JPH11230817A - Liquid level detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detecting device wherein adhesion between a float and a float top part due to crystallization of process liquid, etc., is less, malfunction is eliminated, and excellent in responsibility and follow up ability of vertical movement of liquid level as well as in liquid level detection precision. SOLUTION: A long, in vertical direction, switch-incorporating member 2 with a float stop part 6 provided at its upper part, and a magnet-incorporated float 3 which vertically moves along the switch-incorporating member following changes in liquid level, are provided, and the upper surface of the float 3 touches the float stop part 6 facing the upper part by a small touching area. Thus, the float easily detaches itself from the float stop part. Once the float and the float stop part are separated, a crystallization part easily dissolves in a process liquid, so no float buoyancy changes. Thus, a liquid level detecting device with less float malfunction, while excellent in follow up ability of a float to the vertical movement of liquid level is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting device, and more particularly, to a liquid level detecting apparatus, in which the float is hardly fixed to a float stop due to crystallization of a processing liquid, the malfunction is small, and the liquid level moves up and down. Excellent responsiveness and follow-up to
The present invention relates to a liquid level detection device having excellent liquid level detection accuracy.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a float switch conventionally used as a liquid level detecting device. Guide pipe 902 with built-in reed switch 901 and magnet 90
A float switch is used in combination with a float 903 having a ring-shaped cross section incorporating 4. The float 903 is fitted around the guide pipe 902 and moves up and down along the guide pipe 902 in response to the rise and fall of the liquid level.
The switch operation is performed by opening and closing the contact of the reed switch 901 by the magnet 904 built in the 03. Usually, an enlarged portion 906 for defining the upper limit of the movement of the float 903 is provided above the guide pipe 902, and a stopper 905 for defining the lower limit of the movement of the float 903 is provided at the lower end of the guide pipe 902. Is provided. Enlarged part 906 and stopper
905 prevents the float 903 from falling off the guide pipe 902.

In the conventional liquid level detecting device, since the lower surface of the enlarged diameter portion 906 and the upper surface of the float 903 are both flat, the photographic processing solution accumulated on the upper surface of the float is evaporated (or dried).
Due to dripping or crystallization, the lower surface of the enlarged diameter portion 906 of the guide pipe and the upper surface of the float 903 may be fixed. The photographic processing solutions (including replenishers and waste liquids) used in the processing tanks of photographic developing machines are viscous and are liable to crystallize due to evaporation. is there.

[0004] As a result of the sticking by the processing liquid as described above, the conventional liquid level detecting device has the following problems: (1)
The float may malfunction, (2) the float level of the float changes, and the liquid level detection accuracy decreases, and (3) the float operation is slow, and the float follows the vertical movement of the liquid level. And responsiveness is reduced. Therefore, in the conventional liquid level detecting device, it is necessary to frequently perform inspection, cleaning, and adjustment for maintenance.

As described above, there is little sticking between the float and the float stop due to crystallization or the like of the processing solution, there is little malfunction, excellent responsiveness and followability to liquid level up and down, and liquid level detection. There is a demand for a liquid level detection device having excellent accuracy.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to minimize the sticking due to the crystallization of a processing solution and the like.
It is an object of the present invention to provide a liquid level detecting device which is less erroneous, has excellent responsiveness and followability to liquid level up and down, and has excellent liquid level detecting accuracy.

[0007]

According to the present invention, there is provided a liquid level detecting device including a vertically long switch built-in member provided with a float stop at an upper portion, and a switch built-in member along the switch built-in member as the liquid level changes. A magnet built-in float that moves up and down is provided, and the upper surface of the float and the float stop facing the upper surface come into contact with a small contact area.

In a preferred embodiment, the upper portion of the float has a tapered shape.

In a preferred embodiment, the switch built-in member has an immersion portion having a circular cross section in which the switch is built, and a float stop formed above the immersion portion and having a larger diameter than the immersion portion. A projection is provided on the lower surface of the float stop.

[0010] In a preferred embodiment, the projection includes at least one ridge or columnar projection.

The operation of the present invention will be described below.

According to the present invention, since the upper surface of the float and the float stop facing the upper surface come into contact with a small contact area, the float weight per unit area at the contact portion increases. Therefore, even if the processing liquid evaporates and crystallizes between the float and the float stop,
Since the area of the crystallized contact portion is small, the float tends to drop due to its own weight compared to the force for fixing the float to the float stop due to crystallization. Easily leave the department. Once the float is separated from the float stop, the crystallized portion easily dissolves in the processing solution, and the buoyancy of the float does not change. Therefore, a liquid level detecting device with less malfunction of the float and excellent in the followability and responsiveness of the float to the vertical movement of the liquid level can be obtained.

