JPH04164648A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To improve a quality of a recorded image by a method wherein a temp. in the vicinity of a delivery port is detected in synchronism with the completion of an inks delivery out of the delivery port, a next drive pulse width at the delivery port is calculated on the basis of the detected temp., and a drive pulse width at the delivery port is controlled on the basis of the calculated pulse width so that the temp. of a recording head is kept within a predetermined range. CONSTITUTION:In an ink jet recorder, the temp. of a recording head 1 is controlled to be a predetermined range by a temperature detection means 43 detecting a temp. in the vicinity of a delivery port in synchronism with the completion of an ink delivery out of the delivery port 22, pulse width calculation means 34, 35 calculating a next drive pulse width at the delivery port 22 on the basis of the detected temp., and a pulse width control means 44 controlling a drive pulse width at the delivery port 22 on the basis of the calculated pulse width. In synchronism with the completion of an ink delivery out of the delivery port 22, a temp. in the vicinity of the delivery port is detected. Based on said temp., an ink delivery drive pulse width at the delivery port 22 is controlled to be within a set range. In this manner, the temp. of the recording head 1 can be stabilized, an ink delivery amount for every drive of the delivery port 22 is kept uniform, and an image quality can be improved.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink from a recording head onto a recording material. [Prior Art] Recording devices such as printers, copying machines, and facsimile machines are configured to form images on recording materials such as paper and thin plastic plates based on image information. The recording device may be an inkjet type,
It can be divided into wire dot type, thermal type, laser beam type, etc. Among them, inkjet type (inkjet recording apparatus) is configured to perform recording by ejecting ink from a recording head onto a recording material. Inkjet recording devices can record high-definition images at high speed, use a non-impact system, making less noise, and can easily record color images using multicolored inks. It has advantages. In this inkjet recording device, if the temperature of the recording head changes and the viscosity of the ink changes, the amount of ink ejected may fluctuate or ejection may become impossible, and the quality of the printed image may deteriorate. A temperature control means is provided to control the temperature of the recording head within a predetermined range. Conventionally, a temperature control means for a recording head includes a temperature sensor that generates a signal proportional to the temperature of the entire recording head, and generates a drive signal based on a comparison between a detected value from the temperature sensor and a preset value. It consisted of a control circuit and a heating element that heated the entire recording head based on a drive signal from the control circuit. [Technical problem to be solved by the invention] However,
Conventional inkjet recording devices of this type had a technical problem in that when the ambient temperature was higher than the target temperature, the heating element could no longer control the temperature of the recording medium and did not operate effectively. . In particular, after the start of recording, the temperature near the ejection port changes dynamically mainly due to the on/off of the ejection port drive signal, but the conventional temperature control means cannot follow this.
It has been customary for the temperature of the recording head to rise as recording progresses. For this reason, as printing progresses, the fluidity of the ink increases and the amount of ink ejected from the ejection ports per drive increases, resulting in a technical problem of uneven printing density. The present invention has been made in view of such technical problems, and an object of the present invention is to stabilize the temperature of the recording head and make the amount of ink ejected per drive of the ejection ports uniform. An object of the present invention is to provide an inkjet recording device that can improve the quality of recorded images. [Means for Solving the Problems] The present invention provides an inkjet recording apparatus that performs recording by ejecting ink from an ejection port of a print head onto a recording material. Temperature detection means for detecting temperature; pulse width calculation means for calculating the next drive pulse width of the discharge port based on the detected temperature; and pulse width control that controls the drive pulse width of the discharge port based on the calculated pulse width. The above object is achieved by controlling the temperature of the recording head within a predetermined range using means.

【Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 4 is a perspective view schematically showing the structure of an embodiment of an inkjet recording apparatus according to the present invention. In FIG. 4, a carriage 3 carrying a recording head 1 and an ink tank 2 is movably guided and supported along a guide rail 4, and is driven back and forth by a carriage motor 6 via a timing belt 5. A sheet-like recording material 7 made of paper, a thin plastic plate, etc. is transported by a pair of conveyance rollers 9 driven by a conveyance motor (paper feed motor) 8 and a pair of holding rollers 10 that cooperate with the conveyance roller pair 9.
