GB2087546A - Apparatus for detecting foreign particles in a liquid - Google Patents
Apparatus for detecting foreign particles in a liquid Download PDFInfo
- Publication number
- GB2087546A GB2087546A GB8034726A GB8034726A GB2087546A GB 2087546 A GB2087546 A GB 2087546A GB 8034726 A GB8034726 A GB 8034726A GB 8034726 A GB8034726 A GB 8034726A GB 2087546 A GB2087546 A GB 2087546A
- Authority
- GB
- United Kingdom
- Prior art keywords
- target
- radiation
- liquid
- sensing element
- area
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000002245 particle Substances 0.000 title claims abstract description 51
- 239000007788 liquid Substances 0.000 title claims abstract description 35
- 230000005855 radiation Effects 0.000 claims abstract description 48
- 239000000725 suspension Substances 0.000 claims abstract description 5
- 230000001678 irradiating effect Effects 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 abstract description 2
- 230000005540 biological transmission Effects 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 description 7
- 238000005286 illumination Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 230000005499 meniscus Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/90—Investigating the presence of flaws or contamination in a container or its contents
- G01N21/9018—Dirt detection in containers
- G01N21/9027—Dirt detection in containers in containers after filling
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0078—Testing material properties on manufactured objects
- G01N33/0081—Containers; Packages; Bottles
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
An apparatus for detecting foreign particles in a liquid comprises a mechanism for bringing the particles into suspension, a radiation source 1 for irradiating the inspected zone of the liquid, and a radiation detector 5 including a projecting system 8 for projecting the image of the inspected zone of the liquid onto the detector which may be the target of a pickup tube 7. The projecting system comprises means 9, 10 for superposing the images of different areas of the inspected zone of the liquid. The particles are brought into suspension by rotating and braking transparent container 2. Radiation from different areas of the container is directed onto the target of tube 7 by mirrors 9, 10 and the tube output 13 connected to a threshold device 6. To ensure equal intensity of at the target, of radiation from different areas of the container, an attenuator 3, with different transmission in different areas is used. Alternatively, several sources may be used. The apparatus can be used for testing foodstuffs and pharmaceutical materials. <IMAGE>
Description
SPECIFICATION
Apparatus for detecting foreign particles in a liquid
The present invention relates to apparatuses for automatically inspecting liquid materials, and more particularly to apparatuses for detecting foreign particles in a liquid.
The present invention can be used for detecting foreign particles in liquids contained in transparent containers. The present invention can most advantageously be used in apparatuses for testing the quality of food-stuffs and pharmaceutical materials.
According to the invention, there is proposed an apparatus for detecting foreign particles in a liquid, comprising a mechanism for bringing the particles into suspension, a radiation source for irradiating the inspected zone of the liquid, a radiation receiving device, and a register means for registering the output signal of the radiation receiving device, the radiation receiving device including a sensing element and a projecting system for projecting the image of the inspected zone of the liquid on the target of the sensing element, wherein, according to the invention, the projecting system comprises a means for superposing the images of different areas of the inspected zone of the liquid.
Such an apparatus makes it possible to increase the dimensions of the inspected zone of the liquid without the need for increasing the size of the target of the sensing element of the radiation receiving device or the sensitivity thereof and thus to ensure a more rapid and reliable detection of foreign particles having a small size.
The means for superposing the images may comprise two flat parallel reflecting surfaces facing each other and positioned between the target of the sensing element and the objective lens of the projecting system, the reflecting surfaces being parallel to the axis of the objective lens.
To compensate for the losses caused by reflection of radiation from the reflecting surfaces a radiation filter can be used which is positioned between the radiation source and the objective lens of the projecting system and is made so that the transparency of its portions traversed by the rays falling on the target of the sensing element of the radiation receiving device after being reflected from a reflecting surface of the means for superposing the images is greater than the transparency of the portion of the filter traversed by the rays falling on the target of the sensing element directly through the lens without reflection from a reflecting surface, and the transparency of the portions of the filter traversed by the rays falling on the target of the sensing element after a greater number of reflections is greater than the transparency of the portions traversed by the rays falling on the target of the sensing element after a smaller number of reflections.
