistors 401 u to 401 _lx operating as a constant current source can be suppressed.

Figure 8 A is a diagram showing a current output characteristic example of the NMOS transistor 701 U～701 _lx and the NMOS transistor 401 u~401 1 circuit portion of _lx 7, FIG. 8B is a diagram illustrating the bias conditions.

FIG. 8A shows a case where a constant voltage is applied to the gate of the NMOS transistor 701 in FIG. 8B and the drain voltage of the NMOS transistor 701 is changed in parallel with the gate voltage of the NMOS transistor 401. It shows the output current value. In this case, the change in the output current with respect to the change in the drain voltage of the NMOS transistor 701 is smaller than that in FIG.

[Fourth embodiment]

FIG. 9 is a circuit diagram illustrating the circuit of FIG. 4 with a specific configuration example of the reference current circuit 105 added.

The reference current circuit 105 constitutes a current mirror circuit that outputs a current from the drains of the NMOS transistors 401 „to 401 _{lx based on} the NMOS transistor 901. The NMOS transistor 901 has a gate and a drain that are diode-connected. The reference current source 902 Is connected. The gate of the NMOS transistor 901 is commonly connected to the gate of the NMOS transistor 401: ^ to 01 _lx . When the gate size of the NMOS transient scan evening 901 and NMOS transistor 401 u~401 _lx are equal, a gate voltage of the NMOS transistor 901 and the NMOS transistor 40 1 u~401 _lx become equal, the reference current equal current by a reference current source 902 Output from the drains of the NMOS transistors 401 u to 401 _lx . If the gate sizes of NMOS transistor 901 and NMOS transistor 4011 _{: L to} 401 _lx are different, it is proportional to the reference current corresponding to the gate size ratio of NMOS transistor 901 and NMOS transistor 401 „to 401 _lx. A constant output current is obtained.

[Fifth embodiment]

FIG. 10 is a circuit diagram showing the circuit of FIG. 7 with a specific configuration example of the reference current circuit 105 added.

Here, the gates of the NMOS transistors 701 u to 701 _lx are connected to the gate of the NMOS transistor 1001 of the reference current circuit 105. NMO S transistor evening 1001, gate and drain are Daio one de connection, in which can grant a constant voltage to the NMOS transistor 701 "~701 _lx gate.

The configuration of FIG. 10, the NMOS transistor 1001 and NMOS Tran register 701 "~701 _lx gate first source voltage is substantially equal to this, the drain voltage of the NMOS transistor 901 and NMOS transistors 401 ~ 401 _lx be equal. The Thus, by making the gate voltage and drain voltage of the NMOS transistor 901 and the NMOS transistors 401 n to 401 _lx equal, the reference current from the reference current source 902 depends on the drain voltages of the NMOS transistors 701 u to 701 _lx. Instead, it is accurately mirrored by the output currents of the NMOS transistors 401 u to 401 _lx . As described above, according to this embodiment, a constant current source circuit for supplying a constant current to the heater and a switching circuit for controlling the current application time can be configured using the NMOS transistor.

It is also desirable to set the withstand voltage of the MOS transistor of this switching circuit higher than the withstand voltage of the MOS transistor of the constant current source circuit. Further, according to the present embodiment, a constant current can be supplied when the heater is driven, and the current value of the constant current can be adjusted and controlled. Thus, uniform energy can be applied to each heater.

Further, the circuit configurations of FIGS. 1, 4, 7, 9, 10 and the like in each of the above embodiments may be formed on one element substrate. Although the reference current circuit may be a circuit provided outside the element substrate, it is preferable that the reference current circuit is formed on the same element substrate.

Next, an example of an ink jet head having the above-described heater substrate and an ink jet recording apparatus equipped with the ink jet head will be described.

FIG. 15 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus 1 which is a typical embodiment of the present invention.

