JP4261874B2 - Recording head and recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording head, and more particularly to a recording head that can equalize the amount of energy consumed by a plurality of recording elements connected to a common power source.
[0002]
[Prior art]
For example, as an information output device in a word processor, personal computer, facsimile, or the like, there is a printer that records information such as desired characters and images on a sheet-like recording medium such as paper or film.
[0003]
Various types of recording methods are known for printers, but inkjet methods have recently been used for reasons such as non-contact recording on recording media such as paper, easy colorization, and high quietness. In particular, the configuration is a serial in which a recording head for ejecting ink according to desired recording information is mounted and recording is performed while reciprocating scanning in a direction crossing the feeding direction of a recording medium such as paper. In general, the recording method is widely used because it is inexpensive and easy to downsize.
[0004]
Among the inkjet methods, the bubble jet (registered trademark) recording method (BJ method) is a method in which ink is rapidly heated and vaporized by a heating element (heater), and ink droplets are ejected from the orifice by the pressure of the generated bubbles. is there.
[0005]
FIG. 4 is a circuit diagram showing an example of a heater drive circuit inside a recording head of an ink jet printer that performs recording by the bubble jet (registered trademark) recording method.
[0006]
A heater element R1 formed on the element substrate of the recording head and a switching element Q1 for switching current to the heater element are connected in series between the power source VH and the ground, and according to recording information from the printer main body. In response to the control signal, an arbitrary switching element is turned on or off, and ink is ejected from the nozzle corresponding to the driven heater element to form an image.
[0007]
In a printer having a recording head that ejects ink using the heat energy generated from such a heater element, in order to obtain a high-quality image, the volume of ejected ink droplets must always be constant and stable. is necessary. For this purpose, it is desirable to keep the heating value of the heater constant.
[0008]
Here, the calorific value P at the heater that converts electrical energy into thermal energy is:
V: potential difference at the heater R: resistance value of the heater t: voltage application time
P = (V ² / R) t (1)
It is represented by
[0009]
As can be seen from equation (1), the amount of heat generated by the heater varies greatly depending on the resistance value of the heater and the voltage applied to the heater. Of these, the heater resistance varies by about 20% due to the heater manufacturing process. As a method for suppressing the influence of the variation on the heat generation amount, methods described in JP-A-7-76077 (Patent Document 1) and JP-A-10-95116 (Patent Document 2) are known.
[0010]
The present invention has been made in view of the above situation, and an analog circuit excluding a voltage for driving a digital circuit and a power supply voltage applied to a recording element (an analog circuit for obtaining information such as temperature). in the case where the voltage for driving the like) are different, use an ink jet recording head and said ink jet recording head capable of possible to simplify the overall structure by supplying only the voltage for driving the digital circuit from the outside It is an object of the present invention to provide a recording apparatus.
[0011]
In the method described in Patent Document 2, the on-resistance of a switching element such as a MOS transistor directly connected to the heater also has manufacturing variations. Since the on-resistance of the MOS transistor is inserted in series with the resistance of the heater between the power supply and the ground, the voltage applied to the heater is divided by the ratio of the resistance of the heater and the on-resistance of the MOS transistor. It becomes a pressed voltage.
[0012]
For this reason, the variation in the on-resistance of the MOS transistor is equivalent to the change of the V term in the equation (1), and affects the amount of heat generated by the heater. In order to suppress this effect, a dummy MOS transistor is formed in the recording head, the on-resistance of the MOS transistor is measured, and the voltage V applied to the heater is calculated, as in the method of the patent document. Is used to adjust the pulse width of the pulse signal applied to the heater so that the amount of heat generated by the heater is constant.
[0013]
In addition to the above factors that affect the amount of heat generated by the heater, there are the following factors.
[0014]
Variation or voltage fluctuation in the initial state of the power supply voltage for supplying power to the heater directly leads to fluctuation in voltage applied to the heater. In addition, since the resistance component existing in the wiring connected to the heater and the connector that connects the recording head to the printer main body is connected in series between the heater resistance and the power source, a voltage drop occurs due to this resistance, and as a result, the heater The voltage applied to is changed.
