JPH03208654A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To eliminate a need to adjust driving voltage of a recording head by providing a dummy resistance which is produced in the same process in which an electrothermal converter is produced in the manufacturing process of a recording head and which is constituted as an electrothermal converter having no relation to the delivery of ink. CONSTITUTION:A dummy resistance 33 is a heating resistor which has no relation to the delivery of ink and is produced in the same process in which a heating resister 11 is produced in the process of manufacturing a head unit, whereby the resistance of the dummy resistance 33 can be regarded as a resistance of the resistor 11. A constant-current power source 32 always feeds constant current to the resistance 33, whereby the terminal voltage based on the resistance inherent n the dummy resistance is amplified by an amplifier 34 and fed to a CPU 20 via an A/D converter 31. The CPU 20 adds predetermined correction value to the voltage information given thereto and outputs it as head voltage information to a power circuit 26 through a D/A converter 30 in such a manner that the voltage information from the D/A converter 30 is connected to adjust a reference voltage V0 in the circuit 26.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an inkjet recording device.

[Prior Art] Inkjet recording apparatuses are used as recording apparatuses such as printers and facsimile machines, and one type of inkjet recording apparatus is known to be equipped with a bubble jet type recording head.

In this type of inkjet recording device, an electrothermal energy converter such as a heating resistor is installed in the ink nozzle of the recording head, and the ink expands in the nozzle by applying an electric pulse to the electrothermal energy converter based on the recorded data. This generates bubbles that form flying ink droplets. The ink droplets adhere to the recording medium, and a predetermined image is recorded.

In this type of inkjet recording device, the growth of bubbles or the amount and speed of ink ejection changes depending on the voltage of the applied electric pulse, etc., and the diameter of the recorded dot changes. Also, depending on the magnitude of the voltage, ink ejection failure may occur. This may occur. Therefore, in order to ensure stable ink ejection and printing quality, it is necessary to apply an appropriate head drive voltage.

On the other hand, head drive voltages may differ from print head to print head due to variations in nozzle processing or the like.

On the other hand, in conventional inkjet printing apparatuses, the head drive voltage is adjusted by the power supply circuit, so the drive voltage must be adjusted for each printhead each time the printhead is assembled or replaced. There has been a problem in that voltage adjustment services and maintenance require a great deal of effort.

Particularly, voltage adjustment is extremely complicated in devices equipped with a large number of recording heads, such as those for color recording.

Furthermore, there is a possibility that an excessive voltage may be applied due to erroneous adjustment due to complications or the like, and the recording head may be damaged.

In order to deal with the above problems, for example, a patent application filed in 1986-
As shown in No. 219674, in order to set the drive voltage unique to the printhead, binary data consisting of ON/OFF combinations of dip switches etc. is preset to each printhead, and the printhead It has been proposed that the power supply section of the printing apparatus supplies a driving voltage specific to the printing head based on binary data when the printing head is installed in the printing apparatus.

In addition, as shown in Japanese Patent Application No. 60-219673,
A part of the adjustment resistor for adjusting the drive voltage specific to the recording head is provided on each recording head unit side as a head drive voltage adjustment resistor, and when the recording head is attached to the recording apparatus, the power supply section of the recording apparatus A system has also been proposed in which the drive voltage of the recording head is adjusted and output based on the value of a resistor attached to the recording head.

[Problems to be Solved by the Invention] However, in the above conventional example, when manufacturing a recording head, a head drive voltage specific to the head is measured, and binary data corresponding to the measured head drive voltage is set, or It is necessary to attach an adjustment resistor to the recording head.

Therefore, since the above-mentioned operations are required for each recording head to be manufactured, there are problems in that the mass production effect is impaired and the cost of the recording head becomes relatively high.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to improve the work for adjusting the recording head drive voltage, and furthermore, the work related to adjusting the head drive voltage when manufacturing the recording head. An object of the present invention is to provide an inkjet recording device equipped with a relatively inexpensive recording head that does not require the following.