As shown in FIG. 15, an ink jet recording apparatus (hereinafter, referred to as a recording apparatus) is generated by a carriage motor M 1 on a carriage 2 equipped with a recording head 3 for performing recording by discharging ink according to an ink jet system. The driving force is transmitted from the transmission mechanism 4, the carriage 2 is reciprocated in the direction of arrow A, and, for example, a recording medium P such as recording paper is fed through the paper feeding mechanism 5 'and conveyed to the recording position. At the recording position, recording is performed by ejecting ink from the recording head 3 onto the recording medium P. In addition, in order to maintain the state of the recording head 3 in a good state, the carriage 2 is moved to the position of the recovery device 10, and the ejection recovery processing of the recording head 3 is performed intermittently.

In addition to mounting the recording head 3 on the carriage 2 of the recording device 1, The ink cartridge 6 for storing the ink to be supplied to the recording head 3 is installed. The ink cartridge 6 is detachable from the carriage 2. The recording device 1 shown in Fig. 15 is capable of color recording, so that the carriage 2 contains magenta (M), cyan (C), yellow (Y), and black (Κ) inks, respectively. It has four ink cartridges. Each of these four ink cartridges is independently removable.

The carriage 2 and the recording head 3 are designed so that the joint surfaces of the two members are properly contacted to achieve and maintain the required electrical connection. The recording head 3 performs recording by selectively discharging ink from a plurality of discharge ports by applying energy according to a recording signal. In particular, the recording head 3 of this embodiment employs an ink-jet method in which ink is ejected using thermal energy, has an electrothermal converter for generating thermal energy, and is applied to the electrothermal converter. The electrical energy is converted into thermal energy, and the thermal energy is applied to the ink. The ink is ejected from the ejection port using the pressure change caused by bubble growth and shrinkage caused by film boiling caused by applying the thermal energy to the ink. The electrothermal converter is provided corresponding to each of the discharge ports, and discharges ink from the corresponding discharge port by applying a pulse voltage to the corresponding electrothermal converter in accordance with a recording signal.

As shown in FIG. 15, the carriage 2 is connected to a part of the drive belt 7 of the transmission mechanism 4 for transmitting the drive force of the carriage motor Ml, and the arrow A along the guide shaft 13 The guide is slidably guided in the direction. Therefore, the carriage 2 reciprocates along the guide shaft 13 by the forward and reverse rotation of the carriage motor Ml. Further, a scale 8 is provided to indicate the absolute position of the carriage 2 along the movement direction of the carriage 2 (the direction of arrow A). In this embodiment, the scale 8 uses a black PET printed on a transparent PET film at a required pitch, one of which is fixed to the chassis 9 and the other is supported by a panel panel (not shown). Sa Have been.

Further, the printing apparatus 1 is provided with a platen (not shown) opposed to the discharge port surface on which the discharge port (not shown) of the recording head 3 is formed. At the same time as the carriage 2 on which the head 3 is mounted is reciprocated, a recording signal is applied to the recording head 3 to eject ink, thereby performing recording over the entire width of the recording medium P conveyed on the platen. Is

Further, in FIG. 15, reference numeral 14 denotes a conveying roller driven by the conveying motor M2 to convey the recording medium P, and reference numeral 15 denotes a recording medium P applied to the conveying roller 14 by a spring (not shown). A pinch roller 16 is in contact with the pinch roller 16, a pinch roller holder rotatably supporting the pinch roller 15, and 17 is a transport roller gear fixed to one end of the transport roller 14. Then, the transport roller 14 is driven by the rotation of the transport mode M2 transmitted to the transport roller gear 17 via an intermediate gear (not shown).

Further, reference numeral 20 denotes a discharge roller for discharging the recording medium (sheet) P on which an image has been formed by the recording head 3 to the outside of the recording apparatus, and the rotation of the conveyance mode M2 is transmitted. It is adapted to be driven. The discharge port L20 is brought into contact with a spur roller (not shown) which presses the recording medium P with a panel (not shown). 22 is a spur holder for rotatably supporting the spur roller.