[0015]
Further, the on-resistance of the MOS transistor calculated by the above method and the on-resistance of the actually driven MOS transistor are not always equal, and change depending on a temperature change or a gate drive voltage.
[0016]
As means for solving these fluctuation factors, a method described in Japanese Patent Laid-Open No. 2001-277516 (Patent Document 3) will be described with reference to FIG.
[0017]
As shown in the figure, each recording element is applied to a heater R1 that generates thermal energy for ejecting ink, a switching element Q1 such as a MOS transistor for applying a current to the heater R1, and a gate of Q1. A bit selection logic 102 for controlling the voltage and a voltage control circuit 101 for supplying power to the bit selection logic 102 are provided.
[0018]
In the voltage control circuit 101, R2 is a resistor manufactured from the same material as R1, and Q2 is a MOS transistor of the same type as Q1. That is, R2 and Q2 are manufactured in the same manufacturing process so as to have the same characteristics as R1 and Q1, which are the heater and MOS for discharging ink, respectively. VR1 is a constant voltage source based on VH, and the operational amplifier OP1 adjusts the gate of Q2 so that the potential difference between the terminals of the heater resistor R2 is equal to the voltage of VR1 . As a result, the potential difference between the terminals of the heater resistor R1 and the voltage of VR1 are adjusted to be equal. Here, R2, Q2, VR1 , and OP1 constitute a constant voltage feedback circuit, and this output is supplied to the bit control logic 102 as a power source.
[0019]
The operation will be described. When “0” is inputted to the input, the MOS transistor Q1 is turned on, a current flows through the heater R1, and ink is ejected from the nozzle. The voltage applied to the gate of Q1 at this time is substantially equal to the power supply voltage of the bit control logic 102, and this power supply voltage is supplied by the voltage control circuit 101. As described above, since R2 and Q2 have the same characteristics as R1 and Q1, respectively, the ratio between the resistance value of R1 and the on-resistance value of Q1 and the ratio of the resistance value of R2 and the on-resistance value of Q2 are equal. Is considered. The inverting input of the operational amplifier OP1 is connected to one end of R2 and the source of Q2, and the constant voltage source VR1 based on VH is connected to the non-inverting input of the operational amplifier OP1. Since the gate of Q2 is connected to the output of OP1, feedback is applied to the gate voltage of Q2 so that the potential difference between the R2 terminals is always VR1 by OP1.
[0020]
Since the output of OP1 is a power source for the bit control logic 102, the output voltage of OP1, that is, the same voltage as the gate voltage of Q2 is applied to the gate of Q1 when the heater resistor R1 is driven. Since the gate voltages of Q1 and Q2 are equal, the ratio of the on-resistance values of R1 and Q1 is equal to the ratio of the on-resistance values of R2 and Q2, and the potential difference between the terminals of R1 is equal to VR1 .
[0021]
If the potential difference between the terminals of the heater resistor R1 is constant at VR1 , and the resistance value of the heater resistor R1 can be measured in advance using a dummy resistor or the like, the heat generation amount P at the heater resistor R1 is
P = ( VR1 ² / R1) t (2)
Therefore, the amount of heat generated by the heater resistor R1 can be made constant by controlling the pulse width t according to the resistance value of the heater resistor R1.
[0022]
[Patent Document 1]
JP 7-76077 A [Patent Document 2]
JP-A-10-95116 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-277516 [0023]
[Problems to be solved by the invention]
In the above-described conventional example, the heater resistance value varies by ± several tens of percent between the individual heads, so that the pulse width is controlled to keep the amount of heat generated by the heater constant.
[0024]
That is, assuming that the voltage applied to the heater is constant and the resistance value of the heater has a variation of ± 20%, the pulse width can be varied by ± 20% in order to keep the amount of heat generated in the heater constant. Necessary.
[0025]
In order to perform high-speed recording, it is desirable to drive all the heaters at the same time, but in actuality, the maximum current that can be flown is limited due to the power supply capacity and voltage drop in the wiring. Since it cannot be driven, a plurality of heaters are divided into several blocks, and the current flowing at a time is suppressed by time-division driving in units of blocks.