[Means for Solving the Problems] To this end, the present invention provides a recording head that ejects ink by heating with an electrothermal transducer, and a recording head that is manufactured in the same way as the electrothermal transducer and is involved in ink ejection in the manufacturing process of the recording head. a dummy resistor configured as an electrothermal transducer, a resistance detection means for detecting a value applied to the resistance value of the dummy resistor, and a drive that determines a voltage to be applied to the electrothermal transducer based on the value detected by the resistance detection means. It is characterized by comprising voltage setting means.

[Function] According to the above configuration, electrothermal conversion is performed based on the resistance value, for example, voltage, of the dummy resistor that is manufactured in the same process as the electrothermal converter involved in ink ejection and has the same resistance value. A driving voltage to be applied to the body is determined.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a partial cross section of a recording head unit showing an embodiment of the present invention.

In FIG. 1, l1 is a heating resistor provided in each ink nozzle lO, and by driving these heating resistors 11 based on a recording data signal, the ink 12 in the ink nozzle 10 is heated. Bubble 13 grows,
Flying ink droplets 14 are formed by the expansion force of the bubble 13 and are attached to the recording medium 1 to form recording dots.

Reference numeral 33 denotes a dummy resistor composed of a heat generating resistor that is not involved in ejecting ink, and is produced in the same process of making the heat generating resistor 11 in the process of producing the head unit 6, with only the wiring being different. By doing as described above, the resistance value of the dummy resistor 33 can be taken as the resistance value of the heating resistor 11 because variations in the heating resistors made from the same chip can be ignored.

FIG. 2 is a perspective view showing the main structure of an inkjet recording apparatus suitable for carrying out the present invention.

In FIG. 2, a recording medium l such as a paper or a plastic sheet is supported by conveying rollers 2 and 3, each consisting of a pair of rollers placed above and below the recording position, to form a recording surface, and is conveyed in the eight directions of the arrows. be done. A guide shaft 4.4 is provided parallel to the conveyance rollers 2, 3, and the carriage 5 is reciprocated in the direction of arrow B along the guide shafts 4, 4.

A valve jet type recording head unit 6 is mounted on the carriage 5.

The front side of this recording head unit 6, that is, the recording medium 1
A plurality of ink nozzles 10 are formed in a vertical row on opposite surfaces with a predetermined gap, for example, +1.8 mm.

FIG. 3 is a block diagram showing the main structure of an inkjet recording apparatus according to an embodiment of the present invention.

In FIG. 3, a CPII 20 of the recording apparatus controls motors 22 such as a carriage motor and a recording medium transport motor via a motor driver 2l, and also controls a head controller 23 and a head driver 24 mounted on a recording head unit 6. The ink ejection at the ink nozzle IO is controlled via the ink nozzle IO. Further, starting, stopping, etc. of the recording apparatus are performed by operating the panel switch 25 via the CP020.

Further, a power supply circuit 26 for driving the head is connected to the head controller 23, and the drive voltage is applied to the heat generating resistor 11 of a predetermined ink nozzle 10 based on the print data signal.

FIG. 4 is a circuit diagram showing details of the configuration shown in FIG. 3.

In the figure, in the power supply circuit 26, the output terminal of an operational amplifier 28 is connected to the base of a transistor 27, the collector side of the transistor 27 is connected to the power supply VIN, and a reference voltage 8 is applied to the negative input terminal of the operational amplifier 28. Further, the positive side input terminal is connected to the voltage dividing point of the resistors R1 and R2 on the emitter side of the transistor 27 as shown in the figure. This constitutes a constant voltage power supply circuit 26.

Furthermore, as shown in the connection of the dummy resistor 33 made simultaneously with the heat generating resistor 11 through the photo-etching process, in this embodiment, the head drive voltage is set based on the resistance value of the dummy resistor 33, that is, the heat generating resistor 11. Ru. This will be explained below.

Generally, the energy for ejecting the ink droplet 14 is supplied by thermal energy for generating the bubble 13. That is, the thermal energy (
Ink droplets 14 are ejected by Joule heat. Therefore, irrespective of variations in the heating resistor 11, by always supplying constant Joule heat, constant discharge is possible.

