JP2003270143A - Liquid quantity detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a liquid quantity detecting device in which a light receiving part can receive a stable amount of light irradiated by a light emission part of a sensor of the liquid quantity detecting device without affected by dusts. <P>SOLUTION: The liquid quantity detecting device comprises an optically transparent case 2 in which liquid having refractive index, and reflectance which are not as same as those of air, and a sensor 1 which detects the amount of the liquid in the case utilizing the shape of the optically transparent case, wherein the position of the case containing the liquid where the sensor 1 is provided has a double structure. To be more specific, the sensor 1 comprising a light emission part 1a and a light receiving part 1b is located such that the position of the double structure in the case is sandwiched with the light emission part 1a and the light receiving part 1b, and the position of the double structure in the case comprises a protruded inner wall 2a which is diagonally across with a light axis of the sensor 1 and a protruded outer wall 2b which is orthogonal across with a light axis of the sensor 1 and covers the protruded inner wall 2a. <P>COPYRIGHT: (C)2003,JPO

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 applicable to all fields for detecting a liquid level, and particularly to a liquid level detecting device represented by an oil tank of a fixing portion of an image forming apparatus. The present invention relates to a liquid amount detection device suitable for.

[0002]

2. Description of the Related Art There are various types of liquid amount detecting devices for detecting the amount of liquid in the case of a tank containing a liquid.
If the case of the oil tank is made of a light-transmissive material, such as an oil tank used in the fixing section of an image forming apparatus such as a copying machine or a printer, the amount of liquid in the case is detected by the light emitting section and the light receiving section. There is known a liquid amount detection device that optically detects by using a sensor having a plurality of parts.

Here, FIG. 4 is a diagram showing an example of a liquid amount detecting device for optically detecting the amount of liquid in the oil tank case, and is a perspective view of the liquid amount detecting sensor and the oil tank case. . 5 to 7 are schematic cross-sectional views showing the structure of the sensor arrangement portion of the oil tank case.
Shows a state in which there is no liquid (for example, oil) which is a non-detection body in the oil tank case, FIG. 6 shows a state in which oil is present in the oil tank case, and FIG. 7 shows false detection due to liquid amount detection. It shows the state when doing. Below, FIG.
The conventional liquid amount detecting method will be briefly described with reference to FIGS.

The sensor 1 is an optical sensor including a light emitting portion 1a including a light emitting element (for example, a light emitting diode (LED)) and a light receiving portion 1b including a light receiving element (for example, a photodiode (PD)). , The light from the light emitting unit 1a is received by the light receiving unit 1b, and the ON-OF
A sensor that outputs an F signal is used. The oil tank case 2 is made of a light transmissive material such as a light transmissive resin, and a part of the wall surface of the oil tank case 2 is formed so as to cross the optical axis of the sensor 1 obliquely. A protruding portion 2a having a substantially triangular shape is provided between the light emitting portion 1a and the light receiving portion 1b, and the sensor 1 is configured to detect the oil 3 in the protruding portion 2a.
That is, since the oil 3 contained in the oil tank case 2 has a different refractive index / reflectance from air (usually,
Since oil has a higher refractive index than air), the amount of light that passes through the protruding portion 2a differs depending on whether the oil 3 is present in the protruding portion 2a of the oil tank case 2 or not. It is possible to detect the liquid amount by detecting with 1.

With this structure, when the oil 3 is not present in the oil tank case 2, as shown in FIG. 5, the outside and inside of the projecting portion 2a of the oil tank case 2 become air. , Since the refractive index is the same,
The light emitted from the projection 2a of the oil tank case 2
Is transmitted almost linearly and reaches the light receiving portion 1b, the amount of light received by the light receiving portion 1b increases, and the ON signal is output from the light receiving portion 1b.

Next, the protruding portion 2 of the oil tank case 2
When the oil 3 is in a, the refractive index inside the protrusion 2a becomes larger than that of air, and this protrusion 2a acts like a prism, so that it is emitted from the light emitting portion 1a as shown in FIG. The light changes its direction due to the difference in refractive index between the oil 3 and the outside air 4 and does not reach the light receiving portion 1b, so that the amount of light received at the light receiving portion 1b is greatly reduced, and the output signal of the light receiving portion 1b is turned off. Become. Therefore, O of the output signal of the light receiving unit 1b
The liquid amount can be detected by detecting N-OFF.