[0026]
For this reason, in order to perform high-speed recording, it is necessary to shorten the pulse width applied to the heater and increase the number of blocks to be driven within a unit time, but when performing control to vary the pulse width as described above, There arises a problem that the drive frequency cannot be increased so much in order to secure the fluctuation range of the pulse.
[0027]
The present invention has been made in view of the situation as described above. Regardless of variations in the resistance value of the recording element, the resistance value of the power supply wiring, etc., each pulse width applied to each recording element is not changed. It is an object of the present invention to provide a recording head capable of equalizing the amount of energy consumed by a recording element and a recording apparatus including the recording head.
[0028]
In order to achieve the above object, a recording head as one aspect of the present invention is a recording head having a plurality of recording elements connected to a common power source,
A switching element that is provided corresponding to each recording element and that controls driving of the recording element by a voltage applied to a control terminal;
A reference voltage generating circuit for generating a reference voltage from the power source;
A voltage control circuit that controls the potential difference between the terminals of the recording element to be equal to the reference voltage when the recording element is driven;
The recording element is:
A thermal energy converter for generating thermal energy to be applied to ink in order to eject ink using thermal energy,
The reference voltage generation circuit includes:
A first dummy recording element having the same characteristics as the recording element;
A resistance value detection circuit for detecting a resistance value of the first dummy recording element;
A square root circuit for obtaining a square root of the detected resistance value;
A voltage conversion circuit that converts the value of the square root into a voltage and outputs a reference voltage,
The voltage control circuit includes:
A second dummy recording element connected in parallel with the recording element and having the same characteristics as the recording element;
A dummy switching element connected in series to the second dummy recording element and having the same characteristics as the switching element;
A detection element that feeds back a detection output to a control terminal of the dummy switching element so that a potential difference between the terminals of the second dummy recording element is equal to a voltage of the reference voltage output from the reference voltage generation circuit; Including the circuit,
The detection output is connected to the control terminal of the switching element, and includes a logic circuit provided corresponding to the recording element to which a selection signal indicating whether to drive the recording element is input,
The value of the reference voltage from the reference voltage generation circuit is proportional to the square root of the resistance value of the first dummy recording element, and the detection output from the voltage control circuit is used as a power source for the logic circuit. Features.
[0029]
That is, in a recording head having a plurality of recording elements connected to a common power source, a switching element for controlling the driving of the recording element with a voltage applied to the control terminal corresponding to each recording element is provided, and the reference voltage is supplied from the power source. And a voltage control circuit for controlling the potential difference between the terminals of the recording element to be equal to the reference voltage when the recording element is driven, and the value of the reference voltage is It is set to be proportional to the square root of the resistance value of the recording element.
[0030]
In this way, the amount of energy consumed by each recording element is made equal without changing the pulse width applied to each recording element, regardless of variations in the resistance value of the recording element and the resistance value of the power supply wiring. Can do.
[0031]
Therefore, when such a recording head is used, high-definition and high-quality recording can be performed at a higher speed.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[0033]
In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and graphics, but also for human beings, regardless of whether it is significant or not. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern or the like is widely formed on a recording medium or the medium is processed.
[0034]
“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.
[0035]
Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).
[0036]
First, a typical overall configuration and control configuration of a recording apparatus using the recording head of the present invention described below will be described.
[0037]
<Outline of the main unit>
FIG. 5 is an external perspective view showing an outline of the configuration of an inkjet printer IJRA which is a typical embodiment of the present invention. In FIG. 5, the carriage HC engaged with the spiral groove 5004 of the lead screw 5005 that rotates via the driving force transmission gears 5009 to 5011 in conjunction with the forward / reverse rotation of the drive motor 5013 has a pin (not shown). It is supported by the guide rail 5003 and reciprocates in the directions of arrows a and b. On the carriage HC, an integrated ink jet cartridge IJC incorporating a recording head IJH and an ink tank IT is mounted.
