JP2000085128A - Printer, and print head temperature detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure correct temperature control of a print head by detecting temperature at a predetermined position of a print head through a temperature detecting means and correcting the detected temperature based on the positional relationship between a plurality of print elements and the temperature detecting means and the density of a print made by the print elements. SOLUTION: A plurality of heating elements are formed in row on a substrate constituting a print head 10 and diodes are fabricated, as temperature detecting elements constituting a temperature sensor 230, on the opposite sides of the arranging direction of the heating elements. A CPU 200 receives temperature of the head 10 detected by the sensor 230 and utilizes the detected temperature as a data for temperature controlling the head 10. The CPU 200 corrects the temperature detected through the diodes while taking account of the positional relationship between the diodes and each heating element and the heating conditions of each heating element. Consequently, temperature of the print head can be detected and controlled correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus for printing an image using various print heads such as an ink jet head, and a method for detecting a temperature of the print head.

[0002]

2. Description of the Related Art As a printing apparatus, for example, there is an ink jet printing apparatus for printing an image using an ink jet head capable of discharging ink by using thermal energy from a heating element.

Conventionally, as a method of detecting the temperature of an ink jet head in such an ink jet printing apparatus, a method of contacting a thermistor with the outside of a substrate on which a heating element is mounted and detecting a change in the resistance value of the thermistor corresponding to the temperature, Form a diode on the substrate on which the heating element is placed,
There is a method of detecting a change in the forward voltage of the diode corresponding to the temperature.

[0004]

[Problems to be Solved by the Invention] In such an ink jet printing apparatus, in the future, higher image quality,
Various print performances such as high resolution and high speed are required,
Accurate temperature control of the ink jet head is required for miniaturization, multiple nozzles, low cost, and high image quality of the ink jet head.

However, in the case of the temperature detection method using a thermistor as described above, it is difficult to accurately detect the temperature of the substrate because the thermistor is brought into contact with the outside of the substrate on which the heating element is mounted. Since the thermistor must be mounted outside the device, the physical space increases, which goes against miniaturization and costs.

On the other hand, in the case of the temperature detection method using a diode, the temperature of the substrate can be directly and accurately detected, and the detected temperature is used to finely control the temperature of the head, thereby achieving high image quality. , Higher resolution, and higher printing speed are possible. However, with the increase in the speed of printing and the increase in the size of the ink jet head due to the increase in the number of nozzles of the ink jet head, the temperature measurement position on the substrate provided with a diode as a temperature sensor and the heat generation provided with each heating element for a number of nozzles The distance from the position increases, and the temperature of the substrate cannot be accurately detected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus which accurately detects the temperature of a print head and, for example, controls the temperature of the print head properly using the accurate detected temperature, and the temperature of the print head. It is to provide a detection method.

[0008]

According to the present invention, there is provided a printing apparatus for printing an image on a printing medium by using a print head having a plurality of print elements. Based on the temperature detection means to be detected, the positional relationship between the plurality of print elements and the temperature detection means, and the density of the print corresponding to the heat value of the print elements, the detected temperature of the temperature detection means is determined. And a correcting means for correcting.

The temperature detecting method for a print head according to the present invention is used in a printing apparatus for printing an image on a print medium, and detects the temperature of a print head having a plurality of printing elements. A temperature at a predetermined position in the head is detected by temperature detecting means, and based on a positional relationship between the plurality of printing elements and the temperature detecting means, and a print density corresponding to a heating value of the printing elements, It is characterized in that the temperature detected by the temperature detecting means is corrected.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic perspective view of an ink jet printing apparatus to which the present invention can be applied.

In the ink jet printing apparatus 100, a carriage 101 is slidably engaged with two guide shafts 104 and 105 extending parallel to each other. As a result, the carriage 101 reciprocates in the main scanning direction indicated by the arrow X along the guide shafts 104 and 103 by the driving motor and a driving force transmission mechanism (not shown) such as a belt for transmitting the driving force. Be moved. An ink jet unit 103 is mounted on the carriage 101. The unit 103 has an ink-jet head described later and an ink tank as an ink container that stores ink used in the head. The head and the ink tank are configured to be detachable individually or integrally.

A sheet 106 as a medium to be printed is inserted from an insertion port 111 provided at the front end of the apparatus, and its transport direction is reversed. Y
In the sub-scanning direction. The head mounted on the carriage 101 prints an image on a print area on the paper 106 supported by the platen 108 as the head moves.

As described above, while the printing accompanying the movement of the carriage 101 in the main scanning direction, that is, the printing of the width corresponding to the width of the ejection opening array of the head, and the conveyance of the paper 106 in the sub-scanning direction are alternately repeated. Printing is performed on the entire sheet 106, and then the sheet 106 is discharged to the front of the apparatus.

