Abstrict The invention provides a flow meter which is structured in a compact
size, and outputs an electric signal of a position of a float within
a taper-shaped tube precisely. A taper-shaped tube (1) is made of
an approximately transparent material, is mounted approximately
vertically, and circulates a fluid (2) such as a water or the like,
and a float (3) is arranged within the taper-shaped tube (1) so
as to displace in a vertical direction in correspondence to a flow
rate of the fluid (2). An LED (4) irradiates a light ray to the
taper-shaped tube (1) and the float (3), makes the light ray to
transmit through the taper-shaped tube (1), and generates a transmitted
light ray (20), the transmitted light ray (20) is input and reflected
to a first mirror (7), and the transmitted light ray (20) is input
and reflected from the first mirror (7) to a second mirror (8).
The transmitted light ray (20) is input from the second mirror (8)
to an image sensor (9), the image sensor (9) outputs a digital image
(1a, 3a) of the float (3) within the taper-shaped tube (1), and
a control portion (11) executes an input process of the digital
signal (1a, 3a), detects the position of the float (3), and outputs
an electric signal (S1) showing a flow rate of the fluid (2).
Claims 1. A flow meter comprising: a taper-shaped tube which is made of
an approximately transparent or semi-transparent material, is mounted
approximately vertically, and circulates a fluid; a float which
is arranged within said taper-shaped tube so as to be displaced
in a vertical direction in correspondence to a flow rate of said
fluid; a light emitting means which irradiates a light ray to said
taper-shaped tube and said float, and transmits or reflects the
light ray; a first mirror to which said transmitted or reflected
light ray is input and reflected; a second mirror to which said
transmitted or reflected light ray is input and reflected from said
first mirror; an image sensor to which said transmitted or reflected
light ray is input from said second mirror, and which outputs a
digital image of said float within said taper-shaped tube; and a
control portion which executes an input process of said digital
signal, detects the position of said float within said taper-shaped
tube, and outputs an electric signal showing said flow rate.
2. A flow meter as claimed in claim 1 further comprising one or
more third mirrors which are interposed between said first mirror
and said second mirror, and to which said transmitted or reflected
light ray is sequentially input and reflected.
3. A flow meter as claimed in claim 1 wherein said light emitting
means is constituted by a plurality of LED arranged along said taper-shaped
tube, and the flow meter is provided with a polarizing prism which
uniformizes said light ray irradiated from said LED, and refracts
an optical path of said light ray so as to irradiate to said taper-shaped
tube and said float.
4. A flow meter as claimed in claim 1 wherein said light emitting
means is constituted by a luminous body uniformly emitting and irradiating
said light ray.
5. A flow meter as claimed in claim 1 wherein a lens for compensating
a difference in an optical path length of said transmitted or reflected
light ray is provided just before said image sensor.
Description TECHNICAL FIELD
[0001] The present invention relates to a flow meter for measuring
a flow rate of a fluid by detecting a position of a float within
a taper-shaped tube by means of an image sensor.
BACKGROUND ART
[0002] In conventional, in Japanese Unexamined Patent Publication
No. 2001-221666 the inventor of the present invention has proposed
an area flow meter having a sensor which is precise, compact and
inexpensive. The conventional area flow meter having the sensor
is structured such that a float moving up and down on the basis
of a flow rate is provided within the taper tube having a translucency,
a fluid to be measured flows therein from an inflow port in a lower
portion and flows toward an inflow port in an upper portion, and
plural sets of image sensor units each constituted by an optical
lens and an image sensor are arranged along a vertical direction
in one side of the taper tube.
DISCLOSURE OF INVENTION
[0003] Accordingly, an object of the present invention is to provide
a flow meter which is structured in a compact size, and outputs
an electric signal of a position of a float within a taper-shaped
tube precisely.
[0004] In order to achieve the object mentioned above, in accordance
with the present invention, there is provided with a flow meter
comprising:
[0005] a taper-shaped tube which is made of an approximately transparent
or semi-transparent material, is mounted approximately vertically,
and circulates a fluid;
[0006] a float which is arranged within the taper-shaped tube so
as to be displaced in a vertical direction in correspondence to
a flow rate of the fluid;
[0007] a light emitting means which irradiates a light ray to the
taper-shaped tube and the float, and transmits or reflects the light
ray;
[0008] a first mirror to which the transmitted or reflected light
ray is input and reflected;
[0009] a second mirror to which the transmitted or reflected light
ray is input and reflected from the first mirror;
[0010] an image sensor to which the transmitted or reflected light
ray is input from the second mirror, and which outputs a digital
image of the float within the taper-shaped tube; and
[0011] a control portion which executes an input process of the
digital signal, detects the position of the float within the taper-shaped
tube, and outputs an electric signal showing the flow rate.
[0012] In accordance with the flow meter of the present invention,
since the structure is made such that the light emitting means irradiates
the light ray to the taper-shaped tube and the float, and transmits
or reflects the light ray, and the transmitted or reflected light
ray is sequentially input and reflected to the first mirror and
the second mirror, and is input to the image sensor, a distance
between the taper-shaped tube, and the float and the image sensor
is formed short in spite that a required optical path length of
the transmitted or reflected light ray can be secured, so that a
whole can be structured compact.
