JPH07117441B2 - Liquid level detection means - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid level detecting means used for detecting the liquid level of an ink container or the like by means of a photo interrupter.

[Prior art]

Inkjet storage devices or devices that record images with ink, such as an XY recorder, are equipped with ink tanks (main tank, sub tank, etc.) and waste ink tanks. When the level is reached, the desired processing operation is performed.

For example, in an ink sub-tank in an ink jet recording apparatus, when the ink remaining amount becomes low, the ink runs out, so when the liquid level drops, an ink suction operation is performed or the ink cartridge (main tank) is replaced. Processing is required.

By the way, as a liquid level detecting method in a conventional ink tank or the like, there is a method of using an electrical sensor utilizing the conductivity of ink or an optical sensor utilizing the opaque color of ink, but the transparency depends on the ink color. Different,
Moreover, it is difficult to distinguish the ink adhering to the wall surface from the actual liquid surface, and further, since the adhered ink is difficult to drop, the level detection is unstable and tends to be inaccurate.

Furthermore, when the float for detection comes into close contact with the float, the followability of the float depending on the change in the liquid amount deteriorates, resulting in malfunction.

However, if the distance between the inner surface of the ink container and the float is increased to improve this point, the float becomes relatively freely movable, and as a result, the posture inside the float container becomes unstable and the accurate liquid level There is a problem that detection becomes difficult.

〔Purpose〕

An object of the present invention is to solve the problems of the prior art as described above, and by using a photo interrupter, a float for liquid level detection capable of accurately detecting the liquid level regardless of the color of liquid such as ink color. Is to provide.

〔Overview〕

The present invention comprises a container that is made of a light-transmissive member and that stores a liquid, and a shielding member that is housed in the container and that is made of a light-impermeable thin plate and that is joined to a buoyancy material, and that the container has the surface thereof. A float provided with a protruding member capable of contacting the inner surface of the container, and a detection unit configured to include a light emitting unit and a light receiving unit, the detecting unit detecting a light blocking state by the float that is displaced according to the amount of liquid in the container. The above-mentioned object is achieved by the characteristic liquid level detecting means.

In this case, it is preferable to use infrared light that is transparent to liquids of various colors and plastics as the light beam of the photo interrupter, and to form the tank with plastics.

Further, it is preferable to use polymethylpentene having a particularly small specific gravity as the plastic material of the float to increase the buoyancy.

〔Example〕

 The present invention will be specifically described below with reference to the drawings.

1 is a plane view of a main part of an ink jet recording apparatus provided with an ink remaining amount detecting device using a liquid level detecting float according to the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. Show.

In FIG. 1, a recording sheet 2 such as paper or a thin plastic plate is backed up by a platen 1, guide shafts 3, 3 are installed in front of the recording sheet 2, and a carriage 4 reciprocates in the direction of arrow A along the guide shaft. A recording head (inkjet head) 5 is mounted.

A plurality of ink ejection ports are formed on the front surface of the recording head 5, and each ink ejection port is driven based on print data, and in synchronization with this, the carriage 4 performs main scanning to perform recording.

Reference numeral 6 indicates a main body such as a frame or a chassis of the recording apparatus, and the guide shafts 3, 3 and the shaft of the platen 1 are supported by the main body. The platen 1 shown in the drawing has a roller shape and also serves as a sheet conveying roller.

A home position HP of the carriage 4 is set on the left side outside the range of the platen 1, and a recovery device 7 for capping the recording head 5 during non-printing and sucking ink to perform a recovery operation is provided at this home position. .

The carriage 4 is equipped with a sub-tank 9 which is connected to the recording head 5 via a tube 8 and supplies ink to the recording head. The sub tank 9 is connected to an ink cartridge (main tank) 10 mounted on the main body 6 side via a flexible ink supply tube 11 that absorbs movement of the carriage 4.

On the body 6 side, they were installed facing each other at a predetermined interval.
A photo interrupter including a light emitting element 12 such as an LED and a light receiving element 13 such as a photoelectric element is provided.

A carriage 4 is provided between the photo interrupters 12 and 13.
The ink remaining amount detecting portion of the sub-tank 9 enters so as to interrupt the photo interrupter when passing through the vicinity of the home position HP.

FIG. 2 shows a cross section of the ink remaining amount detecting portion, and FIG. 3 shows a liquid level detecting float.

In FIG. 1 and FIG. 2, a float 14 is housed in the ink remaining amount detecting portion 9A of the sub-tank 9 so as to be movable up and down, and a photo composed of the light emitting element 12 and the light receiving element 13 is sandwiched between the floats. An interrupter is installed. The line X in FIG. 2 indicates the optical axis.

That is, when the ink level 20 in the sub tank 9 is above a predetermined level, the float 14 is held at the upper limit position where it comes into contact with the stopper 21 on the inner surface of the sub tank 9 due to its buoyancy, and the remaining amount of ink falls below a predetermined value. Float on reaching 14
Moves away from the stopper 21.

This sub-tank 9 and ink are photo interrupters.
It is made of a material that allows transmission of 12, 13 light (eg infrared light).

However, as shown in FIG. 3, the float 14 for detecting the liquid surface has a structure in which a shield plate 22 made of a light impermeable thin plate such as stainless steel is sandwiched and joined by a light permeable buoyancy material 23 such as plastic. Have.

Further, by providing the shield plate 22 in the lower half portion of the float 14 as shown in the drawing, the center of gravity of the float is set to the lower side, thereby improving the stability during vertical movement.