At the left end of the movable area of the carriage 101, there is provided a recovery system unit 110 which can face the head on the carriage 101. The non-printing operation allows the recovery system unit 110 to perform operations such as capping each ejection port of the head and suctioning ink from each ejection port. The predetermined position at the left end of the apparatus is set as the home position of the head.

On the other hand, an operation unit 107 having a switch and a display element is provided at the right end of the apparatus. The switch is used for turning on / off the power of the apparatus, setting various print modes, and the like, and the display element displays various states of the apparatus.

FIG. 4 is a perspective view of a main part for explaining a configuration example of the ink jet head.

In FIG. 4, reference numeral 1 denotes a substrate on which a liquid path wall 2 is formed, and an ink jet head 10 is formed by joining the substrate 1 and a top plate 3. The ink is
The liquid is supplied into the common liquid chamber 5 of the head 10 through the supply pipe 4. The ink supplied into the common liquid chamber 5 is supplied into the ink flow path 6 by capillary action, and is stably held by forming a meniscus at the discharge port 7 at the tip of the ink flow path 6. By energizing the heating element (electrothermal conversion element) 8 located in the ink flow path 6, the ink on the heating element 8 is heated, and a bubbling phenomenon occurs in the ink, and the energy of the bubbling is generated. Accordingly, ink droplets are ejected from the ejection port 7. 9 is an energizing line for energizing the heating element 8. In this manner, for example, the ejection ports 7 are arranged at a high density of 400 dpi, and the inkjet head 10 having multiple ejection ports is configured.

FIG. 5 is a block diagram of a control system of the ink jet printing apparatus of FIG.

Referring to FIG. 5, a CPU 200 executes control processing of the operation of each section of the apparatus, data processing, and the like. RO
The processing procedure and the like are stored in the M200A.
00B is used as a work area for executing the processing.

The ink jet head 10 is configured as shown in FIG. 4 described above, and the CPU 200 transmits driving data and a driving control signal of the heating element 8 to the head driver 10A.
To discharge ink droplets.
As will be described later, the CPU 200 inputs the temperature of the head 10 detected by the temperature sensor 230, and uses the detected temperature as data for controlling the temperature of the head 10. The CPU 200 controls the carriage motor 210 for moving the carriage 101 via the motor driver 210A, and also controls the motor driver 22A.
A paper feed (PF) motor 220 for rotating the feed roller 109 is controlled via the line OA. FIG. 1 is a plan view of the substrate 1 in the inkjet head 10.

The substrate 1 has a plurality of heating elements 8 formed in rows. The substrate 1 constitutes an ink jet head 10 as shown in FIG. 4, and ink droplets are ejected from ejection ports 6 corresponding to each heating element 8 by thermal energy generated from the heating element 8. The substrate 1 has two diodes D1 and D2 serving as temperature detecting elements constituting the temperature sensor 230 so as to be located on both sides in the direction in which the heating elements 8 are arranged.
D2 is built. The diodes D1 and D2 are connected between the extraction terminals 21 and 22 by wires 23 and 24,
25 are connected in series. And terminals 21, 2
2, by measuring the forward voltage of the diodes D1 and D2 corresponding to the temperature, the temperature Ts of the head 10 is measured.
Is detected.

The temperature sensor 230 includes diodes D1, D
The temperature Ts detected by the diodes D1 and D2 is corrected in consideration of the thermal effect of each heating element 8 on the temperature 2. In the case of this example, the positional relationship between the diodes D1 and D2 and each heating element 8,
In consideration of the heat generation state of each heating element 8, the detected temperature Ts
Is corrected. At the time of the correction, B1, B in FIG.
2,..., Bn-1, Bn, the heating element 8 can be handled in a plurality of group units. In that case, the correction value ΔT of the detected temperature Ts can be obtained by the following equation (1).

ΔT = Tk * At (a1 * B1 + a2 * B2 +... + A (n-1 * Bn-1 + an * Bn)) (1) In the above equation (1), Tk is a temperature coefficient, At , Bn-1, Bn are the print densities of the blocks B1, B2,..., Bn-1, Bn, a1, a2,. 1) and an are coefficients for each block B1, B2,..., Bn-1, Bn. Print density At, B1, B2,... Bn−
1, Bn can be obtained from the print data.

Hereinafter, the heating elements 8 will be referred to as B1, B2, B3, B4
A specific method of correcting the detected temperature will be described with an example of the case of dividing into four groups.