In a preferred embodiment, the float is
The upper part has a tapered shape. As a result, not only is the contact area between the upper surface of the float and the float stop portion reduced, but also the processing liquid drops along the tapered surface, so that the accumulation of the processing liquid (eg, developer) on the upper surface of the float is also prevented. You. As a result, the fixation between the float stop and the upper surface of the float is extremely effectively prevented, so that a liquid level detecting device with less malfunction and excellent responsiveness and followability to the liquid level up and down can be obtained. Furthermore, in such a liquid level detecting device, the processing liquid does not accumulate on the upper surface of the float, so that the buoyancy of the float does not change, and as a result, the liquid level detecting accuracy is excellent.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic sectional view of a liquid level detecting device according to a preferred embodiment of the present invention. This liquid level detector 10
Numeral 0 has a vertically long switch built-in member (for example, casing 2) in which a reed switch 1 is built, and a ring-shaped float 3 in which a magnet 4 is built. The casing 2 has an immersion part 2 ′ having a circular cross section in which the reed switch 1 is built, and a float stop part 6 formed above the immersion part 2 ′ and having a larger diameter than the immersion part. The casing 2 is typically cylindrical as shown in FIG.
The cross-sectional shape may be a polygon (for example, a triangle, a square, a pentagon, a hexagon, a heptagon, an octagon). The float 3 is externally fitted to the casing 2 (immersion part 2 '). As shown in FIG. 2, when the casing 2 is cylindrical, the inner diameter of the hole of the float 3 is slightly larger than the outer diameter of the casing 2, and a gap is defined between the float 3 and the casing 2. . Accordingly, the float 3 moves up and down along the outer surface of the casing 2 by its own weight (or buoyancy) in response to the rise or fall of the liquid level, and the magnet 4 incorporated in the float 3 opens and closes the contact of the reed switch 1. Then, a switch operation is performed to detect the liquid level. Similarly, when the sectional shape of the casing 2 is a polygon, a small gap is defined between the float 3 and the casing 2 so that the float 3 can move up and down along the casing 2 by its own weight.

A stopper 5 is provided near the lower end of the casing 2. For example, the stopper 5 is shown in FIG.
As shown in FIG. 1, a ring made of a C-shaped elastic plastic piece fitted in a groove 10 provided near the lower end of the casing 2. When the liquid level falls below the lower end of the casing 2 by the stopper 5, the casing 2 of the float 3
Falling from the lower end is prevented.

In the upper part of the casing 2, there is provided a float stop 6 for preventing the float 3 from moving excessively upward. The upper surface of the float 3 and the float stop 6 facing the upper surface come into contact with a small contact area. In the present specification, "contacting with a small contact area" means that flat surfaces do not contact each other, for example, point-like contact, linear contact, small-surface contact, and Include combinations. Since the upper surface of the float 3 and the float stop 6 facing the upper surface come into contact with a small contact area, the float weight per unit contact area increases.
Therefore, even if the processing liquid evaporates and crystallizes between the float 3 and the float stop 6, the float 3 is easily separated from the float stop 6 by its own weight because the area of the crystallized portion is small. . Once the float is separated from the float stop, the crystallized portion easily dissolves in the processing liquid, so that the buoyancy of the float 3 does not change. Therefore, a liquid level detecting device with less malfunction of the float and excellent in the followability and responsiveness of the float to the vertical movement of the liquid level can be obtained.

A specific example for achieving contact with a small contact area will be described. For example, as shown in FIG. 1, the float stop portion 6 includes an enlarged portion 7 of the casing 2 and the enlarged portion 7.
And a projection 8 provided on the lower surface of the. For example, as shown in FIG. 2, the protrusion 8 includes at least one ridge 8 ′ that protrudes downward from the flat lower surface of the enlarged diameter portion 7 and extends toward the outside of the enlarged diameter portion 7. The number of the ridges 8 'is not particularly limited as long as the upper surface of the float 3 and the float stop 6 facing the upper surface come into contact with a small contact area. The number of the ridges 8 'is typically 3 to 6, preferably 3 to 4 (FIG. 2 shows a case where the number of the ridges is 4).

For example, as shown in FIG.
Has a columnar shape projecting downward from the lower surface of the enlarged diameter portion 7 (for example,
(In the illustrated example, a columnar shape, a prismatic shape; a columnar shape). The number of the columnar protrusions 8 ″ also has a small contact area between the upper surface of the float 3 and the float stop 6 facing the upper surface. There is no particular limitation as far as it is concerned. The number of the columnar projections 8 ″ is typically 3 to 6, preferably 3 to 4 (FIG. 4 shows a case where the number of the columnar projections is 4). The projection 8 ″ is provided on the lower surface of the enlarged diameter portion 7 near the outer periphery of the casing 2. The shape of the tip of the columnar projection 8 ″ is
It may be rounded, sharp at an acute angle, or flat. Preferably, the shape of the tip of the columnar projection 8 ″ is rounded or sharply pointed. This is to minimize the contact area with the float 3.