[0038]
Reference numeral 5002 denotes a paper pressing plate that presses the recording paper P against the platen 5000 in the moving direction of the carriage HC. Reference numerals 5007 and 5008 denote photo-couplers which are home position detectors for confirming the presence of the carriage lever 5006 in this region and switching the rotation direction of the motor 5013.
[0039]
Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head IJH. Reference numeral 5015 denotes a suction unit that sucks the inside of the cap, and performs suction recovery of the recording head through the cap opening 5023. Reference numeral 5017 denotes a cleaning blade, and reference numeral 5019 denotes a member that enables the blade to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, the blade is not in this form, and a known cleaning blade can be applied to this example.
[0040]
Reference numeral 5021 denotes a lever for starting suction for suction recovery, which moves in accordance with the movement of the cam 5020 engaged with the carriage, and the driving force from the driving motor is controlled by a known transmission mechanism such as clutch switching. Is done.
[0041]
These capping, cleaning, and suction recovery are configured so that desired processing can be performed at their corresponding positions by the action of the lead screw 5005 when the carriage comes to the home position side region. As long as the above operation is performed, any of these can be applied to this example.
[0042]
<Description of control configuration>
Next, a control configuration for executing the recording control of the above-described apparatus will be described.
[0043]
FIG. 6 is a block diagram showing the configuration of the control circuit of the inkjet printer IJRA. In the figure showing a control circuit, 1700 is an interface for inputting a recording signal, 1701 is an MPU, 1702 is a ROM for storing a control program executed by the MPU 1701, 1703 is various data (the recording signal and recording data supplied to the head). Etc.). Reference numeral 1704 denotes a gate array (GA) that controls supply of print data to the print head IJH, and also controls data transfer among the interface 1700, MPU 1701, and RAM 1703. Reference numeral 1710 denotes a carrier motor for conveying the recording head IJH, and 1709 denotes a conveyance motor for conveying the recording paper. Reference numeral 1705 denotes a head driver for driving the recording head, and reference numerals 1706 and 1707 denote motor drivers for driving the transport motor 1709 and the carrier motor 1710, respectively.
[0044]
The operation of the control configuration will be described. When a recording signal enters the interface 1700, the recording signal is converted into recording data for printing between the gate array 1704 and the MPU 1701. The motor drivers 1706 and 1707 are driven, and the recording head is driven according to the recording data sent to the head driver 1705 to perform recording.
[0045]
Here, the control program executed by the MPU 1701 is stored in the ROM 1702. However, an additional erasable / writeable storage medium such as an EEPROM is added, and the control program is changed from the host computer connected to the inkjet printer IJRA. It can also be configured to be able to.
[0046]
As described above, the ink tank IT and the recording head IJH may be integrally formed to constitute a replaceable ink cartridge IJC. However, the ink tank IT and the recording head IJH can be separated from each other. Then, only the ink tank IT may be exchanged when the ink runs out.
[0047]
FIG. 7 is an external perspective view showing the configuration of the ink cartridge IJC in which the ink tank and the head can be separated. As shown in FIG. 7, the ink cartridge IJC can separate the ink tank IT and the recording head IJH at the position of the boundary line K. When the ink cartridge IJC is mounted on the carriage HC, an electrode (not shown) for receiving an electric signal supplied from the carriage HC side is provided. By this electric signal, the recording head IJH as described above is provided. Is driven to eject ink.
[0048]
In FIG. 7, reference numeral 500 denotes an ink discharge port array. The ink tank IT is provided with a fibrous or porous ink absorber to hold ink.
[0049]
[Embodiment of recording head]
Hereinafter, an embodiment of a recording head of the present invention mounted on the above-described ink jet printer will be described.
[0050]
FIG. 1 is a circuit diagram showing a configuration of a drive control circuit of an embodiment of a recording head of the present invention.
[0051]
As shown in the figure, the drive control circuit of this embodiment includes a heater resistor R1 that generates thermal energy for ejecting ink and a switching element Q1 such as an N-type MOS transistor for applying a current to the heater resistor R1. A bit selection logic 102 for controlling the voltage applied to the gate of Q1 and a voltage control circuit 101 for supplying power to the bit selection logic 102 are provided for each printing element.