As shown in FIG. 2, the heating elements 8 are B1, B2, B
3 and B4, the detection temperature Ts
Can be obtained by the following equation (2). ΔT = Tk * At (a1 * B1 + a2 * B2 + a3 * B3 + a4 * B4) (2) Temperature coefficient Tk and each block B1, B2, B3, B
The coefficients a1, a2, a3, and a4 for each of the four values vary depending on the configuration of the head, such as the heat capacity, heat transfer, and heat radiation state of the head. In the experimental example, Tk = 12, a1 = −1.2,
By setting a2 = 1, a3 = 1, and a4 = -1.2, the measured values coincided with the measured values of the head temperature. The above equation (2) is converted into the following equation (3) by substituting such specific coefficients.
Becomes

ΔT = 12 * At {(−1.2 * B1) + B2 + B3 + (− 1.2 * B4)} (3) As a specific example, when printing the print sections L1 and L2 in FIG. The print densities B1, B2, B3, and B4 of FIG. In FIG. 2, P1, P2, P3, P
Reference numeral 4 denotes a print range printed by the B1, B2, B3, and B4 blocks of the ejection port.

First, in the print section L1, B1
Only the print range P1 corresponding to 100% of the block is printed. That is, the entire print range P1, P2,
1/4 of P3 and P4 are printed, and the print density At becomes 0.25 (= 1/4). Also, B
The print density B1 of one block is 100%, the print density B2 of the B2 block is 0%, the print density B3 of the B3 block is 0%, and the print density B4 of the B4 block is 0.
%, B1 = 1, B2 = 0, B3 = 0, B4 =
It becomes 0. By substituting these values into the above equation (3), the temperature correction value ΔT in the print section L1 is obtained as in the following equation.

ΔT = 12 * 0.25 * (− 1.2 * 1) = − 3.6 Therefore, the temperature Ts detected by the diodes D1 and D2
Is corrected by subtracting 3.6 ° C., and the corrected temperature is used as head temperature control data.

On the other hand, in the print section L2, B1
Half of the print range P1 corresponding to 50% of the block is printed, and the print range P2 corresponding to 100% of the B2 block is printed. That is, 3/8 of the entire print range P1, P2, P3, P4 is printed, and the print density At is 0.37 (= 3
/ 8). Also, the print density B1 of the B1 block
Is 50% and the print density B2 of the B2 block is 100
%, The print density B3 of the B3 block is 0%, and the print density B4 of the B4 block is 0%, so that B1 = 0.
5, B2 = 1, B3 = 0, B4 = 0. By substituting these values into the above equation (3), the temperature correction value ΔT in the print section L2 is obtained as in the following equation.

ΔT = 12 * 0.375 * {(-1.2 * 0.5) + (1 * 1)} = 1.8 Therefore, the temperature Ts detected by the diodes D1 and D2
Is corrected by adding 1.8 ° C., and the corrected temperature is used as temperature control data for the head.

As described above, the temperature correction value ΔT is added to the temperature Ts detected by the diodes D1 and D2 as the temperature detecting elements in consideration of the heat generation state of each heating element 8.
The temperature of the head can be accurately detected, and as a result,
The temperature control of the head can be appropriately performed.

(Other Embodiments) The number of blocks for dividing the plurality of heating elements 8 is not limited to only the four blocks as described above, but is set to an arbitrary number of blocks according to the form of the head and the like. can do. In addition, the temperature correction value ΔT may be obtained in consideration of the individual heat generation state of the heat generating element 8 instead of the block.

The print density At and the print densities B1, B2,..., Bn-1, Bn actually change not only in the above-mentioned easily conceivable numerical values but also in the actual case. Further, the length and number of print sections such as L1 and L2 can be appropriately set in consideration of the storage capacity of data, the detection timing of temperature detection, and the like.

Further, as the ejection energy generating means for ejecting the ink droplets, various means such as a piezo element can be employed in addition to the heating element 8 serving as an electrothermal converter. Further, the present invention can be widely applied to a printing apparatus using a print head provided with various printing elements, such as a thermal transfer type print head, in addition to an ink jet printing apparatus using an ink jet head.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection, particularly in an ink jet printing system. An excellent effect is obtained in a print head (hereinafter, also referred to as a "recording head") and a printing apparatus (hereinafter, also referred to as a "recording apparatus") of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, 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 on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even in the case of the serial type as described above, a recording head fixed to the apparatus main body or an electric connection with the apparatus main body or ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are not limited to those provided only for one color ink, for example, and for a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet system generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not only used as an image output terminal of an information processing apparatus such as a computer, but also for a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may take a form.