It should be noted that in the illustrated example, the upward protruding portions 22 are provided on both sides of the shield plate 22.
A and 22A are formed. This protrusion 22A, 22A is a float
It can be used for the purpose of taking out a pulse signal at a predetermined vertical position (predetermined level) of 14, but it may be omitted if only the remaining ink amount in the sub tank 9 is detected.

The plastic material (buoyant body) 23 forming the float 14 is preferably as light as possible, for example, polymethylpentene having a small specific gravity is preferably used.

Further, a projection 24 that locally contacts the inner surface of the sub tank 9 is formed at a desired position on the surface of the float 14 to prevent the float 14 from coming into close contact with the inner surface of the sub tank and causing malfunction.

Furthermore, as the light rays of the photo interrupters 12 and 13,
It is preferable to use infrared light which is transparent to inks of various colors and plastic materials.

The carriage 4 (or recording head 5) is used to detect the remaining ink
Is sufficient when the vehicle is at a specific position. In the illustrated example, the carriage 4 is at or near the home position HP, and the vertical movement path of the float 14 is the photo interrupter.
It is detected when the optical axes X of 12 and 13 are aligned.

At the time of detection, if the ink amount in the sub tank 9 is sufficient and the liquid surface 20 is above a predetermined level, as shown in FIG.
14 is at the upper position, and the optical axis X of the photo interrupters 12 and 13 is blocked by the shield plate 22.

On the other hand, when the remaining amount of ink is less than the predetermined amount and the ink runs out, the float 14 is located at the lower position, and therefore the shield plate 22 is located below the optical axis X, so that the light from the photo interrupters 12 and 13 is emitted. The light is transmitted and the light receiving element 13 is illuminated.

In this way, it is possible to photoelectrically detect the ink liquid surface, which is a kind of liquid surface.

According to the embodiment described above, the float 14 configured by joining the shield plate 22 to the plastic material 23 is used, and the upper and lower positions thereof are detected by the photo interrupters 12 and 13 of infrared light. The liquid level (remaining amount of ink) can be accurately and quickly detected without being affected by the color or property of the liquid.

Further, since the float 14 is composed of the shield plate 22 made of stainless steel and the plastic material 23 having a low density such as polymethylpentene, it is possible to secure sufficient buoyancy by itself, and further, the shield plate 22 is provided with the lower half part. Since it was joined to, the center of gravity of the float 14 could be stably moved up and down, and the detection accuracy could be improved.

Furthermore, since the upper and lower positions of the float 14 are restricted by the stopper 21, the buoyancy of the float can be substantially increased, and at the same time, the float is kept below the liquid surface to prevent the shake. Became possible.

Further, by providing the protrusions 24 on the surface of the float, the float is prevented from adhering to stabilize the posture of the float in the container, and the liquid corresponding to the change in the liquid amount in the gap between the float and the ink container inner surface is formed. The movement of the float was performed, and the followability with the liquid surface of the float was improved.

In the above embodiments, the case where the float 14 is used for detecting the ink remaining amount of the sub tank 9 of the injet recording apparatus has been described. However, the liquid level detecting float according to the present invention is used in a container (tank) having a constant shape. As long as it is a device that detects the liquid level of the liquid stored in the liquid by a photo interrupter, it can be widely applied regardless of the kind field.

〔effect〕

As is clear from the above description, according to the liquid level detection means of the present invention, a shield made of a light-transmissive member and containing a liquid, and a light-impermeable thin plate housed in the container. The member is joined to a buoyant material, and the float is provided with a protruding member capable of contacting the inner surface of the container on the surface, a light emitting unit and a light receiving unit, and is displaced according to the amount of liquid in the container. A liquid level detecting means that can detect the liquid level in the container accurately and quickly because the float can move in a stable state according to the liquid level, since the detecting means for detecting the light blocking state by the float is configured. Will be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a main portion of an in jet recording apparatus equipped with a liquid level detecting means according to an embodiment of the present invention, and FIG.
FIG. 3 is a partial cross-sectional view taken along the line II-II in the figure, and FIG. 3 is a perspective view of the float for detecting the liquid surface in FIG. 4 ... Carriage, 9 ... Sub tank, 12, 13 ... Photo interrupter, 14 ... Liquid level detection float, 20 ... Liquid level, 22 ... Shield plate, 23 ... Plastic material, X ...
optical axis.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akira Miyagawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigeru Rokubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Koichi Ikeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP 60-2903 (JP, A) JP 61-34424 (JP) , A) Actually opened 58-103333 (JP, U) Actually opened 55-25203 (JP, U) Actually opened 49-19767 (JP, U)

Claims (5)

[Claims] 1. A container made of a light-transmissive member for containing a liquid, and a shielding member, which is housed in the container and made of a light-impermeable thin plate, bonded to a buoyancy material, and has the surface of A float provided with a projecting member capable of coming into contact with the inner surface of the container; and a detection unit configured to include a light emitting unit and a light receiving unit and detecting a light blocking state by the float that is displaced according to the amount of liquid in the container. A liquid level detecting means. 2. The liquid level detecting means according to claim 1, wherein the material of the buoyancy member is polymethylpentene. 3. The light emitted by the light emitting unit is infrared light, according to claim 1 or 2.
Liquid level detection means according to the item. 4. The liquid level detecting means according to claim 1, wherein the float is formed by joining the shielding member to a lower half of the float. 5. The liquid surface according to claim 1, wherein the container has a stopper on an inner surface of the container for regulating an upper limit position of the float. Detection means.