JP2000071470A - Ink tank and recorder employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink tank in which residual ink level can be detected, and a recorder employing it. SOLUTION: When recording is to be performed by using ink tank 7 arranged, on the bottom face thereof, with a plurality of light transmitting triangular prisms 18 (L-S) having different size at least in the varying direction of ink level, the plurality of triangular prisms are irradiated with light at least on the reflective face thereof and ink level in the ink tank 17 is estimated based on the light reflected from each triangular prism reflecting the ink level in the ink tank 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink tank and a recording apparatus using the ink tank, and more particularly to supplying ink to a recording head used for recording by discharging ink onto a recording medium in accordance with an ink jet recording method. And a recording apparatus using the ink tank.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet recording apparatus which performs recording by discharging minute ink droplets from a recording head. Compared with other recording apparatuses, this apparatus has low noise, can perform high-speed recording, can easily perform color recording, and can use recording media such as cloth as well as plain paper for recording. This has the advantage that high-quality recording is possible.

Generally, a recording head of an ink jet recording apparatus has an ejection port (orifice) for ejecting about 1 to 2000 ink droplets, and makes the recording head scan relative to a recording medium. Then, recording is performed on the entire area of the recording medium. In an actual printing operation, the print head is mounted on a carriage, and the carriage is reciprocated along its movement path (the moving direction is referred to as a main scanning direction). The recording medium is transported in a direction perpendicular to the moving direction (the direction is referred to as a sub-scanning direction).

Usually, the recording head is constituted as an ink cartridge integrated with an ink tank for supplying ink to the recording head, and an ink cartridge which is detachable from the carriage is mounted on the carriage. Then, the carriage performs recording by reciprocating the ink cartridge.

Conventionally, a sensor is fixed to the main body of the recording apparatus, the amount of ink remaining in the ink tank is automatically detected by using the movement of a carriage, and a user is determined based on the detection result. Is provided with a means for issuing a warning. For example, as such an ink remaining amount detecting means, there are a means for providing an electrode in an ink tank to measure the electric conductivity between the electrodes and a means for optically detecting a discharged ink droplet. In general, the method using electrodes complicates the structure of the ink tank itself, and therefore, usually, means for optically detecting the remaining amount of ink is often used.

FIG. 8 is a diagram showing an example of the configuration of a conventional ink remaining amount detecting section for optically detecting the remaining ink amount.

In FIG. 8, reference numeral 101 denotes an ink tank;
02 is an optical prism, 103 is a light emitting element such as an infrared LED, 104 is a light receiving element such as a phototransistor, 105 is ink, and 106 is an optical unit incorporating a light emitting element and a light receiving element.

[0008] The ink tank 101 is formed of a translucent plastic-like member having optical transparency, and the ink 1
05 is stored. An optical prism 102 serving as an optical ink detector is formed at the bottom. The optical prism 102 is the ink tank 101
It is molded integrally with a transparent material such as polypropylene.

Now, the ink 105 is stored in the ink tank 101.
When there is no light, the light emitted from the light emitting element 103 is reflected on the boundary surfaces 102A and 102B between the optical prism 102 and the ink 105 and reaches the light receiving element 104. On the other hand, when the ink tank 101 is full of the ink 105, the ink tank 101 itself and the ink 105
, The reflectance at the interfaces 102A and 102B is different from that without the ink 105, and as a result, the light from the light emitting element 103 causes the interfaces 102A and 102B
The amount of light reaching the light receiving element 104 via B decreases.
As described above, it is possible to detect the presence or absence of the ink 105 in the ink tank 101 based on the difference in the amount of light detected by the light receiving element 104.

[0010]

However, in the above conventional example, the boundary surface 1 between the optical prism 102 and the ink 105
Since only the presence or absence of the ink 105 at the position where light is reflected in 02A and 102B can be detected, there is a disadvantage that the amount of the ink 105 remaining in the ink tank 101 cannot be known.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional example, and has as its object to provide an ink tank capable of detecting a remaining ink level in an ink tank and a recording apparatus using the ink tank. .

[0012]

In order to achieve the above object, an ink tank according to the present invention has the following configuration.

That is, an ink tank for storing ink, wherein a plurality of light-transmitting triangular prisms having different sizes at least in a direction in which the ink level of the ink changes is provided on a bottom surface of the ink tank. It has a characteristic ink tank.

Here, the plurality of triangular prisms are arranged in a line in a predetermined direction, and the side surfaces of the plurality of triangular prisms are arranged so as to be perpendicular to the predetermined direction, and the side surfaces are adjacent to each other. It is preferable to be in contact with the side surface of the matching triangular prism.

