JP2001063010A - Ink detection sensor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the reliability of a determination result by changing an ink ejection start position, an ejection cycle, an ejection frequency, and a carriage moving speed in accordance with the color of an ink to be detected. A detection unit that detects ink ejected from an inkjet head and outputs a detection signal, a unit that ejects ink near a detection position while moving the inkjet head, and a detection synchronized with ink ejection A unit for determining whether or not ink has been ejected based on a signal, wherein the detection unit is shaped so that ink ejected from the inkjet head does not penetrate into the interior of the detection unit from a portion where it lands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink detection sensor for detecting ink ejected from an ink jet head used in an ink jet recording apparatus.

[0002]

2. Description of the Related Art Hitherto, various recording apparatuses for recording on a recording medium such as paper, OHP sheet, etc. have been proposed.
Among them, an ink jet recording apparatus is to eject ink directly from a recording head onto recording paper, and is used as a recording apparatus having advantages such as low running cost and quiet recording operation.

In an ink-jet recording apparatus, as a method of detecting the presence or absence of ink in an ink tank (ink cartridge) provided in an ink-jet head, ink droplets are ejected between photo-interrupters, and the ink is discharged based on the output of the photo-interrupter. There is a method of detecting the presence or absence.

[0004]

However, in the conventional method, when ink is ejected between the photosensors, it is necessary to reduce the distance between the light emitting element and the light receiving element of the photosensor in order to improve the detection accuracy. . In this case, the ejected ink may land on the photosensor, and the ink may be permeated into the sensor due to a capillary phenomenon since the ink is a liquid from the joint of the exterior material of the sensor.

The present invention has been made in view of the above conventional example, and has a shape in which ink does not permeate into the sensor when the ink lands on the sensor when the ink is ejected to detect the ink. It is an object of the present invention to provide an ink detection sensor having a configuration.

[0006]

In order to achieve the above object, an ink detection sensor according to the present invention has the following arrangement.

That is, in an ink jet recording apparatus for performing recording using an ink jet head for discharging ink,
An ink detection sensor that is provided at a predetermined position in the moving area of the inkjet head and detects an ink ejected from the inkjet head and outputs a detection signal,
The ink detection sensor has a shape such that the ink does not penetrate into the sensor from a portion where the ink discharged from the inkjet head lands.

[0008]

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

FIG. 1 is a sectional view showing a facsimile apparatus using an ink detection sensor to which the present invention is applied. In FIG. 1, A is a recording unit that is an ink jet recording apparatus, B is a reading unit that optically reads a document, and C is a paper feeding unit that separates the loaded recording paper and supplies it to the recording unit.

Referring to FIG. 1, first, the flow of a recording material (hereinafter, referred to as recording paper) will be briefly described. A series of recording paper transport paths is indicated by an arrow G. In the present embodiment, a fixed cut sheet is used, and a plurality of sheets are stacked and stored in the auto sheet feeder 50. The auto sheet feeder 50 is configured so that the side surface of the recording paper can be guided by the slider 51 in accordance with the size of the recording paper.

First, the recording paper 12 stored and stacked in the automatic sheet feeder 50 is separated and conveyed by the paper feed roller 52 and a separation claw (not shown). After that, the sheet is nipped and conveyed by the conveying roller 5 and the roller 6 arranged opposite thereto.

In the recording unit, recording is performed by the recording head 1, and a discharge roller 9, which is located downstream of the recording head 1 and conveys printed recording paper 12 downstream of the apparatus,
The spur 8 is made of a material that is located on the opposite side of the discharge roller and does not transfer ink even when it comes into contact with the printing surface of the recording paper 12.

The recording paper conveyed by the paper discharge roller 9 and the spur 8 is discharged onto a recording paper discharge tray 55 provided below the apparatus main body 60.

Reference numeral 23 denotes a cover which can be opened and closed. When the cover is opened, a space required for replacing the recording head 1 is opened.

Next, the flow of a sheet material (hereinafter referred to as a document) will be described.

A series of document conveying paths are indicated by arrows F. The original is placed on the cover 23 which also serves as the original loading tray.
When one or more sheets are set, the presence thereof is detected by a document presence / absence sensor that detects the presence or absence of a document (not shown). Next, when the user depresses a start button (not shown) both at the time of transmission and at the time of copying, the separation roller 33 and the preliminary conveyance pressing arm which are rotated by a stepping motor (not shown) which is a driving source. The document is pinched by 32 and the leading edge is separated.