[0007]

However, in the arrangement of the oil tank case 2 and the sensor 1 configured as shown in FIG. 4, the outside air 4 outside the oil tank case 2 has dust 5 which is affected by the refractive index. When it is contaminated with dust, dust 5 adheres to the surface of the protrusion 2a of the oil tank case 2, and as shown in FIG. When the light from the portion 1a enters the protruding portion 2a of the oil tank case 2 or is emitted from the protruding portion 1a, it is refracted to receive light even though there is no oil 3 in the protruding portion 2a of the oil tank case 2. There occurs a phenomenon that light does not reach the portion 1b, or that light reaches the light receiving portion 1b even though the oil 3 is present in the protruding portion 2a. In such a state, there is a problem in that the amount of light received by the light receiving section 1b varies, and erroneous detection may occur depending on the magnitude of this variation.

The present invention has been made in view of the above circumstances, so that the light emitted from the light emitting portion side of the sensor for detecting the liquid amount can reach a stable light amount to the light receiving portion side without being affected by dust or the like. It is an object of the present invention to provide a liquid amount detection device having a configuration capable of achieving the above.

[0009]

In order to achieve the above object, the present invention adopts the following configurations. (1). In a liquid amount detection device having a light-transmissive case that contains a liquid having a different refractive index / reflectance from air, and a sensor that detects the liquid amount in the case by utilizing the shape of the light-transmissive case, The portion of the case that accommodates the sensor has a double structure (claim 1). (2). In the liquid amount detection device having the configuration of (1), the sensor includes a light emitting portion and a light receiving portion, and the sensor is arranged so that the light emitting portion and the light receiving portion sandwich the double-structured portion of the case (claim 2). . (3). In the liquid amount detection device having the configuration of (2), the double-structured portion of the case has an inner wall projecting obliquely across the optical axis of the sensor and a direction orthogonal to the optical axis of the sensor. And an outer wall that projects and covers the inner wall (claim 3). (4). In the liquid amount detection device having the configuration (1), the sensor is arranged between the walls of the double structure of the case that contains the liquid, and the case wall surface outside the sensor is made of an impermeable material. 4). (5). In the liquid amount detection device having the configuration of (4), the sensor includes a light emitting portion and a light receiving portion, and the double-structured portion of the case has an inner wall projecting obliquely across the optical axis of the sensor. , And an impermeable outer wall that covers the sensor (claim 5). (6). In the liquid amount detection device having the configuration (1), the case containing the liquid is made of a material that is light-transmissive and has substantially the same refractive index and reflectance as the liquid of the non-detection body, A sensor having a light emitting portion and a light receiving portion is embedded in a double wall of the case (claim 6).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) First, an embodiment of the configuration according to (1), (2) and (3) of the above-mentioned solving means will be described. 1A and 1B are views showing an embodiment of a liquid amount detecting device according to the present invention, wherein FIG. 1A is a perspective view of a liquid amount detecting sensor and an oil tank case, and FIG. 1B is a sensor of the oil tank case. It is a schematic main part sectional view which shows the structure of an arrangement | positioning part.

In FIG. 1, a sensor 1 for detecting a liquid amount is
For example, a light emitting portion 1a including a light emitting element such as a light emitting diode (LED) or an LED array, and a photodiode (P
D) or a multi-division PD (line sensor) or the like, which is an optical sensor configured with a light receiving portion 1b including a light receiving element. Light from the light emitting portion 1a is received by the light receiving portion 1b, and O
A sensor that outputs an N-OFF signal is used.
The oil tank case 2 is made of a light-transmissive material, and a portion of the oil tank case 2 where the sensor 1 is arranged has a double structure. The part has a rectangular shape that projects from the inner wall of the sensor 1 in a direction that is orthogonal to the optical axis of the sensor 1 and that projects from the inner wall of the sensor 1 that extends obliquely across the optical axis of the sensor 1. It is configured with the outer wall 2b. The outer wall 2b of the oil tank case 2 is also made of a light-transmissive material, and a sealed space is formed between the outer wall 2b and the inner wall (protruding portion) 2a. Then, the sensor 1 is arranged so that the light emitting portion 1a and the light receiving portion 1b sandwich the double-structured portion of the oil tank case 2 including the inner wall 2a and the outer wall 2b.
Are arranged.