According to still another aspect of the present invention, there is provided a recording apparatus for performing recording by supplying ink to a recording head which performs recording in accordance with an ink jet system using the ink tank having the above-described configuration, wherein the predetermined direction is the ink tank. Scanning means for mounting and reciprocating the ink cartridge so that the ink cartridge moves in the direction of movement of the ink cartridge in which the ink cartridge is integrated with the recording head; and Optical means for irradiating light to the reflecting surface of each of the plurality of triangular prisms arranged in the moving direction of the cartridge, and receiving the reflected light of the light, and driving the optical means,
Estimating means for estimating the ink level of the ink tank based on the reflected light received by the optical means.

Here, the optical means includes an LED for irradiating infrared light, and a phototransistor for receiving the infrared light and converting the received infrared light into an electric signal.

Here, the optical means preferably includes an LED for irradiating infrared light, and a phototransistor for receiving the infrared light and converting the received infrared light to an electric signal. It is preferable that the LED and the phototransistor are arranged side by side in the transport direction of the recording medium.

The detecting means converts the electric signal converted based on the light reflected by the plurality of triangular prisms and received by the phototransistor into a digital electric signal, and converts the electric signal into a digital electric signal based on the digital electric signal. hand,
The ink level of the ink tank can be estimated.

The recording head may include an electrothermal converter for generating thermal energy to be applied to the ink in order to discharge the ink using the thermal energy.

With the above arrangement, the present invention is applicable to a case where recording is performed using an ink tank provided with a plurality of light-transmitting triangular prisms having different sizes at least in the direction in which the ink level of the ink changes, provided on the bottom portion. An operation is performed to irradiate light to the reflecting surfaces of the plurality of triangular prisms, receive the reflected light, and estimate the ink level of the ink tank based on the received reflected light.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a schematic configuration of a recording apparatus having a recording head for performing recording according to an ink jet system, which is a typical embodiment of the present invention. In this embodiment, as shown in FIG. 1, the recording head 1 is included in an ink cartridge 20 integrally formed with an ink tank 7 for supplying ink to the recording head. Note that an optical prism for detecting the remaining amount of ink is provided on the bottom surface of the ink tank 7.

In FIG. 1, a recording head 1 is mounted on a carriage 2 in a posture for ejecting ink downward in the figure, and ejects ink droplets while moving the carriage 2 along a guide shaft 3 to form recording paper. An image is formed on a recording medium (not shown) as described above. The carriage 2 is moved left and right (reciprocated) via the timing belt 5 by the rotation of the carriage motor 4. An engagement claw 6 is provided on the carriage 2, and is engaged with an engagement hole 7 a of the ink tank, so that the ink tank is fixed to the carriage 2.

When printing for one scan of the print head is completed, the printing operation is interrupted, the printing medium positioned on the platen 8 is conveyed by a predetermined amount by driving the feed motor 9, and then the carriage 2 is moved again by the guide shaft. While moving along 3, the image formation for the next one scan is performed.

On the right side of the apparatus main body, a recovery device 1 for performing a recovery operation for maintaining a good ink discharge state of the recording head 1 is provided.
The apparatus 10 includes a cap 11 for capping the recording head 1, a wiper 12 for wiping the ink ejection surface of the recording head 1, and a device for sucking ink from the ink ejection nozzles of the recording head 1. A suction pump (not shown) and the like are provided.

The driving force of the feed motor 9 for conveying the recording medium is transmitted to the original recording medium conveying mechanism and also to the automatic paper feeder (ASF) 13.

Further, on the side of the recovery device 10, an infrared LE
An optical unit 14 for detecting the remaining amount of ink, comprising a D (light emitting element) 15 and a phototransistor (light receiving element) 16, is provided. The optical unit 14 is mounted on a chassis 17 of the apparatus main body. When the ink cartridge 20 is mounted on the carriage 2 and moves rightward from the position shown in FIG.
0 is located on the optical unit 14. Then, the state of the ink can be detected from the bottom surface of the ink tank 7 by the optical unit 14 (details will be described later).

Next, a control configuration for executing the recording control of the above-described apparatus will be described.