[0052]
In the voltage control circuit 101, R2 is a resistor manufactured from the same material as R1, and Q2 is a MOS transistor of the same type as Q1. That is, R2 and Q2 are manufactured in the same manufacturing process so as to have the same characteristics as R1 and Q1 which are heater resistors and MOS transistors for discharging ink.
[0053]
Vr1 is the output voltage of the reference voltage generation circuit 103, and the operational amplifier OP1 adjusts the gate of Q2 so that the potential difference between the terminals of the resistor R2 is equal to the voltage of Vr1. As a result, the potential difference between the terminals of the heater resistor R1 and the voltage of Vr1 are adjusted to be equal. Here, R2, Q2, Vr1, and OP1 constitute a constant voltage feedback circuit, and this output is supplied to the bit control logic 102 as a power source.
[0054]
Hereinafter, the operation of the drive control circuit of FIG. 1 will be described.
[0055]
A signal indicating “0” or “1” is input to the input of the bit control logic 102 from the printer body according to the information to be recorded. In the case of the circuit of FIG. 1, when “0” is input to the input, the MOS transistor Q1 is turned on, a current flows through the heater resistor R1, and ink is ejected from the nozzle.
[0056]
At this time, the voltage applied to the gate of Q1 is equal to the power supply voltage of the bit selection logic 102, and this power supply voltage is supplied by the voltage control circuit 101. As described above, since R2 and Q2 have the same characteristics as R1 and Q1, respectively, the ratio between the resistance value of R1 and the on-resistance value of Q1 and the ratio of the resistance value of R2 and the on-resistance value of Q2 are equal. Is considered. The inverting input of the operational amplifier OP1 is connected to one end of R2 and the source of Q2, and the reference voltage Vr1 is connected to the non-inverting input of the operational amplifier OP1. Since the gate of Q2 is connected to the output of OP1, the gate voltage of Q2 is fed back by OP1 so that the potential difference between the terminals of R2 is always Vr1.
[0057]
Since the output of OP1 serves as a power source for the bit control logic 102, the output voltage of OP1, that is, the same voltage as the gate voltage of Q2 is applied to the gate of Q1 when the heater R1 is driven. Since the gate voltages of Q1 and Q2 are equal, the ratio of the on-resistance value of R1 and Q1 is equal to the ratio of the on-resistance value of R2 and Q2, and the potential difference between the terminals of R1 is equal to Vr1.
[0058]
FIG. 2 is a block diagram of the reference voltage generation circuit 103 that generates the reference voltage Vr1 in FIG.
[0059]
Rr is a resistor made of the same material as R1, a resistance value detection circuit 201 for detecting the resistance value, a square root circuit 202 for obtaining the square root of the resistance value, and a voltage conversion circuit 203 for converting the output into a voltage. Composed. The configuration of each circuit 201 to 203 is not described in detail, but any known configuration may be used as long as it satisfies the above functions and can be formed on the same substrate (base) as other circuits.
[0060]
The output voltage Vr1 of the reference voltage generation circuit 103 is a voltage proportional to the square root of the resistance value of the resistor Rr. Since Rr is a resistor made of the same material as R1, and its resistance value is proportional, the output voltage Vr1 of the reference voltage generation circuit 103 is
Vr1 = √ (kR1) (3)
It becomes. Here, k is a constant.
[0061]
The amount of heat P generated by the heater R1 is t, where the pulse width applied to the heater is t.
P = (Vr1 ² / R1) t (4)
And substituting equation (3) into this equation,
P = [√ (kR1) ² / R1] t
It becomes. Therefore,
P = kt (5)
It becomes.
[0062]
Since k is a constant from equation (5), the amount of heat generated by the heater can be made constant by fixing the pulse width t regardless of the resistance value of the heater.
[0063]
As described above, according to the present embodiment, the pulse width applied to each heater is driven to be constant regardless of variations in the resistance value of each heater and the resistance value of the power supply wiring. The calorific value can be made equal.