As shown in FIG. 1, the sensor 1 is configured to detect the amount of light transmitted through the double-structured portion of the oil tank case 2, but the oil contained in the oil tank case 2 is stored in the sensor 1. 3 has a refractive index / reflectance different from that of air (usually, oil has a higher refractive index than air), so that the protrusion 2a formed by the inner wall of the oil tank case 2 is provided.
Depending on whether or not there is oil 3 in the protrusion 2a.
Since the amount of light that passes through is different, the liquid amount can be detected by detecting the change in the amount of light with the sensor 1.

That is, when there is no oil 3 in the oil tank case 2, the protruding portion 2 of the oil tank case 2
Since the inside and outside of a are air, and therefore have the same refractive index, the light emitted from the light emitting portion 1a is transmitted substantially linearly through the outer wall 2b and the protruding portion 2a of the oil tank case 2 and the light receiving portion 1b. Since the amount of light received by the light receiving section 1b increases, an ON signal is output from the light receiving section 1b. Further, when the oil 3 is present on the protruding portion 2a of the oil tank case 2, the refractive index inside the protruding portion 2a becomes larger than that of air, and the protruding portion 2a acts like a prism, so that the light emitting unit 1
After the light emitted from a passes through the outer wall 2b, the direction of the light changes due to the difference in refractive index between the oil 3 and the outside air 4 in the protruding portion 2a and does not reach the side surface 2c of the outer wall on the light receiving portion 1b side.
The amount of light received by the light receiving section 1b is greatly reduced, and the output signal of the light receiving section 1b is turned off. Therefore, the liquid amount can be detected by detecting ON-OFF of the output signal of the light receiving unit 1b. Further, by using a multi-division PD (line sensor) for the light receiving section 1b and detecting the element position at the boundary where ON-OFF is switched, the liquid surface position and the liquid amount can be accurately detected.

In the configuration shown in FIG. 1, the portion of the oil tank case 2 where the sensor 1 is arranged has a double structure, and the rectangular outer wall 2b that covers the protrusion 2a is provided. Even when the outside air 4 is contaminated with the dust 5 that is affected by the refractive index, it is possible to prevent the dust from entering the outer wall of the oil tank case 2 and attach the dust to the surface of the protruding portion 2a of the inner wall. There is nothing to do. Further, since the sensor 1 is arranged such that the side surface 2c of the outer wall 2b of the oil tank case 2 is sandwiched between the light emitting portion 1a and the light receiving portion 1b, dust enters between the light emitting portion 1a or the light receiving portion 1b and the outer wall 2b. Can also be prevented. Therefore, in the configuration shown in FIG. 1, the light emitted from the light emitting portion 1a side of the sensor 1 for liquid amount detection is not affected by dust adhering to the surface of the oil tank case 2, and a stable light amount is obtained. It is possible to reach the light receiving portion 1b side, and it is possible to receive a constantly stable light amount on the light receiving portion 1b side without variation.

(Embodiment 2) Next, an embodiment of the configuration according to (1), (4) and (5) of the above-mentioned solving means will be described. 2A and 2B are views showing another embodiment of the liquid amount detecting device according to the present invention, in which FIG. 2A is a perspective view of a liquid amount detecting sensor and an oil tank case, and FIG. It is a schematic main part sectional view which shows the structure of a sensor arrangement part.

In FIG. 2, the sensor 1 for detecting the liquid amount is similar to the first embodiment in that a light emitting portion 1a including a light emitting element such as a light emitting diode (LED) or an LED array, a photodiode (PD) or a multi-divided PD ( It is an optical sensor including a light receiving portion 1b including a light receiving element such as a line sensor).
The oil tank case 2 is made of a light-transmissive material, and a portion of the oil tank case 2 where the sensor 1 is arranged has a double structure. The sensor 1 is arranged between the wall surfaces, and the case wall surface 2d outside the sensor 1 is made of an impermeable material. That is, in the configuration shown in FIG. 2, the double-structured portion of the oil tank case 2 has a projecting portion 2a having an inner wall projecting obliquely across the optical axis of the sensor 1 and a projecting portion having this inner wall. 2a and an impermeable outer wall 2d that covers the sensor 1. The sensor 1 is arranged inside the outer wall 2d so that the protrusion 2a of the inner wall is sandwiched between the light emitting portion 1a and the light receiving portion 1b.