[0045]

As described above, according to the present invention, the temperature at a predetermined position in the print head is detected by the temperature detecting means, and the positional relationship between the plurality of printing elements in the print head and the temperature detecting means is determined. The temperature of the print head can be accurately detected by correcting the temperature detected by the temperature detecting means based on the density of printing by the print element.

As a result, for example, appropriate temperature control of the print head can be performed using the accurate detected temperature.
It is possible to realize a longer life of the print head as well as higher image quality, higher resolution, and higher speed of the print.

[Brief description of the drawings]

FIG. 1 is a plan view of a substrate of a head according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of print density in an embodiment of the present invention.

FIG. 3 is a perspective view of an inkjet printing apparatus to which the present invention can be applied.

FIG. 4 is a perspective view of a partially cut-out portion of an inkjet head applicable to the inkjet printing apparatus of FIG. 3;

FIG. 5 is a block diagram of a control system of the inkjet printing apparatus of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Liquid path wall 3 Top plate 4 Supply pipe 5 Common liquid chamber 6 Ink flow path 7 Discharge port 8 Heating element (electric heat conversion element) 9 Electricity line 10 Inkjet head 10A Head driver 21, 22, Terminals 23, 24, 25 Wiring 200 CPU 200A ROM 200B RAM 210 Carriage motor 210A Motor driver 220 F motor 220A Motor driver 230 Temperature sensor D1, D2 Diode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tomoyuki Hiroki Inventor, 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Teruo Ozaki 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon F term in reference (reference) 2C056 EA04 EB07 EB30 EC07 EC29 2C057 AF22 AG12 AG46 AK20 AL25 AL28 AR20 BA05 BA13 DA10 DB01 DB03 DC08 DD06 DE05 EC06

Claims (11)

[Claims] 1. A printing apparatus for printing an image on a print medium using a print head having a plurality of print elements, comprising: a temperature detecting unit for detecting a temperature at a predetermined position in the print head; Correcting means for correcting the temperature detected by the temperature detecting means based on a positional relationship between the element and the temperature detecting means and a print density corresponding to a heat value of the printing element. Printing device. 2. The printing apparatus according to claim 1, wherein the correction unit corrects the temperature detected by the temperature detection unit for each predetermined printing section by the print element. 3. The printing apparatus according to claim 2, wherein the correcting unit divides the plurality of printing elements into a plurality of blocks according to a distance from the temperature detecting unit, and obtains a print density for each block. 3. The printing device according to 1 or 2. 4. The correction means divides the plurality of print elements into a plurality of blocks according to a distance from the temperature detection means, Tk represents a temperature coefficient, At represents a print density in a predetermined print section, B1 , B2, ..., Bn-
1, Bn is the print density of each block, a1, a2,
.., A (n−1) and an are replaced with each block B1, B2,.
2. The printing apparatus according to claim 1, wherein a correction value [Delta] T of the temperature detected by the temperature detecting means is obtained from the following equation as a coefficient for each of Bn-1, Bn. ΔT = Tk * At (a1 * B1 + a2 * B2 +... +
a (n-1 * Bn-1 + an * Bn)) 5. The print head according to claim 1, wherein the print head is an ink jet head capable of discharging ink droplets from a plurality of discharge ports by discharge energy generated by a plurality of discharge energy generating means. The printing device according to any one of the above. 6. The printing apparatus according to claim 5, wherein said discharge energy generating means is an electrothermal converter that generates heat energy as discharge energy for discharging ink. 7. The plurality of electrothermal transducers are formed in a row on a substrate of the print head, and the temperature detecting means is arranged so as to be located on both sides of the row of the plurality of electrothermal transducers. The printing apparatus according to claim 6, wherein a plurality of the printing apparatuses are provided on a substrate. 8. The printing apparatus according to claim 1, wherein said temperature detecting means is a diode whose forward voltage changes according to a temperature. 9. The printing apparatus according to claim 1, further comprising a unit that controls the temperature of the print head based on the temperature detected by the temperature detecting unit corrected by the correcting unit. Printing equipment. 10. A first moving means for relatively moving the print head and the print medium in the main scanning direction, and relatively moving the print head and the print medium in a sub scanning direction intersecting the main scanning direction. The printing apparatus according to any one of claims 1 to 9, further comprising a second moving unit configured to perform the operation. 11. A temperature detecting method for detecting the temperature of a print head, which is used in a printing apparatus for printing an image on a print medium and includes a plurality of print elements, comprises detecting the temperature at a predetermined position in the print head. The temperature detected by the temperature detector is corrected based on a positional relationship between the plurality of print elements and the temperature detector, and a print density corresponding to a heat value of the print element. A method for detecting the temperature of a print head.