[0064]
[Other Embodiments]
In the embodiment described above, an ink jet recording head of a so-called bubble jet (registered trademark) system in which ink is rapidly heated and vaporized by a heating element (heater) and ink droplets are ejected from an orifice by the pressure of the generated bubbles. Although described as an example, in view of the operation and effect of the present invention that suppresses the influence of power supply voltage fluctuation and parasitic resistance related to connection, the present invention is also applied to a recording head that performs recording by other methods. Obviously we can do it.
[0065]
In this case, instead of the heater resistance in each of the above embodiments, elements used in each method are provided.
[0066]
Furthermore, it goes without saying that a recording apparatus equipped with the recording head according to the present invention is also included in the present invention.
[0067]
In the above embodiment, the liquid droplets ejected from the recording head have been described as ink, and the liquid stored in the ink tank has been described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.
[0068]
The above embodiment includes means (for example, an electrothermal converter, a laser beam, etc.) that generates thermal energy as energy used for performing ink discharge, particularly in the ink jet recording system, and the ink is generated by the thermal energy. By using a system that causes a change in the state of recording, it is possible to achieve higher recording density and higher definition.
[0069]
As its typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recording information and applying a rapid temperature rise exceeding the film boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface of the liquid, and as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. When the drive signal is pulse-shaped, the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve the discharge of liquid (ink) with particularly excellent responsiveness.
[0070]
As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.
[0071]
As the configuration of the recording head, in addition to the combination configuration (straight liquid flow path or right-angle liquid flow path) of the discharge port, the liquid path, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting surface The configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, are also included in the present invention. In addition, Japanese Patent Application Laid-Open No. 59-123670, which discloses a configuration in which a common slot is used as a discharge portion of an electrothermal transducer, or an opening that absorbs a pressure wave of thermal energy is discharged to a plurality of electrothermal transducers. A configuration based on Japanese Patent Laid-Open No. 59-138461 disclosing a configuration corresponding to each part may be adopted.
[0072]
Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is satisfied by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration or a configuration as a single recording head formed integrally may be used.
[0073]
In addition to the cartridge-type recording head in which the ink tank is integrally provided in the recording head itself described in the above embodiment, it can be electrically connected to the apparatus body by being attached to the apparatus body. A replaceable chip type recording head that can supply ink from the apparatus main body may be used.
[0074]
In addition, it is preferable to add recovery means, preliminary means, and the like for the recording head to the configuration of the recording apparatus described above because the recording operation can be further stabilized. Specific examples thereof include a capping unit for the recording head, a cleaning unit, a pressurizing or sucking unit, an electrothermal converter, a heating element different from this, or a preheating unit using a combination thereof. In addition, it is effective to provide a preliminary ejection mode for performing ejection different from recording in order to perform stable recording.
[0075]
Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrated or may be a combination of a plurality of colors. An apparatus having at least one of full colors can also be provided.
[0076]
<Embodiment>
Examples of the embodiment of the present invention include the following.
[0077]
(Embodiment 1)
A recording head having a plurality of recording elements connected to a common power source,
A switching element that is provided corresponding to each recording element and that controls driving of the recording element by a voltage applied to a control terminal;
A reference voltage generating circuit for generating a reference voltage from the power source;
A voltage control circuit that controls the potential difference between the terminals of the recording element to be equal to the reference voltage when the recording element is driven;
The recording head, wherein the value of the reference voltage is proportional to the square root of the resistance value of the recording element.
[0078]
(Embodiment 2)
The reference voltage generation circuit includes:
A first dummy recording element having the same characteristics as the recording element;
A resistance value detection circuit for detecting a resistance value of the first dummy recording element;
A square root circuit for obtaining a square root of the detected resistance value;
A recording head according to claim 1, further comprising a voltage conversion circuit that converts the square root value into a voltage and outputs the voltage.
[0079]
(Embodiment 3)
The voltage control circuit includes:
A second dummy recording element connected in parallel with the recording element and having the same characteristics as the recording element;
A dummy switching element connected in series to the second dummy recording element and having the same characteristics as the switching element;
And a detection element that feeds back a detection output to a control terminal of the dummy switching element so that a potential difference between the terminals of the second dummy recording element is equal to a voltage of the reference voltage. 2 recording heads.