According to another embodiment of the invention compensation for the losses caused by reflection of radiation from the reflecting surfaces may be achieved by using several radiation sources positioned so that the intensity of radiation incident on that area of the inspected zone of the liquid the image of which is projected on the target of the sensing element of the radiation receiving device directly through the objective lens without reflection from a reflecting surface of the means for superposing the images is less than the intensity of radiation incident on that area of the inspected zone the image of which is projected on the target of the sensing element after being reflected from a reflecting surface, and the intensity of radiation incident on that area of the inspected zone the image of which is projected on the target of the sensing element after being reflected is the greater, the greater is the number of reflections undergone by the image of this area before being projected on the target of the sensing element.
The invention is further explained by a detailed description of its preferred embodiments with reference to the accompanying drawings, in which:
FIG. 1 shows a schematic arrangement of an apparatus for detecting foreign particles in a liquid, according to the invention;
FIG. 2 shows an arrangement of the elements of the apparatus for detecting foreign particles in a liquid with the use of two radiation sources.
According to Fig. 1 , the apparatus for detecting foreign particles in a liquid comprises an optical radiation source 1 for illuminating the liquid in a container 2, and an optical filter 3 positioned between the source 1 and the container 2 and having a transparency varying along the height of the filter 3. The apparatus further comprises a mechanism 4 for setting the container 2 in rotation, the radiation receiving device constituted by a television camera 5, and a register means 6 for registering the signal at the output of the television camera 5.
The television camera 5 comprises a pickup tube 7 representing the sensing element of the radiation receiving device and a projecting system for projecting the image of the inspected zone of the liquid in the container 2 on the target of the sensing element of the radiation receiving device, i.e., on the target of the pickup tube 7. The projecting system comprises an objective lens 8 positioned between the container 2 and the target of the pickup tube 7, and a means for superposing the images of different areas of the inspected zone of the liquid, said means including two flat parallel mirrors 9 and 10 positioned between the lens 8 and the target of the tube 7 so that their reflecting surfaces face each other and are parallel to the optical axis of the lens 8. A diaphragm 1 1 is positioned between the lens 8 of the television camera 5 and the container 2.
During inspection the container 2 is set in rotation around its vertical axis, which is followed by braking, whereby the foreign particles present in the liquid are brought into suspension. The light from the source 1 through the optical filter 3 falls on the container 2 illuminating the liquid therein.
The presence of foreign particles in the liquid leads to scattering of the light produced by the source 1.
The light scattered by the particles falls on the target of the pickup tube 7 through the lens 8 which provides focusing of the rays scattered by the particles located in the vertical plane passing through the axis of the container 2 on the target of the pickup tube 7. The diaphragm 11 serves to prevent the light scattered by the bottom of the container 2 and by the meniscus of the liquid from falling on the target of the tube 7.
The rays scattered by the particles located in the central area of the vertical plane whose image is focused on the target of the pickup tube 7, i.e., in the area located between points A1 and A2, fall on the target of the tube 7 directly through the lens 8 without reflection from the mirror 9 or 10.
In Fig. 1 there is shown the passage of one of the rays scattered by the particle located at a point "a" of the area A1A2, i.e., of the ray which passes through the centre of the lens 8. The rays scattered by the particles located in the area A1A2
above and below the point "a" will be respectively focused below and above the point of focusing of the rays scattered by the particle located at the
point "a".
The rays scattered by the particles located in the area of the above-mentioned vertical plane above the area A,A2, i.e., in the area located between the point A, and a point B1, fall on the target of the tube 7 after being reflected from the lower mirror 10. In Fig. 1 there is shown the passage of one of the rays scattered by the particle located at a point "b" of the area A,B1.