Accordingly, the paper is transported (paper fed) in the direction of arrow f along a predetermined path at a predetermined timing and a predetermined pitch. While this recording material 7 is held flat at the recording position facing the ink ejection part of the recording gutter 1, the carriage 3
・Recording is performed while main scanning at 7 dots 1, and when recording for one line is completed, the recording material 7
is pitch-fed by the recording width in the direction of arrow f, and recording of the next recording width is performed. Ink tank 2 for supplying ink to the recording head 1
is mounted replaceably on the carriage 3. Further, a home position H is set at a predetermined position within the movement range of the carriage 3 and outside the recording area, and a recovery device 14 for recovering ink failure of the recording head 1 is disposed at the home position H. It is set up. The recovery device 14 is provided with a cap 15 for sealing the ink ejection section of the recording head 1. The recording head 1 is an inkjet recording head that discharges ink using thermal energy, and is equipped with an electrothermal converter for generating thermal energy. Further, this inkjet recording head l performs recording by ejecting ink from an ejection port by utilizing pressure changes caused by growth and contraction of bubbles due to film boiling caused by thermal energy applied by the electrothermal converter. It is something. FIG. 5 is a partial perspective view schematically showing the structure of the ink ejection section of the recording head 1. As shown in FIG. In FIG. 5, the ejection port surface 2 faces the recording material 7 with a predetermined gap (for example, about 0.5 to 2.0 cm).
1, a plurality of discharge ports 22 are formed with a predetermined pinch,
An electrothermal converter (such as a heating resistor) 25 for generating energy for ink ejection is arranged along the wall surface of each liquid path 24 that communicates the common liquid chamber 23 and each ejection port 22. There is. In this example, the recording head 1 is mounted on the carriage 2 in such a positional relationship that the ejection ports 22 are lined up in a direction intersecting the scanning direction of the carriage 3. In this way, the corresponding electrothermal converter 25 is driven based on the image signal or the ejection signal, causing the ink in the liquid path 24 to film boil, and the pressure generated at that time causes the ink to be ejected from the ejection port 22. A recording head l is configured. FIG. 1 is a block diagram showing the configuration of an embodiment of a recording head drive system of an inkjet recording apparatus according to the present invention. In FIG. 1, 31 is a clock generation circuit; is a binary counter, 33 is a digital comparator, 34 is D
Latch register, 35 is AD funverter, 36 is R
S flip-flop, 37 is a constant current source, 38 is a temperature detection diode, 39 is an operational amplifier, PR3T is a carrier,
The output pulse of the rotary encoder attached to the rotating shaft of the motor 6, HEAT, is an ejection drive pulse signal (dot drive signal) for causing the electrothermal converter 25 of the ejection port 22 of the recording head 1 to generate heat. 1 and 4, when main scanning is started by driving the carriage 3 during the recording operation, the flip-flop 36 is set by the output pulse PR3T of the rotary encoder, and the ejection drive pulse signal HEA
T becomes active (on). At the same time, the binary counter 32 starts counting the number of clock pulses of the clock generation circuit 31. On the other hand, the previous AD value is loaded into the D latch register 34 via the AD converter 35. Therefore, the digital comparator 33
The count value of the advance counter 320 is compared with the AD value loaded in the D latch register 34, and if they match, the flip-flop 2 pin 36 is reset by the output from the digital comparator 33, and the ejection drive pulse signal is HEAT becomes inactive (off). Through the above-described operation, the ejection drive pulse signal HEAT having a predetermined width is outputted to the print head drive circuit every fixed cycle, and ink is ejected from the ejection ports 22 to perform printing. At this time, the AD converter 35 starts AD conversion. For this AD converter 35, a constant current source 37,
A temperature detection signal is inputted from the temperature detection means, which consists of a temperature detection diode 38 and an operational amplifier 39, and is configured to detect the temperature near the ejection port in synchronization with the end of ink ejection from the ejection port 22. Temperature adjustment of the ink ejection drive pulse width is performed. When the AD conversion is completed, the result is loaded into the D latch register 34 by the EOC signal output from the AD converter 35. The value loaded into this D latch register 34 becomes the sequence parameter of the next ink ejection drive restarted by the next PRST signal of the rotary encoder. FIG. 2 shows each signal in the control operation of the 7-drive drive system recorded above, namely, the rotary encoder output pulse PR5T, the ejection drive pulse signal HEAT, the AD conversion start signal 5TAR of the AD converter 35 from the flip-flop 36, 3 is a timing chart of an EOC signal outputted from the AD converter 35 to the D latch register 34 and an ADD signal inputted from the AD converter 35 to the D latch register 34. FIG. 3 is a plan view showing the configuration of the temperature control circuit of the recording nozzle. In FIG. 3, a silicon chip 41 is bonded to the surface of an aluminum substrate 40 of the recording head.