Thereafter, the originals are separated one by one in the case of a plurality of originals by a separating section constituted by the separating roller 33 and the friction piece unit 34, and the paper is rotated by the stepping motor. The document is nipped and conveyed by a paper feed roller 36 arranged opposite to the roller 35, and the leading end of the document is detected by a document leading and trailing edge sensor (not shown) for detecting the leading and trailing edges of the document.

Thereafter, while reading the image data of the original by the contact sensor 37 which is an original reading device, the trailing end of the original is detected by the original leading and trailing edge sensor. The paper discharge roller 38 rotated by the stepping motor is rotated by a predetermined amount in accordance with the output from the original leading and trailing edge sensor, and the original is rotated by a paper discharging roller 39 arranged to face the paper discharging roller 38. The document is nipped and conveyed, and is stacked on a cover 31 also serving as a document discharge tray.

Next, the configuration of the recording section A of this embodiment will be described in detail with reference to FIG. In FIG. 2, reference numeral 1 denotes a recording head. In this embodiment, an ink tank is incorporated, and a cartridge type ink jet recording head which can be replaced with a new recording head when the ink runs out is mounted.
Reference numeral 2 denotes a carriage for reciprocating in the direction perpendicular to the transport direction H (sub-scanning direction) of the recording paper 12, that is, in the main scanning direction E, while accurately holding the recording head 1. It is slidably held by 2a. The reciprocation of the carriage 2 is performed by a pulley 4 and a timing belt 3 driven by a motor (not shown). At this time, a print signal and electric power applied to the recording head 1 are supplied by a flexible cable 7 from an electric circuit of the main body. Supplied. The recording head 1 and the flexible cable 7 are connected by press-contacting their respective contacts.

Reference numeral 15 denotes a cap functioning as an ink receiving means. The cap 15 is installed in correspondence with a position (home position) where the carriage 2 is on standby, moves up and down as needed, and comes into close contact with the recording head 1 when ascending. The nozzle portion is covered to prevent evaporation of ink and adhesion of dust.

In this embodiment, in order to position the recording head 1 and the cap 15 so as to be relatively opposed to each other, the recording head 1 and the cap 15 are provided on the carriage home sensor 10 and the carriage 2 provided on the main body of the recording apparatus. The light shielding plate 2b is used. The carriage home sensor 10 is composed of a transmission type photo interrupter. When the carriage 2 moves to the standby position, light transmitted from a part of the carriage home sensor 10 is blocked by the light shielding plate 2b. This is used to detect that the recording head 1 and the cap 15 are at positions relatively opposed to each other.

The recording paper 12 is fed from the right side in the drawing, and is separated by a predetermined length by the conveying roller 5 and a bearing member (not shown), and is pressed against the conveying roller 5 by a pressing roller 6 in a direction indicated by an arrow H (see FIG. (Sub-scanning direction). The transport roller 5 and the discharge roller 9 are each driven by a drive system (not shown), and transport the recording paper 12 in the sub-scanning direction with high precision in conjunction with the reciprocation of the carriage 2 as needed.
Reference numeral 8 denotes a spur, which is made of a material having a high water repellency, and comes into contact with the recording paper 12 only at the recording paper surface and at the peripheral portion of the blade shape. The recording paper 12 is configured to be guided and conveyed without affecting the image even if it comes into contact with the unfixed ink on the recording paper immediately after printing.

According to the present invention, as shown in FIG. 2, an ink detecting sensor 44 for discriminating the presence or absence of ink by the ink ejected crossing the optical axis of the light emitting element and the light receiving element of the transmission type photo interrupter type sensor is provided as an ink receiving means. The sensor 44 is disposed on the opposite side of the cap 15 from the main scanning direction E and is scattered by ink when the recording head 1 is capped.
To prevent dirt.

In order to position the nozzle array of the recording head 1 and the ink detection sensor 44 so as to be relatively opposed to each other, similarly to the positioning with the cap 15,
The carriage home sensor 10 provided in the apparatus main body is used.

In this embodiment, the distance traveled from the home position (HP) to the optical axis of the ink detection sensor 44 is converted into the number of steps of a carriage motor 30 (not shown) for driving the carriage 2 and recorded in advance. It is set as a constant in the control program that executes the operation.