[0013] Further, since the image sensor is used in place of a light
receiving element array, a resolving power is high, so that it is
possible to output an electric signal of the position of the float
within the taper-shaped tube with a high precision.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1A is a plan view including a cross sectional view
of an embodiment 1 in accordance with the present invention;
[0015] FIG. 1B is a front elevational view including a cross sectional
view;
[0016] FIG. 2 is a perspective view of the embodiment 1 in accordance
with the present invention;
[0017] FIG. 3A is a front elevational view including a partial
cross section of a taper-shaped tube structuring the embodiment
1 in accordance with the present invention;
[0018] FIG. 3B is a view as seen from an arrow A-A in FIG. 3A;
[0019] FIG. 4 is a perspective view of the taper-shaped tube structuring
the embodiment 1 in accordance with the present invention;
[0020] FIG. 5 is a schematic view of an LED and a polarizing prism
structuring the embodiment 1 in accordance with the present invention;
[0021] FIG. 6 is a perspective view of the LED and the polarizing
prism structuring the embodiment 1 in accordance with the present
invention;
[0022] FIG. 7 is a schematic view of an embodiment 2 in accordance
with the present invention;
[0023] FIG. 8 is a digital image view obtained by imaging the transmitted
or reflected light ray in accordance with the embodiment 1 of the
present invention by an image sensor; and
[0024] FIG. 9 is an explanatory view showing a relation between
an electric signal output from the embodiment 1 in accordance with
the present invention and a position of a float.
BEST MODE FOR CARRYING OUT THE INVENTION
[0025] A description will be given of the present invention on
the basis of embodiments with reference to the accompanying drawings.
[0026] FIG. 1A is a plan view including a partial cross section
of an embodiment 1 in accordance with the present invention, FIG.
1B is a front elevational view including a partial cross section,
FIG. 2 is a perspective view, FIG. 3A is a front elevational view
including a partial cross section of a taper-shaped tube structuring
the embodiment 1 in accordance with the present invention, FIG.
3B is a view as seen from an arrow A-A in FIG. 3A, and FIG. 4 is
a perspective view.
[0027] A taper-shaped tube 1 is made of an approximately transparent
or semi-transparent material, is mounted approximately vertically,
and circulates a fluid 2 such as a water or the like. The measured
fluid 2 flows therein from an inflow port 1a in a lower portion,
and flows out from an outflow port 1b in an upper portion. A float
3 is arranged within the taper-shaped tube 1 so as to displace in
a vertical direction in correspondence to a flow rate of the fluid
2.
[0028] As shown in FIGS. 5A, 5B, 5C, 5D, 5E and 6 a light emitting
means is constituted by an LED 4 irradiates the light ray to the
taper-shaped tube 1 and the float 3 and makes the light ray to
transmit through the taper-shaped tube 1 so as to form a transmitted
light ray 20.
[0029] A plurality of LED 4 are arranged along the taper-shaped
tube 1 a polarizing prism 5 uniformizes the light ray irradiated
from the LED 4 and refracts an optical path of the light ray so
as to irradiate to the taper-shaped tube 1 and the float 3. As shown
in FIGS. 5 and 6 the LED 4 and the polarizing prism 5 are fixed
to a plate 14 and are closed by plates 15 and 16 as shown in FIG.
2.
[0030] A first mirror 7 is structured such that the transmitted
light ray 20 is input and reflected thereto, and a second mirror
8 is structured such that the transmitted light ray 20 is input
and reflected thereto from the first mirror 7.
[0031] The transmitted light ray 20 is input to an image sensor
9 such as a CCD type, a CMOS type, a POC type or the like image
sensor from the second mirror 8 and the image sensor 9 outputs
digital images 1a, 1a and 3a of the float 3 within the taper-shaped
tube 1 which are shown in FIG. 8.
[0032] In the present embodiment 1 a lens 10 for compensating
a difference in an optical path length of the transmitted light
ray 20 is provided just before the image sensor 9.
[0033] A control portion 11 executes an input process of the digital
images 1a, 1a and 3a, detects the position of the float 3 within
the taper-shaped tube 1 and outputs an electric signal S1 shown
in FIG. 9 showing a flow rate of the fluid 2. The electric signal
S1 displays the flow rate of the fluid 2 by means of a display meter
(not shown) or the like.
[0034] In an embodiment 2 in accordance with the present invention
shown in FIG. 7 the light emitting means is constituted by a liquid
crystal 12 or the like corresponding to a luminous body uniformly
emitting and irradiating the light ray.
[0035] Further, a projector 12 such as a slide projector or the
like corresponding to the light emitting means reflects the light
ray to the taper-shaped tube 1 and the float 3 and forms the reflected
light ray 20.
[0036] Further, one or more third mirrors 13 are interposed between
the first mirror 7 and the second mirror 8 and the transmitted
or reflected light ray 20 is sequentially input and reflected. |