The rays scattered by the particles located in the area A1B1 above and below the point "b" will be, after being reflected from the mirror 10, respectively focused above and below the point of focusing of the rays scattered by the particle located at the point "b".
The rays scattered by the particles located in the area above the area A1B1, i.e., in the area located between the point B1 and a point Ci, fall on the target of the tube 7 after being reflected first from the lower mirror 10 and then from the upper mirror 9. In Fig. 1 there is shown the passage of one of the rays scattered by the particle located at a point "c" of the area B,C1. The rays scattered by the particles located in the area
B1C, above and below the point "c" will be, after being reflected first from the mirror 10 and then from the mirror 9, respectively focused below and above the point of focusing of the rays scattered by the particle located at the point "c".
Likewise, the rays scattered by the particles located in the area below the central area A1A2, i.e., in an area A2B2, fall on the target of the tube 7 after being reflected from the upper mirror 9, and the rays scattered by the particles located in an area B2C2 located below the area A2B2 fall on the target of the tube 7 after being reflected first from the upper mirror 9 and then from the lower mirror 1 0.
Thus the mirrors 9 and 10 provide a means for superposing the images of the areas A,A2, A,B,, A2B2, B1C1 and B2C2 of the inspected zone when they are projected on the target of the pickup tube 7. If any particles are present in the neighbourhood of these areas, the images of these particles will be focused at corresponding points of the target of the tube 7, the intensity of the light scattered by a particle and focused at a corresponding point of the target being the greater, the greater is the size of the particle. The falling of the focused rays scattered by a particle on the target of the tube 7 produces a pulse at the output of the television camera 5, said pulse being registered by the register means 6 if the amplitude of the pulse is above a predetermined levei corresponding to the smallest of the particles to be detected.Therefore, the employment of the mirrors 9 and 10 allows to increase several times the dimensions of the liquid zone which can be inspected at a time. In so doing there is no need to increase the focal length of the lens 8 and thus to decrease the size of the particle images on the target of the tube 7, which would have made it necessary to increase the sensitivity and resolution of the camera 5. There is also no need to increase the dimensions of the target of the tube 7.
The optical filter 3 has a transparency varying along its height so that the transparency of its portions traversed by the rays illuminating the areas A,B, and A2B2 of the inspected zone is greater than the transparency of the portion traversed by the rays illuminating the area A,A2 of the inspected zone, and the transparency of the portions of the filter 3 traversed by the rays illuminating the areas B,C, and B2C2 of the inspected zone is greater than the transparency of the portions traversed by the rays illuminating the areas A,B, and A2B2.The differences in the transparencies of these portions of the filter 3 is such that the intensity of the light illuminating the areas A,B, and A2B2 exceeds the intensity of the light illuminating the area A,A2 by a value that ensures compensation for the energy losses caused by a single reflection from the mirror 9 or
10, and the intensity of the light illuminating the areas B,C1 and B2C2 exceeds the intensity of the light illuminating the areas A1B, and A2B2 by a value that ensures compensation for the energy losses caused by a double reflection, i.e., first from the mirror 9 and then from the mirror 10 or vice versa. This ensures the same amplitude of the pulses produced at the output of the television camera 5 in response to the light falling on the target of the tube 7 from the particles of the same size irrespective of the area of the inspected zone in which they are located.
The variable transparency filter 3 may be positioned between the container 2 and the objective lens 8 of the television camera 5. In such a case the inspected zone of the liquid is uniformly illuminated, the compensation for the energy losses caused by reflection from the mirrors 9 and
10 being achieved by reduction in the intensity of the light scattered by the particles located in the area A,A2 with respect to the intensity of the light scattered by the particles located in the areas A1B and A2B2, and by reduction in the intensity of the light scattered by the particles located in the areas
A1B, and A2B2 with respect to the intensity of the light scattered by the particles located in the areas
B1C1 and B2C2.