The recording head 1 used in the present embodiment discharges ink from the discharge port at the tip of the nozzle by the pressure of the film boiling generated in the ink by the heat generated by the electrothermal transducer provided in the nozzle. In the facsimile of the present embodiment, the recording head 1 has 128 nozzles and 36
A monochrome recording head for black ink arranged in accordance with a resolution of 0 DPI, a color recording head in which 64 nozzles for black ink, and 24 nozzles each corresponding to each color of yellow, magenta, and cyan are arranged in accordance with a resolution of 360 DPI. Can be used. Each of these two types of print heads has one nozzle row. For a color print head, one nozzle row is divided into a plurality of areas corresponding to each color, so that a nozzle row corresponding to each color is formed. It is configured. In addition, by using these two types of recording heads properly, two types of printing, that is, high-speed monochrome printing and high-definition full-color printing can be properly used.

Next, the principle of ejection of a recording head used as a recording means in the ink jet recording apparatus of the present embodiment will be described. A recording head section applied to an ink jet recording apparatus generally includes a fine liquid discharge port (orifice), a liquid path, an energy acting section provided in a part of the liquid path, and a liquid acting on the liquid in the acting section. An energy generating means for generating droplet forming energy is provided and is replaceable.

As an energy generating means for generating such energy, one using an electromechanical transducer such as a piezo element, or irradiating an electromagnetic wave from a laser or the like and absorbing the liquid there to generate heat. Then, there is a device that discharges and flies droplets by the action of the heat, or a device that discharges a liquid by heating a liquid with an electrothermal converter. Among them, a recording head portion used in an ink jet recording system in which a liquid is discharged by thermal energy has a high density of liquid discharge ports (orifices) for discharging a recording droplet to form a flying droplet. Therefore, it is possible to record at a high resolution.

A recording head using an electrothermal transducer as an energy generating means can easily be made compact as a whole as a recording head, and has recently made progress in technology in the semiconductor field and improved reliability. The advantages of IC technology and micro-machining technology, which are remarkable, can be fully utilized, and it is easy to increase the length and form the surface (binary). In addition, it is possible to provide an ink jet recording head unit which is mass-produced with high productivity and inexpensive in production cost.

In general, an ink jet recording head manufactured through a semiconductor manufacturing process using an electrothermal transducer as an energy generating means is provided with a liquid path corresponding to each ink ejection port. An electrothermal converter is provided as a means for applying thermal energy to the liquid filling the liquid path and discharging the liquid from the corresponding ink discharge port to form a flying droplet. Has a structure in which liquid is supplied from a common liquid chamber communicating with each liquid path.

FIG. 3 shows a schematic configuration of the above-described ink jet recording head. The recording head unit 101 has a hardened active energy having an electrothermal converter 103, an electrode 104, and a liquid path 110 formed on a substrate 102, which is a first substrate, through semiconductor manufacturing process steps such as etching deposition and sputtering. The line-curable material layer 105 and the top plate 1
06. Thus, in such a recording head unit 101, the recording liquid 112 is supplied from a liquid storage chamber (not shown) through the liquid supply pipe 107 into the common liquid chamber 108.

Reference numeral 109 denotes a liquid supply pipe connector. The recording liquid 112 supplied into the common liquid chamber 108 is supplied into the liquid path 110 by a capillary phenomenon, and is stably held by forming a meniscus at the ink discharge port 111 at the leading end of the liquid path. Then, when electricity is supplied to the electrothermal converter 103, the liquid on the electrothermal converter surface is heated, and a bubbling phenomenon occurs due to film boiling. With the above-described configuration, a multi-nozzle inkjet recording head can be formed with a high-density liquid pipe having a discharge port density of 360 to 400 dots / inch.

The present invention particularly provides an excellent effect in an ink jet recording apparatus which performs recording by forming flying droplets by utilizing thermal energy among ink jet recording methods.

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 can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
At least one drive signal corresponding to recorded information and giving a rapid temperature rise exceeding nucleate boiling is applied to an electrothermal transducer arranged corresponding to a sheet or a liquid path holding the liquid. As a result, heat energy is
This causes film boiling on the heat-acting surface of the recording head, and as a result, it is possible to form bubbles in the liquid (ink) in one-to-one correspondence with the drive signal. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. 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-angle liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600 which discloses a configuration in which the heat acting portion is arranged in a bending region may be adopted. In addition, Japanese Patent Laid-Open Publication No. Sho 5 discloses a configuration in which a common slit is used as a discharge section of an electrothermal converter for a plurality of electrothermal converters.
Japanese Unexamined Patent Publication No. 9-123670 discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge portion.
A configuration based on JP-A-9-138461 can also be adopted.