To achieve this, dummy resistor 3 is used as shown in the figure.
3, a constant current source 32 constituted by an operational amplifier or the like is provided so that a constant current flows. That is, the constant current source 32 always supplies a constant current to the dummy resistor 33.

The terminal voltage based on the resistance value unique to the dummy resistor generated at this time is amplified by the amplifier 34 and supplied to the CPU 20 via the A/D converter 3l. The CPU 20 adds a preset correction value to the supplied voltage value information, and outputs the head voltage information to the power supply circuit 2 via the D/A converter 30.
Output to 6.

The voltage value information from the D/A converter 30 is sent to the power supply circuit 26.
Reference voltage V at . connected to adjust. That is, the reference voltage VR of the operational amplifier 28 changes by adding the voltage from the D/A converter 30 to the fixed voltage V++o. As a result, the base voltage of the transistor 27 changes, and the output of the power supply circuit 26, that is, the head drive voltage . is adjusted.

FIG. 5 is a block diagram similar to that shown in FIG. 3, according to a second embodiment of the present invention. The difference from the configuration shown in FIG. 3 is that the voltage value information detected at the dummy resistor 33 is supplied to the power supply circuit 26 via the differential amplifier circuit 35, not via the CPU 20.

FIG. 6 is a detailed circuit diagram similar to that shown in FIG. 4, including the power supply circuit 26 described above.

In FIG. 6, the dummy resistor 33 is connected to the power supply voltage v0 via the resistor RIO, whereby a voltage based on the unique resistance value of the dummy resistor 33, that is, the heating resistor 1l is detected. This detected voltage is applied to the differential amplifier circuit 35.
The reference potential in the power supply circuit 26 is changed in the same way as described above in the first embodiment.

The power supply circuit 26 sets the reference voltage ■ so that if the output from the differential amplifier circuit 35 is Ov, it outputs the standard head voltage.

. Set. The value of the resistor RIO is the same as the standard value of the dummy resistor 33 known in advance, and the value of the dummy resistor 33 is
When the terminal voltage of the differential amplifier circuit 3 is 1/2VI,
The comparison reference voltage Vs in the differential amplifier circuit 35 is set to 1/2 VD so that the output from the differential amplifier circuit 35 becomes 0■.

Note that the resistors Rll, Rl2,
The values of R13 and R14 are determined based on the maximum value, minimum value, and standard value of the dummy resistor 33, and the head voltage value in the standard state.

As explained above, since there is no need to adjust the head drive voltage unique to each recording head, production costs are reduced, assembly costs are reduced, and serviceability is improved.

[Effects of the Invention] As is clear from the above description, according to the present invention, electrothermal conversion is performed based on the resistance value, for example, voltage, of a dummy resistor having the same resistance value as the electrothermal transducer involved in ink ejection. A driving voltage to be applied to the body is determined.

11 As a result, the complicated adjustment and installation work required to set different head drive voltages for each recording head can be completely eliminated, resulting in lower manufacturing costs and improved assembly workability and service workability. It was done.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a partial cross-section of an inkjet recording head according to an embodiment of the present invention, FIG. 2 is a perspective view showing the main structure of an inkjet recording apparatus according to the embodiment, and FIG. FIG. 4 is a circuit diagram showing details of the configuration shown in FIG. 3; FIG. 5 is a block diagram showing the configuration of main parts of a recording device according to one embodiment; FIG. FIG. 6 is a block diagram showing the configuration of main parts. FIG. 6 is a circuit diagram showing details of the configuration shown in FIG. 5. l2 6... Recording head unit, 10... Ink nozzle, 11... Heat generating resistor, 20... CPU, 26... Power supply circuit, 33... Dummy resistor, 35... Differential Amplification circuit.

Claims (1)

[Scope of Claims] 1) A recording head that ejects ink by heating with an electrothermal transducer, and an electrothermal transducer that is manufactured in the same way as the electrothermal transducer and does not participate in ink ejection during the manufacturing process of the recording head. a dummy resistor configured as; a resistance detection means for detecting a value related to the resistance value of the dummy resistor; and a drive voltage setting that determines a voltage to be applied to the electrothermal transducer based on the value detected by the resistance detection means. An inkjet recording device characterized by comprising: means.