FIG. 2 is a block diagram showing the configuration of the control circuit of the printing apparatus. In the figure showing the control circuit, 170
0 is an interface for inputting a recording signal, 1701 is M
A PU 1702 is a ROM for storing a control program executed by the MPU 1701, and a 1703 is a DRAM for storing various data (such as the print signal and print data supplied to the print head 1). A gate array (G.1704) controls supply of print data to the print head 1.
A. ), The interface 1700, the MPU 170
1. Data transfer control between the RAMs 1703 is also performed. 170
5, a head driver 170 for driving the recording head 1;
Reference numerals 6 and 1707 denote motor drivers for driving the feed motor 9 and the carriage motor 4, respectively.

The operation of the above control configuration will be described. When a recording signal enters the interface 1700, the gate array 17
04 and the MPU 1701 converts the recording signal into recording data for printing. Then, the motor driver 17
06 and 1707 are driven, and the head driver 1
The recording head 1 is driven according to the recording data sent to 705, and recording is performed.

Further, an ink remaining amount detecting unit 25 for detecting the presence or absence of ink in the ink tank 7 integrated with the recording head 1.
Is controlled by the MPU 1701. The details of the remaining ink amount detection unit 25 will be described later.

FIG. 3 is a diagram showing how light from the optical unit is reflected by the optical prism on the bottom surface of the ink tank and returns to the optical unit. In FIG. 3, reference numeral 18 denotes an optical prism in the form of a triangular prism, 19a denotes a prism reflecting surface, 1
9b is a prism side wall, and 19c is a prism bottom surface.

As can be seen from FIG. 3, the prism reflecting surface 1
9a is at an angle of 45 ° in the direction in which the light emitting element 15 and the light receiving element 16 are arranged (the direction of arrow F in FIGS. 1 and 3 and the direction in which the recording paper is conveyed), and the prism side wall 19b is in the carriage moving direction (FIG. The optical prism 18 is disposed so as to be perpendicular to the direction indicated by the arrow CR in FIG.

FIG. 4 is a block diagram showing a detailed configuration of the ink remaining amount detecting section 25.

In the configuration shown in FIG.
Controller 32 based on the control signal from
Outputs a pulse signal having a predetermined duty (DUTY) ratio (%) to the LED drive circuit 30, drives the light emitting element 15 included in the optical unit 14 according to the duty ratio, and outputs infrared light to the ink tank 7. Irradiate the bottom.

The infrared light is reflected by a predetermined amount on the prism reflecting surface 19a of the optical prism 18 at the bottom of the ink tank 7, and returns to the light receiving element 16 constituting the optical unit 14. The light receiving element 16 as a phototransistor converts the received light into an electric signal, and outputs the electric signal to a low-pass filter (LPF) 31. Low-pass filter (L
The PF 31 cuts high-frequency noise out of the electric signals input from the light receiving element 16 and sends only the signal with a low frequency to the controller 32. The controller 32 A / D converts the signal of the low-pass filter (LPF) 31 and converts the signal into a digital signal. Then, the converted value is the MPU 170
Transferred to 1.

FIG. 5 is a perspective view showing the arrangement of a plurality of optical prisms provided in the ink tank 7.

In this embodiment, three optical prisms 18S, 18M, and 18L having different sizes are arranged inside the ink tank 7 in the carriage movement direction (the direction of arrow CR), and the largest optical prism 18L is provided. The side surface forms a part of the side surface of the ink tank 7.

FIG. 6 is a sectional view of the ink tank 7 shown in FIG. 5 when viewed from the direction of arrow F (see FIG. 1), the relative positional relationship between the ink tank 7 and the optical unit 14, and the light receiving element. It is a figure which shows the relationship with 16 light reception amounts.

FIG. 7 is a sectional view of the ink tank 7 shown in FIG. 5 when viewed from the direction of arrow CR. As can be seen from FIG. 7, the three optical prisms 18S, 18M, and 18L having different sizes have the bases of the triangular prisms at different positions but at a common place, and the light emitted from the light emitting element 15 is reflected by the oblique sides. The light is reflected and reaches the light receiving element 16.

A change in the amount of light received by the light receiving element 16 according to the remaining amount of ink in the ink tank 7 will be described below with reference to FIGS.

First, when the carriage 2 on which the ink tank 7 is mounted moves in the direction indicated by the arrow CR as shown in FIG. 6, the light emitted from the light emitting element 15 emits the optical prisms 18L, 18M, 18S according to the movement of the carriage 2. Are sequentially incident.