1, a control logic 42, a temperature sensor 43, and a heater driver circuit 44 are formed. Further, an auxiliary heater 45 is provided on the silicon chip 41. The heater driver circuit 44 includes an electrothermal converter (heater) 25 shown in FIG. 5, and constitutes a drive pulse generation circuit for ejecting ink from the ejection ports 22. For example, when the temperature measured by the temperature sensor 43 is 25°C or less during recording standby, a small current that does not eject ink is applied to the heater driver circuit 44, and the auxiliary heater 45 controls the recording head 1. Heat. With the above configuration, the inkjet recording device of the present invention,
That is, in an inkjet recording apparatus that performs recording by ejecting ink onto a recording material 7 from an ejection port 22 of a gutter 1, temperature detection detects the temperature near the ejection port in synchronization with the completion of ink ejection from the ejection port 22. means 43, pulse width calculation means 34, 35 for calculating the next drive pulse width for the ejection port 22 based on the detected temperature, and pulse width control for controlling the drive pulse width for the ejection port 22 based on the calculated pulse width. An inkjet recording apparatus is provided which is characterized in that the temperature for recording is controlled within a predetermined range by means 44. According to the embodiment described above, the temperature near the ejection port is detected in synchronization with the end of ink ejection from the ejection port 22, and the ink ejection drive pulse width (dot drive pulse width) of the ejection port 22 is determined based on the detected temperature. ) within a set range, the temperature of the recording head 1 can be stabilized, and the ink ejection amount per drive of the ejection ports 22 can be maintained uniformly, thereby improving image quality. was gotten. In the above embodiments, the case of a serial type inkjet recording apparatus in which the recording head l is mounted on the carriage 3 that moves along the recording material 7 has been described as an example. The present invention can be similarly applied to line-type inkjet recording apparatuses that use line recording heads that cover all or part of the recording area, and can achieve similar effects. Furthermore, in the above embodiments, a case has been described in which the printing apparatus performs printing with one gutter, but the present invention is directed to a color inkjet printing bag that is equipped with a plurality of printing heads that print in different colors! , or an inkjet recording device for gradation recording using multiple recording heads with the same color but different densities, which can be applied in the same way regardless of the number of recording nodules and can achieve the same effects. be. The recording head 1 in the above embodiments may be a cartridge type recording head in which an ink ejection part and an ink tank are integrated, or a cartridge type print head in which an ink ejection part and an ink tank are separate parts and connected via a coupler and a tube, for example. Printheads with various structures can be used, such as a printhead with a structure or a printhead with a structure consisting only of ink ejection portions without an ink tank. In addition, the present invention is an inkjet recording bag! If so, it can be applied to recording heads that use electrothermal transducers such as piezo elements, but it is especially effective in inkjet recording devices using the Hubblejesoto method proposed by Canon Co., Ltd. It is something. This is because, according to such a method, high precision and high definition recording can be achieved. As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but in the case of the on-demand type, it is particularly important to By applying at least one drive signal to the disposed electrothermal transducer that corresponds to the recorded information and causes a temperature increase that is quadrupling faster than nucleate boiling,
This method is effective because it generates thermal energy in the electrothermal transducer to cause film boiling on the heat-active surface of the recording head, resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal. Due to the growth and contraction of these bubbles, liquid (
ink) to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately, so liquids with particularly excellent responsiveness (
Ink) can be ejected, which is more preferable. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 concerning the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be achieved. The configuration of the recording head includes, in addition to the combined configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. US Pat. No. 4,558,333 and US Pat. No. 4,459,600 disclose a configuration in which the
The present invention also includes a configuration using the specification of the above specification. In addition, Japanese Patent Application Laid-open No. 23670 of 1982 discloses a configuration in which a common thrift is used as a discharge part of a plurality of electrothermal transducers, and Japanese Patent Laid-Open No. 23670 discloses a configuration in which a common thrift is used as a discharge part of the electrothermal transducers, and a patent publication for absorbing pressure waves of thermal energy is also disclosed. The present invention is also effective with a configuration based on Japanese Patent Application Laid-Open No. 138461 of 1982, which discloses a configuration in which holes correspond to discharge portions. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently. Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus. Such a recording head may have a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally. In addition, even serial types such as top strips can be electrically connected to the device body and ink can be supplied from the device body by being attached to the recording head fixed to the device body or to the device body. The present invention is also effective when using a replaceable chiabut type recording head or a cartridge type recording head in which an ink tank is integrally provided in the recording head itself. Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus, to the present invention because the effects of the present invention can be further stabilized. Specifically, these include capping means, cleaning means, pressure or suction means, preheating means for the recording head using an electrothermal transducer or another heating element, or a combination thereof. It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing. In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to a single color ink, there are also multiple types installed to correspond to multiple inks with different recording colors and densities. It may be provided. That is, for example, the recording mode of the recording apparatus is not only a recording mode for mainstream colors such as black, but also whether the recording head is configured integrally or by a combination of multiple heads.