Further, as shown in FIG. 15, the recording apparatus 1 has a desired position (outside the recording area) outside the range of the reciprocating movement (outside the recording area) for the recording operation of the carriage 2 on which the recording head 3 is mounted. For example, at a position corresponding to the home position), a recovery device 10 for recovering the ejection failure of the recording head 3 is provided. The recovery device 10 includes a capping mechanism 11 1 for capping the discharge port surface of the recording head 3 and a wiping mechanism 12 2 for cleaning the discharge port surface of the recording head 3. Capping of the discharge port surface by The ink is forcibly ejected from the ejection port by a suction means (suction pump or the like) in the recovery device in conjunction with the ink jetting, thereby increasing the viscosity of the ink or air bubbles in the ink flow path of the recording head 3. An ejection recovery process such as removal of the ink is performed. In addition, during non-printing operation or the like, the ejection opening surface of the recording head 3 is cabbed by the cabbing mechanism 11, thereby protecting the recording head 3 and preventing evaporation and drying of the ink. On the other hand, the wiping mechanism 12 is arranged in the vicinity of the capping mechanism 11 and wipes ink droplets adhered to the ejection opening surface of the recording head 3.

The capping mechanism 11 and the wiping mechanism 12 make it possible to keep the ink ejection state of the recording head 3 normal.

FIG. 16 is a block diagram showing a control configuration of the printing apparatus shown in FIG. As shown in FIG. 16, the controller 600 includes an MPU 601, a program corresponding to a control sequence described later, a ROM 602 storing required tables, and other fixed data, control of a carriage mode Ml, and control of a transfer mode M2. A special-purpose integrated circuit (AS IC) 603 for generating a control signal for controlling the recording head 3; a RAM 604 provided with an image data development area and a work area for executing a program; A system bus 605 that interconnects the AS IC 603 and RAM 604 to exchange data, inputs analog signals from the sensors described below, converts them to AZD, and supplies digital signals to the MPU 601 A / D It consists of a converter 606 and so on.

In FIG. 16, reference numeral 610 denotes a combination (or a reader for reading images, a digital camera, or the like) serving as a supply source of image data, and is generally called a host device. Image data, commands, status signals, and the like are transmitted and received between the host device 610 and the recording device 1 via the interface (IZF) 611. Reference numeral 62 denotes a group of switches. The power switch 621, the print switch 62 for instructing the start of printing, and the ink for the recording head 3 for maintaining good ink ejection performance. It consists of a switch for receiving command input from the operator, such as a recovery switch 623 for instructing the start of processing (recovery processing). 630 is composed of a position sensor 631 such as a photo hood for detecting the home position h, and a temperature sensor 632 provided at an appropriate place of the recording device for detecting the environmental temperature. This is a group of sensors for detecting the device status.

Further, 640 is a carriage motor driver for driving a carriage motor Ml for reciprocally scanning the carriage 2 in the direction of arrow A, and 640 is for driving a transport motor M2 for transporting the recording medium P. It is a transport motor driver.

The ASIC 603, when performing a print scan by the print head 3, directly accesses the storage area of the RAM 602 and drives the drive data (D ATA).

FIG. 17 is a schematic perspective view showing the configuration of a recording head cartridge including the recording head according to the present embodiment.

As shown in the figure, a recording head cartridge 1200 in this embodiment includes an ink tank 130 that stores ink and an ink supplied from the ink tank 130 according to recording information. The recording head 3 has a recording head 3 ejected from a nozzle, and the recording head 3 employs a so-called cartridge system which is removably mounted on the carriage 2. In recording, the recording head cartridge 1200 is reciprocally scanned along the carriage axis, and a color image is recorded on a recording sheet. In the recording head cartridge 1200 shown here, in order to enable high-quality color recording with photographic effects, ink tanks such as black, light cyan (C), light magenta (LM), Cyan, magenta and yellow Color independent ink tanks are provided, each of which is detachable from the recording head 3.

Note that the recording head cartridge 1200 here shows a form in which the ink tank 1300 can be attached to and detached from the recording head. However, the recording head cartridge integrated with the recording head is shown. It may be one cartridge.