Here, assuming that there is no ink in the ink tank 7, when the optical prism 18L is located directly above the optical unit 14, the light emitted from the light emitting element 15 is emitted twice on the slope of the optical prism 18L. The light is reflected and follows a path 110 indicated by a two-dot chain line to reach the light receiving element 16. Next, when the optical prism 18M is positioned directly above the optical unit 14, the light emitted from the light emitting element 15
The light is reflected twice on the slope of L and follows the path 111 indicated by the dashed line to reach the light receiving element 16. Lastly, when the optical prism 18S is located directly above the optical unit 14, the light emitted from the light emitting element 15 is reflected twice on the slope of the optical prism 18L, follows the path 112 shown by the solid line, and travels to the light receiving element 16. Reach.

Next, a change in the amount of light detected by the light receiving element 16 when the amount of the ink 7I in the ink tank 7 changes will be described.

(1) The ink level of the ink tank 7 (I
L) When IL ≧ a In this case, the amount of light received by the light receiving element 16 is constant irrespective of the relative position between the ink tank and the optical unit, as shown by the thick line in FIG. That is, the light receiving element 16 simply receives the background light (Iback).

(2) The ink level of the ink tank 7 (I
L) is b ≦ IL <a In this case, the amount of light received by the light receiving element 16 has a peak value only when the optical prism 18L is located directly above the optical unit 14 as shown by a solid line in FIG. Show. That is, only the reflection surface of the optical prism 18L is exposed above the ink.

(3) The ink level of the ink tank 7 (I
L) is c ≦ IL <b In this case, the amount of light received by the light receiving element 16 is determined when the optical prism 18L and the optical prism 18M are located directly above the optical unit 14 as shown by the broken line in FIG. Shows the peak value. Therefore, the time during which the peak value is shown is slightly longer than in the case of (2). That is, the reflection surfaces of the optical prisms 18L and 18M are exposed above the ink.

(4) The ink level of the ink tank 7 (I
L) When IL <c In this case, the amount of light received by the light receiving element 16 is gentle when the optical prisms 18L, 18M, and 18S are located directly above the optical unit 14, as indicated by the dashed line in FIG. The peak value. That is, the optical prisms 18L, 18M, 1
The 8S reflection surface is exposed above the ink.

Therefore, according to the embodiment described above, the light receiving characteristic of the light receiving element 16 changes depending on the difference in the amount of remaining ink in the ink tank 7, and the controller 32 and the MPU 1701 control the light receiving amount based on the light receiving characteristic. By detecting the timing at which the peak value is taken and how long the peak value continues, it is possible to determine which optical prism is receiving the reflected light, and according to the determination result, determine the ink level in the ink tank. Can be estimated in four steps as described above.

The optical prism in the ink tank has a simple structure and is manufactured integrally with the ink tank, so that there is an advantage that the manufacturing cost is low.

In the above embodiment, three optical prisms are provided on the bottom surface of the ink tank, and the respective prisms are in contact with the side surfaces. However, the present invention is not limited to this. For example, the number and arrangement of the optical prisms may be a number and arrangement method other than the above-described embodiment, or a configuration may be employed in which the side wall of each optical prism is in contact with the ink.

It is also possible to notify the connected device (for example, a host computer) of the detected remaining amount of ink via the interface 1700, or to turn on an LED on a display panel provided in the recording apparatus. , L
It is also possible to indicate the remaining amount of ink by displaying a message on a CD or the like.

In the above embodiment, the description has been made assuming that the liquid droplets ejected from the recording head are ink and the liquid stored in the ink tank is ink. It is not limited. For example, an ink tank may contain a processing liquid discharged to a recording medium in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

The above-described embodiment is particularly provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink even in an ink jet recording system. By using a method in which a change in the state of the ink is caused by energy, 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 can be applied to both the so-called on-demand type and the continuous type.
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the film boiling to the electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. 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 the 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 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 a heat acting surface is arranged in a bent region, is also included in the present invention. In addition, for multiple electrothermal transducers,
JP-A-59-123670 which discloses a configuration in which a common slot is used as a discharge part of an electrothermal transducer, and JP-A-59-123670 which discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge part. A configuration based on 138461 may be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition to the cartridge type recording head in which the ink tank is provided integrally with the recording head itself described in the above embodiment, the recording head is electrically connected to the apparatus main body by being mounted on the apparatus main body. A replaceable chip-type recording head, which enables a simple connection and supply of ink from the apparatus main body, may be used.