As shown in FIG. 2, the sensor 1 is configured to detect the amount of light transmitted through the protruding portion 2a of the inner wall of the oil tank case 2, but the oil contained in the oil tank case 2 3 has a refractive index / reflectance different from that of air (usually, oil has a higher refractive index than air), so that the protrusion 2a formed by the inner wall of the oil tank case 2 is provided.
Depending on whether or not there is oil 3 in the protrusion 2a.
Since the amount of light that passes through is different, the liquid amount can be detected by detecting the change in the amount of light with the sensor 1.

That is, when there is no oil 3 in the oil tank case 2, the protruding portion 2 of the oil tank case 2
Since the inside and outside of a are air, the refractive index is the same, so that the light emitted from the light emitting portion 1a almost linearly passes through the protruding portion 2a of the oil tank case 2 and reaches the light receiving portion 1b. , The amount of light received by the light receiving section 1b increases,
An ON signal is output from b. Further, when the oil 3 is present on the protruding portion 2 a of the oil tank case 2, the protruding portion 2 a
Since the refractive index inside a is larger than that of air, and this protruding portion 2a acts like a prism, the light emitted from the light emitting portion 1a is refracted between the oil 3 inside the protruding portion 2a and the air inside the outer wall 2d. The direction of light changes due to the difference in the ratio, and the light receiving part 1b
Therefore, the amount of light received by the light receiving unit 1b is significantly reduced, and the output signal of the light receiving unit 1b is turned off. Therefore, the liquid amount can be detected by detecting ON-OFF of the output signal of the light receiving unit 1b. Further, by using a multi-division PD (line sensor) for the light receiving section 1b and detecting the element position at the boundary where ON-OFF is switched, the liquid surface position and the liquid amount can be accurately detected.

In the structure shown in FIG. 2, the portion of the oil tank case 2 in which the sensor 1 is arranged has a double structure, and a rectangular non-permeable outer wall 2d for covering the protrusion 2a and the sensor 1 is provided. Even when the outside air 4 outside the oil tank case 2 is contaminated with dust 5 that is affected by the refractive index, the contaminated outside air 4 and dust 5 are prevented from entering the outer wall of the oil tank case 2. Can be prevented, the protrusion 2 on the inner wall
Dust does not adhere to the surface of a, the light emitting portion 1a and the light receiving portion 1b of the sensor 1. Therefore, in the configuration shown in FIG.
The light emitted from the light emitting portion 1a side of the sensor 1 for detecting the liquid amount is not affected by the dust 5 adhering to the surface of the oil tank case 2 or the contaminated outside air 4 at all, and a stable light amount is obtained on the light receiving portion 1b side. Therefore, it is possible to always receive a stable light amount without variation on the light receiving portion 1b side. Further, by covering the periphery of the protrusion 2a and the sensor 1 with the rectangular non-transparent outer wall 2d, an effect of not being affected by ambient light can be obtained, and the liquid amount detection accuracy can be improved.

(Embodiment 3) Next, an embodiment of the configuration according to (1) and (6) of the above-mentioned solving means will be described. FIG. 3 is a view showing another embodiment of the liquid amount detection device according to the present invention, and FIGS. 3 (a) and 3 (b) are schematic cross-sectional views showing the structure of the sensor arrangement portion of the oil tank case. Incidentally, FIG. 3 (a)
Shows a state where oil is contained in the oil tank case, and (b) shows a state where oil is not contained in the oil tank case.