In addition, the print head is replaceable with a print head of a replaceable chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus, or integrated with the print head itself. Alternatively, a cartridge type recording head provided with an ink tank may be used.

It is preferable to add recovery means for the recording head, preliminary auxiliary means, and the like, since the effects of the present invention can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or sucking means, preheating means using an electrothermal converter or another heating element or a combination thereof, and recording. It is also effective to perform a preparatory ejection mode for performing another ejection in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, and the recording head may be integrally formed or a combination of a plurality of recording heads. The device may be provided with at least one of a multi-color color or a full-color color mixture.

In the embodiment of the present invention described above,
Although the ink is described as a liquid, any ink that solidifies at room temperature or lower and softens at room temperature or a liquid, such as a liquid, may be used as long as the ink is in a liquid state when a use recording signal is applied. .

In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from the solid state to the liquid state, or the ink can be left standing for the purpose of preventing the ink from evaporating. Either using ink that solidifies, or in any case, the ink is liquefied by applying heat energy according to the recording signal, and the ink is ejected as a liquid ink, or the ink that has already started to solidify when it reaches the recording medium. The use of an ink having a property of being liquefied for the first time by heat energy, such as described above, is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or Japanese Patent Application Laid-Open No. 60-71260, while being held as a liquid or solid substance in a porous sheet concave portion or through hole so as to face the electrothermal converter. It is good also as a form. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

FIG. 7 is a block diagram showing a control configuration of the ink jet recording apparatus according to the present embodiment.

In FIG. 7, reference numeral 24 denotes a control unit for controlling the entire apparatus. The control unit 24 includes a CPU 25 and a CP.
It has a ROM 26 storing a control program and various data executed by the U 25, a RAM 27 used as a work area when the CPU 25 executes various processes, and a RAM 27 for temporarily storing various data. .

As shown in FIG. 7, the recording head 1 is connected to a control unit 24 via a flexible cable 7, and the flexible cable 7 includes a control signal line, an image signal line, and the like from the control unit 24 to the recording head 1. Have been. The output of the ink detection sensor 44 is output to the A / D conversion circuit 2
The CPU 25 is configured to be able to analyze the ink ejection amount according to the A / D converted digital value which is input to the control unit 24 via the control unit 8. Further, the control unit 24 controls the carriage motor 30 via the motor drive circuit 20, the rotation of the transport motor 22 via the motor drive circuit 21, and the rotation of the reading motor 40 via the motor drive circuit 41.

Further, the control unit 24 is a printer / printer that receives a recording command and recording data from the external computer 56.
The interface 57 and the like are connected. Control unit 2
4 is a line control circuit 43 for transmitting data from the public telephone line 42
Receive through. The control unit 24 is connected to an operation panel 58 on which the apparatus user performs various operations and instructions.
The operation panel 58 is provided with a display unit (LCD) 59 for displaying various messages to the operator. Reference numeral 48 denotes a reference clock described later.

FIG. 8 is a block diagram showing an electric configuration of the ink remaining amount detecting sensor. In FIG. 8, reference numeral 44a denotes an infrared LED which is a light emitting element, 44b denotes a phototransistor which is a light receiving element for receiving the infrared light, and 46 denotes a predetermined reference voltage (Vre
f) a comparator to be compared with 47)
It is a pulse width counting unit that measures the duration (pulse width) of the pulse output from. The pulse width counting unit 47 uses the pulse width of the input clock (reference clock) as a reference pulse width, counts how many cycles of the reference clock the duration of the pulse output from the comparator 46 is, and counts the count. The value is output to an internal register of the pulse width counting unit.

When no ink is ejected from the recording head 1, there is nothing to block the infrared light from the infrared LED, which is a light emitting element. H) A level signal is input. On the other hand, when ink is ejected from the recording head 1, the ejected ink blocks the infrared light from the infrared LED, so that the output level from the phototransistor 44b gradually decreases. When the output level falls below the reference voltage (Vref) input to the comparator 46, the output from the comparator 46 to the pulse width counting unit 47 is inverted. Thereafter, when the ejection of the ink from the recording head 1 is completed, the output from the phototransistor 44b goes to the high (H) level again. When the output exceeds the reference voltage (Vref) input to the comparator 46, the output from the comparator 46 The output to the pulse width counting unit 47 is inverted again.