[0080]
(Embodiment 4)
The detection output is connected to the control terminal of the switching element and used as a power source of a logic circuit to which a selection signal indicating whether or not to drive the recording element is input. Recording head.
[0081]
(Embodiment 5)
5. The recording head according to any one of embodiments 1 to 4, wherein the switching element is a MOS transistor.
[0082]
(Embodiment 6)
The recording head according to any one of Embodiments 1 to 5, wherein recording is performed by discharging ink from each recording element.
[0083]
(Embodiment 7)
The recording head according to Embodiment 6, wherein each recording element is provided with a thermal energy converter for generating thermal energy applied to the ink so as to eject the ink using thermal energy.
[0084]
(Embodiment 8)
A recording apparatus that performs recording by any one of the recording heads according to any one of Embodiments 1 to 7.
[0085]
【The invention's effect】
As described above, according to the present invention, the recording element is consumed by each recording element without changing the pulse width applied to each recording element, regardless of variations in the resistance value of the recording element and the resistance value of the power supply wiring. The amount of energy can be made equal.
[0086]
Therefore, when such a recording head is used, high-definition and high-quality recording can be performed at a higher speed.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of a drive control circuit for a printhead according to an embodiment of the present invention.
FIG. 2 is a block diagram of the reference voltage generation circuit of FIG.
FIG. 3 is a circuit diagram of a conventional drive control circuit for a recording head.
FIG. 4 is a circuit diagram of a conventional drive control circuit for a recording head.
FIG. 5 is an external perspective view showing an outline of the configuration of an ink jet printer that is a typical embodiment of the present invention.
6 is a block diagram showing a configuration of a control circuit of the ink jet printer of FIG. 5. FIG.
FIG. 7 is an external perspective view illustrating a configuration of an ink cartridge in which an ink tank and a head can be separated.
[Explanation of symbols]
101 voltage control circuit 102 bit selection logic 103 reference voltage generation circuit OP1 operational amplifier Q1, Q2 MOS transistors R1, R2, Rr heater resistance Vr1 reference voltage

Claims (4)

A recording head having a plurality of recording elements connected to a common power source,
A switching element that is provided corresponding to each recording element and that controls driving of the recording element by a voltage applied to a control terminal;
A reference voltage generating circuit for generating a reference voltage from the power source;
A voltage control circuit that controls the potential difference between the terminals of the recording element to be equal to the reference voltage when the recording element is driven;
The recording element is:
A thermal energy converter for generating thermal energy to be applied to ink in order to eject ink using thermal energy,
The reference voltage generation circuit includes:
A first dummy recording element having the same characteristics as the recording element;
A resistance value detection circuit for detecting a resistance value of the first dummy recording element;
A square root circuit for obtaining a square root of the detected resistance value;
A voltage conversion circuit that converts the value of the square root into a voltage and outputs a reference voltage,
The voltage control circuit includes:
A second dummy recording element connected in parallel with the recording element and having the same characteristics as the recording element;
A dummy switching element connected in series to the second dummy recording element and having the same characteristics as the switching element;
A detection element that feeds back a detection output to a control terminal of the dummy switching element so that a potential difference between the terminals of the second dummy recording element is equal to a voltage of the reference voltage output from the reference voltage generation circuit; Including the circuit,
The detection output is connected to the control terminal of the switching element, and includes a logic circuit provided corresponding to the recording element to which a selection signal indicating whether to drive the recording element is input,
The value of the reference voltage from the reference voltage generation circuit is proportional to the square root of the resistance value of the first dummy recording element, and the detection output from the voltage control circuit is used as a power source for the logic circuit. Characteristic recording head. The recording head according to claim 1, wherein the switching element is a MOS transistor. Recording head according to claim 1 or 2, characterized in that for recording by discharging ink from the respective recording elements. Recording device and performing recording by the recording head according to claim 1, any one of 3.

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