Although any of these may be used, the present invention is also extremely effective for devices equipped with at least one of multiple colors of different colors or full colors created by mixing colors. Additionally, in the embodiments of the present invention described above,
Although the ink is described as a liquid, it is an ink that solidifies at room temperature or below, but softens or liquefies at room temperature, or in the inkjet method, the ink itself is heated within a range of 30°C or higher and 70°C or lower. Since the temperature is generally controlled so that the viscosity of the ink is within a stable ejection range, it is sufficient that the ink is in a liquid state when the recording signal is applied. In addition, it is possible to proactively prevent temperature rise caused by thermal energy by using it as energy to change the state of the ink from a solid state to a liquid state, or to prevent ink from evaporating when the ink solidifies when left unused. In any case, the ink is liquefied by applying thermal energy in accordance with the recording signal, and the liquid ink is ejected, or the ink already begins to solidify by the time it reaches the recording medium. The present invention is also applicable when using ink that is liquefied only by thermal energy. In such cases, the ink is held in a liquid or solid state in the recesses or through holes of the porous sheet, as described in JP-A-54-56847 or JP-A-60-71260. , it may also be in a form that faces the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method. In addition, the inkjet recording device according to the present invention can be used as an image output terminal for information processing equipment such as a computer, a copying device combined with a league etc., or a facsimile device having a transmitting/receiving function. It may also be something that is harvested. [Effects of the Invention] As is clear from the above description, according to the present invention, in an inkjet recording apparatus that performs recording by ejecting ink from the ejection ports of the print head onto the recording material, the time required to complete ink ejection from the ejection ports is Temperature detection means for synchronously detecting the temperature near the discharge port; pulse width calculation means for calculating the next drive pulse width for the discharge port based on the detected temperature; and pulse width calculation means for calculating the next drive pulse width for the discharge port based on the calculated pulse width. Since the temperature of the print head is controlled within a predetermined range by the pulse width control means that controls the width, the temperature of the print head is stabilized and the amount of ink ejected per drive of the ejection port is made uniform. Accordingly, an inkjet recording apparatus capable of improving the quality of recorded images is provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a print head drive control system of an ink side printing apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart of each signal of the print head drive control system of FIG. 1, and FIG. FIG. 3 is a schematic plan view showing the configuration of a drive circuit for a recording head of an inkjet recording device according to an embodiment of the present invention, and FIG. 4 is a perspective view schematically showing the configuration of an embodiment of an inkjet recording device according to the present invention. 5 is a partial perspective view schematically showing the structure of the ink ejection section of the recording head in FIG. 4. Below, symbols representing main components in the drawings are listed. ! --- Recording belly button F', 3--- Carriage, 6--
--- Carriage motor, 7-- Recording material, 8 ・
---Transport motor, 14--Recovery device, 22-
...-Discharge port, 25---Electrothermal converter (heater), 33--Digital comparator, 34--
-D, Chile register, 36--Flip-flop,
42----Control ROSIC, 43---Temperature sensor, 44---Heater driver circuit, 45------
・Auxiliary heater, PH1T------ Carriage motor rotary encoder output, HE A T-
...-Discharge drive pulse signal. Figure 2 PR5T i(EAT AD[) t, t2

Claims (3)

[Claims] (1) In an inkjet recording device that performs recording by discharging ink from the discharge ports of a recording head onto a recording material,
temperature detection means for detecting the temperature near the ejection port in synchronization with the completion of ink ejection from the ejection port; and pulse width calculation means for calculating the next drive pulse width for the ejection port based on the detected temperature.
An inkjet recording apparatus characterized in that the temperature of the recording head is controlled within a predetermined range by pulse width control means that controls the drive pulse width of the ejection ports based on the calculated pulse width. (2) The recording head is an inkjet recording head that discharges ink using thermal energy, and includes an electrothermal converter for generating thermal energy. inkjet recording device. (3) The recording head is characterized in that the ink is ejected from the ejection port by utilizing a pressure change caused by the growth of bubbles due to film boiling caused by the thermal energy applied by the electrothermal converter. 2. The inkjet recording device according to 2.