In this manner, a pulse having a pulse width equal to the time during which the phototransistor 44b detects the ejected ink is input to the pulse width counting section 47. As described above, the pulse width is measured using the reference clock and stored in the RAM 27 of the control unit 24. This count value is read by the CPU 25 of the control unit 24 after the end of ink ejection, and is used for determining the presence or absence of ink.

As shown in FIGS. 4 and 5, the conventional ink detection sensor 44 'includes an upper cover 44c' and a lower cover 44d ', which are exterior materials, a light emitting element 44a', a light receiving element 44b ',
It comprises a board 44f 'on which a connector 44e' is mounted. Slits 45 'are provided on the light emitting element 44a' side and the light receiving element 44b 'side in order to increase the light blocking rate of the optical axis by ink, and the distance between the light emitting element 44a' and the light receiving element 44b 'is reduced as much as possible. Increases accuracy. The ink ejected by the ejection for detecting the presence or absence of the ink is ejected so as to pass between the light emitting element 44a 'and the light receiving element 44b', so that the ink lands near the joint 44g 'between the upper cover 44c' and the lower cover 44d '. Since the ink is liquid, it penetrates into the sensor by capillary action. If the penetrated ink adheres to the pattern on the substrate 44f ', a problem such as a short circuit of the pattern may occur because the ink is a conductor.

FIG. 6 shows the ink detection sensor 44 of this embodiment.
It is a perspective view of. The ink detection sensor 44 includes an upper cover 44
c, the upper cover 44c and the lower cover 44 as shown in FIG.
The shape is such that the joint 44g of d is covered and hidden.
As a result, the landed ink does not permeate into the sensor unlike the conventional example.

In this embodiment, the ink is prevented from penetrating by devising the shape of the cover. However, the same effect can be obtained by closing the joint of the cover with a sealing material or the like.

In addition to the above, the recording apparatus according to the present invention may be provided not only as an image output terminal of an information processing apparatus such as a computer but also integrally or separately, a copying apparatus combined with a reader, etc. It may take the form of a facsimile machine having functions.

Further, the present invention may be applied to a system constituted by a plurality of devices, or may be applied to an apparatus constituted by a single device. Needless to say, the present invention can be applied to a case where the present invention is implemented by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium to a system or an apparatus, the system or the apparatus operates in a predetermined manner.

[0054]

As described above, according to the present invention, it is possible to prevent the ink from penetrating into the detecting means due to the landing of the ink. Therefore, the distance between the light emitting / receiving elements of the detecting means is reduced. There is an effect that it is possible to secure a sufficient amount of light between light emission and light reception and improve detection accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a facsimile apparatus.

FIG. 2 is a perspective view illustrating a configuration of an inkjet recording unit.

FIG. 3 is a perspective view illustrating a configuration of a recording head.

FIG. 4 is a perspective view of a conventional photointerrupter sensor.

FIG. 5 is a schematic configuration diagram of a conventional photointerrupter sensor.

FIG. 6 is a perspective view of a photointerrupter sensor according to the present invention.

FIG. 7 is a block diagram of a control configuration according to the present invention.

FIG. 8 is a block diagram of an electric configuration of a photointerrupter sensor.

[Explanation of symbols]

 1 recording head 2 carriage 44 ink detection sensor

Claims (4)

[Claims] An ink jet recording apparatus for performing recording using an ink jet head for discharging ink is provided at a predetermined position within a moving area of the ink jet head, and detects a detection signal of ink discharged from the ink jet head. An ink detection sensor which outputs the following. The ink detection sensor, wherein the ink detection sensor has a shape such that the ink does not penetrate into the sensor from a portion where the ink discharged from the inkjet head lands. 2. The ink detection sensor has a light emitting element and a light receiving element, and changes in light reaching the light receiving element by ink ejected between the light emitting element and the light receiving element from the inkjet head. The ink detection sensor according to claim 1, wherein the detection signal is output according to the following. 3. The ink detection sensor according to claim 1, wherein a shape of a portion of the ink detection sensor where ink ejected from the ink jet head lands has a shape that prevents ink from entering a joint of an exterior material of the sensor. The ink detection sensor according to claim 1. 4. A shape of the ink detection sensor for preventing ink from entering from a seam of the exterior material is a rib formed integrally with the exterior material of the sensor, and the rib is formed when the exterior material is combined. The ink detection sensor according to claim 3, wherein the ink detection sensor is formed so as to cover the joint.