It is preferable to add recovery means for the print head, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, 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, but may be a single recording head or a combination of a plurality of recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

In the above-described embodiment, the description has been made on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, the ink that softens or liquefies at room temperature is used. Or, in the ink jet method, generally, the temperature of the ink itself is controlled 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.
It is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent temperature rise due to thermal energy as energy for changing the state of the ink from the solid state to the liquid state,
Alternatively, in order to prevent evaporation of the ink, an ink which solidifies in a standing state and liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching 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, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. 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, as a form of the recording apparatus according to the present invention, in addition to an image output terminal of an information processing apparatus such as a computer which is provided integrally or separately, a copying apparatus combined with a reader or the like, It may take the form of a facsimile machine having functions.

Even if the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), a device including one device (for example, a copying machine, a facsimile machine) Etc.).

[0066]

As described above, according to the present invention, recording is performed using an ink tank provided with a plurality of light-transmitting triangular prisms having different sizes at least in the direction in which the ink level of the ink changes. When performing, the reflection surface of each of the plurality of triangular prisms is irradiated with light, and the reflected light is received, so that the received reflected light reflects the ink level of the ink tank. There is an effect that the ink level of the ink tank can be estimated from the reflected light.

[0067]

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a recording apparatus including a recording head that performs recording according to an inkjet method, which is a typical embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control circuit of the printing apparatus.

FIG. 3 is a diagram illustrating a state in which light from an optical unit is reflected by an optical prism on a bottom surface of an ink tank and returns to the optical unit.

FIG. 4 is a block diagram illustrating a detailed configuration of an ink remaining amount detection unit.

FIG. 5 is a perspective view showing an arrangement of a plurality of optical prisms provided in an ink tank 7.

6 shows a cross section of the ink tank when the ink tank 7 shown in FIG. 5 is viewed from the direction of arrow F, and the relationship between the relative positional relationship between the ink tank 7 and the optical unit 14 and the amount of light received by the light receiving element 16. FIG.

FIG. 7 is a sectional view of the ink tank when the ink tank 7 shown in FIG. 5 is viewed from the direction of arrow CR.

FIG. 8 is a diagram illustrating a configuration example of a conventional ink remaining amount detection unit that optically detects the remaining ink amount.

[Description of Signs] 1 Recording head 2 Carriage 3 Guide shaft 4 Carriage motor 5 Timing belt 6 Engagement claw 7 Ink tank 7I Ink 8 Platen 9 Feed motor 10 Recovery device 11 Cap 12 Wiper 13 ASF 14 Optical unit 15 Light emitting element 16 Light receiving Element 17 Chassis 18, 18L, 18M, 18S Optical prism 19a Prism reflecting surface 19b Prism side wall 20 Ink cartridge 30 LED drive circuit 31 Low pass filter (LPF) 32 Controller

Claims (7)

[Claims] 1. An ink tank for storing ink, wherein a plurality of light-transmitting triangular prisms having different sizes at least in a direction in which the ink level of the ink changes is provided on a bottom surface of the ink tank. An ink tank characterized by the following. 2. The plurality of triangular prisms are arranged in a row in a predetermined direction, and side surfaces of the plurality of triangular prisms are arranged so as to be perpendicular to the predetermined direction, and the side surfaces are adjacent to each other. 2. The ink tank according to claim 1, wherein the side surfaces of the triangular prism are in contact with each other. 3. A recording apparatus which performs recording by supplying ink to a recording head which performs recording in accordance with an ink-jet method using the ink tank according to claim 2, wherein the predetermined direction is the same as that of the ink tank. Scanning means for mounting the ink cartridge and reciprocating the ink cartridge so as to be in the direction of movement of the ink cartridge integrated with the head; and
An optical unit that irradiates light to a reflection surface of each of the plurality of triangular prisms arranged in the moving direction of the ink cartridge and receives reflected light of the light; and drives the optical unit, and receives light by the optical unit. A recording unit that estimates an ink level of the ink tank based on the reflected light. 4. The optical device according to claim 1, wherein the optical unit includes an LED that emits infrared light, and a phototransistor that receives the infrared light and converts the received infrared light into an electric signal. Item 4. The recording device according to Item 3. 5. The recording apparatus according to claim 4, wherein the LED and the phototransistor are arranged side by side in a transport direction of the recording medium. 6. The digital electric signal, wherein the estimating means converts an electric signal converted on the basis of light reflected by each of the plurality of triangular prisms and received by the phototransistor into a digital electric signal. 5. The recording apparatus according to claim 4, wherein an ink level of the ink tank is estimated based on the following. 7. The recording head according to claim 3, wherein the recording head includes an electrothermal converter for generating thermal energy to be applied to the ink in order to discharge the ink using thermal energy. The recording device according to any one of the preceding claims.