Fig. 17 shows a case where six colors of ink are used.However, as shown in Fig. 15, printing is performed using four colors of ink, for example, black, cyan, magenta and yellow. May be. In this case, independent ink tanks for each of the four colors may be detachably attached to the recording head 3.

Further, in this embodiment, an example of a circuit using an NMOS transistor has been described, but the present invention is not limited to this, and it is needless to say that a PMOS transistor can be similarly realized.

Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), a device including one device (for example, a copying machine, a facsimile machine, etc.) May be applied.

In this embodiment, the case of the ink jet recording head has been described, but the present invention is not limited to this, and can be applied to, for example, a thermal head.

The present invention is not limited to the embodiments described above, and various changes and modifications can be considered. Therefore, the technical scope of the present invention is determined based on the following claims.

Claims

The scope of the claims

1. A recording head having a plurality of recording elements,

A plurality of switching circuits provided in association with each of the plurality of printing elements, for controlling energization of the corresponding printing elements;

A constant current source that is provided corresponding to each of the plurality of recording elements and that supplies a constant current to each of the recording elements;

A current control circuit for controlling the constant current supplied by the constant current source.

2. The recording head according to claim 1, wherein the constant current source includes a MOS transistor, and the constant current source controls the on-resistance of the MOS transistor of the constant current source. Outputs constant current.

3. The recording head according to claim 2, wherein the current control circuit operates such that the M〇 transistor of the constant current source operates in a saturation region where a change in drain current is small with respect to a change in drain voltage. And controlling the gate voltage of the MOS transistor of the constant current source.

4. The recording head according to claim 2, wherein the constant current source connects a source of a second MOS transistor in series with a drain of the first MOS transistor, and the current control circuit comprises: The gate voltages of the first and second MOS transistors are controlled such that the first and second MQS transistors operate in a saturation region where a change in drain current is small with respect to a change in drain voltage.

5. The recording head according to claim 2, wherein the current control circuit has a constant current circuit and a MOS transistor, and outputs an output of the constant current circuit to a base of the MOS transistor of the current control circuit. And the MOS transistor of the constant current source Connected to the base of the star.

6. The recording head according to claim 5, wherein the current control circuit and the constant current circuit constitute a power mirror circuit.

7. The recording head according to claim 4, wherein the current control circuit includes a constant current circuit and two MOS transistors, and a base of each of the two MOS transistors is the first MOS transistor. And the base of the second MOS transistor.

8. The recording head according to claim 2, wherein a withstand voltage of the MOS transistor of the constant current source is higher than a withstand voltage of the MOS transistor of the switching circuit.

9. The recording head according to claim 1, wherein the plurality of recording elements, the plurality of switching circuits, the constant current source, and the current control circuit are formed on the same element substrate.

1 0. The recording device,

Conveying means for relatively moving a recording head having a plurality of recording elements and a recording medium,

Drive control means for driving the recording head in accordance with an image signal to form an image on the recording medium in synchronization with the relative movement by the transport means; and

A plurality of switching circuits provided in association with each of the plurality of printing elements, for controlling energization of the corresponding printing elements,

A constant current is provided for each of the plurality of printing elements and provided for each of the plurality of printing elements. A constant current circuit for flowing

A current control circuit for controlling the constant current supplied from the constant current circuit.

11. The recording apparatus according to claim 10, wherein the constant current circuit includes a MOS transistor, and the constant current circuit controls an ON resistance of the MOS transistor of the constant current circuit. Output the constant current.

1 2. A recording head cartridge having a plurality of recording elements,

A plurality of switching circuits that are provided in association with each of the plurality of recording elements and control energization of the corresponding recording elements; and a plurality of switching circuits that are provided in correspondence with each of the plurality of recording elements. A recording head having a constant current source for flowing a constant current, and a current control circuit for controlling the constant current supplied by the constant current source;

An ink tank for holding ink supplied to the head.