As long as the upper surface of the float 3 and the float stop 6 facing the upper surface come into contact with a small contact area, the above-mentioned projection 8 is provided on the upper surface of the float 3 as shown in FIG. Is also good.

Alternatively, as shown in FIGS. 6 and 7,
The float stop 6 includes at least one blade 9 provided on the outer peripheral portion of the casing 2 and extending toward the outside of the casing 2. The number of the blades 9 is also not particularly limited as long as the upper surface of the float 3 and the float stop 6 facing the upper surface come into contact with a small contact area. The number of the blades 9 is typically 3 to 6, preferably 3 to 4 (FIG. 6).
Indicates that the number of blades is four). The vertical length of the blade is not particularly limited.

Preferably, the float 3 has a tapered portion 11 at the top, as shown in FIG. 1 and more particularly in FIG.
Having. The shape and the inclination angle of the taper of the taper portion 11 are not particularly limited as long as there is no obstacle to the treatment liquid falling on the tapered surface. Preferably, as shown in FIG. 8, the tapered portion 11 has a tapered shape inclined toward the outside of the float 3. Further, the tapered portion 11 may have a flat portion 12 near the innermost part of the float 3. By providing the flat portion 12, the float 3 can be positioned more accurately.

The liquid level detecting device of the present invention is suitably used for a processing liquid tank, a replenishing liquid tank, a water refilling tank, a waste liquid tank, etc. of a photographic processing apparatus for processing a film or paper (photographic paper).

[0024]

According to the present invention, there is provided a liquid level detecting device in which the upper surface of the float and the float stop facing the upper surface come into contact with a small contact area. The float easily separates from the float stop due to the small contact area between the upper surface of the float and the float stop facing the upper surface.
Once the float is separated from the float stop, the crystallized portion easily dissolves in the processing solution, and the buoyancy of the float does not change. Therefore, the malfunction of the float is small,
A liquid level detection device excellent in followability and responsiveness of the float to the vertical movement of the liquid level can be obtained.

In a preferred embodiment, the float is
The upper part has a tapered shape. As a result, not only the contact area between the upper surface of the float and the float stop is reduced, but also the accumulation of the processing liquid (for example, the developer) on the upper surface of the float is prevented. As a result, the fixation between the float stop and the upper surface of the float is very effectively prevented,
It is possible to obtain a liquid level detection device which has few malfunctions and is excellent in responsiveness and followability to the liquid level up and down. Furthermore, in such a liquid level detecting device, the processing liquid does not accumulate on the upper surface of the float, so that the buoyancy of the float does not change, and as a result, the liquid level detecting accuracy is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid level detecting device according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of the liquid level detecting device of FIG.

FIG. 3 is a schematic view illustrating a stopper provided in the liquid level detecting device according to a preferred embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining a liquid level detection device according to another embodiment of the present invention, and is a schematic cross-sectional view of a portion corresponding to a cross section taken along line II-II of FIG.

FIG. 5 is a schematic cross-sectional view for explaining a liquid level detecting device according to still another embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view for explaining a liquid level detecting device according to still another embodiment of the present invention.

FIG. 7 is a cross-sectional view of the liquid level detecting device of FIG. 6 taken along line VII-VII.

FIG. 8 is a schematic perspective view illustrating a float of the liquid level detecting device according to the preferred embodiment of the present invention.

FIG. 9 is a schematic sectional view of a conventional liquid level detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reed switch 2 Casing 2 'immersion part 3 Float 4 Magnet 5 Stopper 6 Float stop part 8 Projection part 9 Blade 10 Groove 11 Tapered part 100 Liquid level detecting device

Claims (4)

[Claims] 1. A switch having a vertically long member having a float stop provided at an upper part thereof, and a magnet built-in float which moves up and down along the switch built-in member in accordance with a change in the liquid level. A liquid level detecting device, wherein an upper surface and the float stop facing the upper surface are in contact with a small contact area. 2. The liquid level detecting device according to claim 1, wherein an upper portion of the float has a tapered shape. 3. The switch built-in member has an immersion portion having a circular cross section in which a switch is built, and a float stop formed at an upper portion of the immersion portion and having a diameter larger than that of the immersion portion. 2. A projection is provided on a lower surface of the device.
Or the liquid level detection device according to 2. 4. The liquid level detecting device according to claim 3, wherein the projection includes at least one ridge or columnar projection.