In FIG. 3, the sensor 1 for detecting the liquid amount is similar to the first embodiment in that a light emitting portion 1a including a light emitting element such as a light emitting diode (LED) or an LED array, a photodiode (PD) or a multi-divided PD ( It is an optical sensor including a light receiving portion 1b including a light receiving element such as a line sensor).
In addition, the oil tank case 2 that contains the oil 3 is an oil 3 that is light-transmissive and has a non-detectable body with a refractive index and a reflectance.
The oil tank case 2 is made of a material having the same refractive index and reflectance as that of the oil tank case 2, and the sensor including the light emitting portion 1a and the light receiving portion 1b is embedded in the double wall 2f of the oil tank case 2. . Further, the light emitting portion 1a and the light receiving portion 1b of the sensor
On the inner wall surface of the oil tank case 2 between the two, a triangular protrusion 2 protruding obliquely across the optical axis of the sensor 1 is formed.
e is provided. Although an overall view of the oil tank case 2 is omitted, in the configuration of the present embodiment, the sensor is embedded in the double-walled portion 2f of the oil tank case 2, so that the outside of the oil tank case 2 is covered. The wall surface can be configured by a flat surface without unevenness.

In the configuration shown in FIG. 3, when the oil 3 is present in the oil tank case 2, the light emitted from the light emitting portion 1a of the sensor is transferred to the oil tank case 2 and the oil as shown in FIG. Since the refractive index of 3 is set to be the same, the light is transmitted through the protruding portion 2e of the oil tank case 2 and reaches the light receiving portion 1b in a substantially linear manner. Therefore, the amount of light received by the light receiving portion 1b becomes large, and the light receiving portion 1b increases. The ON signal is output from. Further, as shown in FIG. 2B, when there is no oil 3 in the oil tank case 2, the oil tank case 2
Since the internal air and the oil tank case 2 have different refractive indices, the light is refracted or reflected by the protruding portion 2e provided on the inner wall surface of the oil tank case 2 as in the optical path shown in FIG. Since it does not reach the light receiving portion 1b, the amount of light received at the light receiving portion 1b is greatly reduced, and the output signal of the light receiving portion 1b becomes O.
It becomes FF. Therefore, the output signal of the light receiving unit 1b is turned ON-O.
The liquid amount can be detected by detecting the FF. Further, by using a multi-division PD (line sensor) for the light receiving section 1b and detecting the element position at the boundary where ON-OFF is switched, the liquid surface position and the liquid amount can be accurately detected.

In the configuration shown in FIG. 3, the oil tank case 2 is made of a material that is light-transmissive and has a refractive index / reflectance similar to that of the oil 3, and the oil tank case 2 Since the sensor including the light emitting portion 1a and the light receiving portion 1b is embedded in the double-walled wall 2f, the outside air 4 outside the oil tank case 2 is contaminated with dust 5 which is affected by the refractive index. Even when the oil tank case 2 is contaminated, the contaminated outside air and dust do not enter the oil tank case 2, so that dust adheres to the surface of the protruding portion 2e on the inner wall surface, the light emitting portion 1a and the light receiving portion 1b of the sensor. Never.
Therefore, in the configuration shown in FIG. 3, since there is no contaminated air or dust between the light emitting portion 1a and the light receiving portion 1b of the sensor for detecting the liquid amount, a stable amount of light reaches the light receiving portion 1b side. Therefore, it is possible to always receive a stable light amount without variation on the light receiving portion 1b side.

In the first to third embodiments described above, as the light receiving portion 1b constituting the sensor 1, a light receiving element such as a photodiode (PD) or a multi-divided PD (line sensor) is given as an example. In addition to this, PSD (Posi
tion Sensitive Light Detector) and CCD (Charge Co
Upled Device) and the like can be preferably used. In particular, if an LED array is used for the light emitting unit 1a and a CCD that is a one-dimensional image sensor is used for the light receiving unit 1b, the position and amount of the liquid surface in the oil tank case 2 can be easily and accurately detected. The detection accuracy can be further improved.
Further, in the above embodiment, the configuration for detecting the liquid amount of the oil 3 accommodated in the oil tank case 2 has been described, but the present invention is not limited to the oil, and the liquid surface and the liquid amount of various liquids are detected. It can be applied to various fields.

[0025]

As described above, in the liquid amount detecting device according to the present invention, the part of the case for containing the liquid in which the sensor is arranged has a double structure, and the part of the double structure of the case serves as the light emitting part. The sensor is arranged so as to be sandwiched between the light receiving parts, or the sensor is arranged between the walls of the double structure of the case that contains the liquid, and the case wall surface outside the sensor is made of an impermeable material, or The case containing the liquid is made of a material that is light-transmissive and has a refractive index / reflectance substantially the same as the liquid of the non-detection body, and the light-emitting portion is formed on the wall of the double structure of the case. Since the sensor consisting of the light receiving part and the light receiving part is embedded, the light emitted from the light emitting part of the sensor for detecting the liquid amount is not affected by dust outside the case or contaminated outside air To reach the light receiving side Since it makes it possible to receive a constantly stable amount with no variation in the light receiving side, it is possible to improve the liquid amount detection accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a liquid amount detecting device according to the present invention, in which (a) is a perspective view of a liquid amount detecting sensor and an oil tank case, and (b) is a view showing the oil tank case. It is a schematic main part sectional view which shows the structure of a sensor arrangement part.

2A and 2B are views showing another embodiment of the liquid amount detection device according to the present invention, in which FIG. 2A is a perspective view of a liquid amount detection sensor and an oil tank case, and FIG. 2B is the oil tank case. FIG. 3 is a schematic cross-sectional view of essential parts showing the structure of the sensor arrangement part of FIG.

FIG. 3 is a view showing another embodiment of the liquid amount detection device according to the present invention, and FIGS. 3 (a) and 3 (b) are schematic cross-sectional views showing the structure of the sensor arrangement portion of the oil tank case.

FIG. 4 is a view showing a conventional example of a liquid amount detection device that optically detects the amount of liquid in an oil tank case, and is a perspective view of a sensor for detecting a liquid amount and an oil tank case.

5 is a schematic sectional view showing a structure of a sensor arrangement portion of the oil tank case shown in FIG. 4, showing a state where there is no oil in the oil tank case.

6 is a schematic main-portion cross-sectional view showing the structure of a sensor placement portion of the oil tank case shown in FIG. 4, showing a state in which oil is present in the oil tank case.

7 is a schematic cross-sectional view of a main part showing a structure of a sensor arrangement portion of the oil tank case shown in FIG. 4, showing a state in which an erroneous detection is made by liquid amount detection.

[Explanation of symbols]

1 sensor 1a light emitting part 1b Light receiving part 2 oil tank case 2a Projection part consisting of inner wall 2b Light transmissive outer wall 2d non-permeable outer wall 2e Inner wall surface protrusion 2f Double structure wall 3 oil (liquid) 4 outside air 5 garbage

Claims (6)

[Claims] 1. A liquid amount having a light-transmissive case containing a liquid having a different refractive index / reflectance from air, and a sensor for detecting the liquid amount in the case by utilizing the shape of the light-transmissive case. In the detection device, a part of the case that stores the liquid in which the sensor is arranged has a double structure, and the liquid amount detection device. 2. The liquid amount detecting device according to claim 1, wherein the sensor comprises a light emitting portion and a light receiving portion, and
A liquid amount detection device, in which a sensor is arranged such that a light-emitting portion and a light-receiving portion sandwich a portion having a heavy structure. 3. The liquid amount detection device according to claim 2, wherein the double-structured portion of the case has an inner wall projecting obliquely across the optical axis of the sensor and an optical axis of the sensor. A liquid amount detection device comprising an outer wall protruding in a direction orthogonal to each other and covering the inner wall. 4. The liquid amount detection device according to claim 1, wherein a sensor is disposed between the walls of the double structure of the case that contains the liquid, and the case wall outside the sensor is made of a non-transparent material. A liquid amount detecting device characterized in that 5. The liquid amount detection device according to claim 4, wherein the sensor comprises a light emitting portion and a light receiving portion, and
The liquid amount detecting device, wherein the portion of the heavy structure is composed of an inner wall having a shape protruding so as to obliquely cross the optical axis of the sensor, and an impermeable outer wall covering the inner wall and the sensor. 6. The liquid amount detecting device according to claim 1, wherein the case containing the liquid is made of a material which is light-transmissive and has substantially the same refractive index and reflectance as the liquid of the non-detection body. A liquid amount detection device comprising a sensor having a light emitting portion and a light receiving portion embedded in a double wall of the case.