If necessary, the number of the areas the images of which are superposed can be increased by using the rays falling on the target of the tube 7 after undergoing three or more successive reflections from the mirrors 9 and 10.
Non-uniform illumination of different areas of the inspected zone may be achieved by other means. Thus, if three different areas of the inspected zone are to be superposed when projected on the target of the pickup tube 7, two radiation sources may be used, as shown in Fig. 2.
According to Fig. 2, the apparatus for detecting foreign particles in a liquid further comprises an additional optical radiation source 12, the radiation sources 1 and 12 being directional sources and positioned so that the source 1 illuminates the uppermost area of the inspected zone of the liquid, the image of which is projected on the target of the tube 7 (Fig. 1 ) after being reflected from one of the surfaces 9 or 10, while the source 12 (Fig. 2) illuminates the lowermost area of the inspected zone, the image of which is projected on the target of the tube 7 (Fig. 1 ) after
being reflected from the other of the mirrors 9 or
10. Illumination of the central area of the inspected zone is effected through diffusion of the
light from the sources 1 (Fig. 2) and 12 in the
liquid.As a result, the intensity of the light illuminating the central area of the inspected zone
is smaller than the intensity of the light
illuminating its upper and lower areas, which
provides compensation for the energy losses caused by reflections from the mirrors 9 and 10.
If more than three different areas of the inspected zone projected on the target of the tube
7 (Fig. 1) are superposed, a greater number of
radiation sources illuminating said zone may be
employed so as to ensure a greater intensity of
radiation incident on the area of the inspected zone which undergoes a greater number of
reflections before being projected on the target of the tube 7.
While the invention is described herein in the terms of the preferred embodiments, numerous
modifications may be made without departure from the spirit and scope of the invention as defined by the appended claims.
It will be clear that instead of the flat parallel
mirrors 9 and 10 other means for superposing the projected images may be employed. Such a
means may include, for example, a triangular prism positioned between the container and the objective lens of the projecting system and two tilted mirrors positioned so that the rays scattered
by the particles located in the upper area of the
inspected zone fall on the target of the radiation
receiving device after being reflected from one of the mirrors and one of the sides of the prism, while the rays scattered by the particles located in the lower area of the inspected zone fall on the target of the radiation receiving device after being reflected from the other mirror and the other side of the prism. It is also possible to use a beamsplitting prism and a mirror which are so positioned that the rays scattered by the particles located in one of the areas of the inspected zone fall on the target of the radiation receiving device after passing through the beam-spiitting surface of the prism, while the rays scattered by the particles located in another area of the inspected zone fall on the target of the radiation receiving device after being reflected from the mirror and the beamsplitting surface.
If necessary, the optical radiation source 1 and the television camera 5 may be respectively substituted by a source and a receiver of another type of radiation, such as ultra-high frequency radiation, X-rays, etc.
Claims (5)
1. An apparatus for detecting foreign particles in a liquid, comprising a mechanism for bringing the particles into suspension, a radiation source for irradiating the inspected zone of the liquid, a radiation receiving device, and a register means for registering the output signal of the radiation receiving device, the radiation receiving device including a sensing element and a projecting system for projecting the image of the inspected zone of.the liquid on the target of the sensing element, the projecting system comprising a means for superposing the images of different areas of the inspected zone of the liquid.
2. An apparatus according to Claim 1, wherein the means for superposing the images comprises two flat parallel reflecting surfaces facing each other and positioned between the target of the sensing element and the objective lens of the projecting system, the reflecting surfaces being parallel to the axis of the objective lens.
3. An apparatus according to Claim 2, comprising a radiation filter positioned between the radiation source and the objective lens of the projecting system and made so that the transparency of its portions traversed by the rays falling on the target of the sensing element of the radiation receiving device after being reflected from a reflecting surface of the means for superposing the images is greater than the transparency of the portion of the filter traversed by the rays falling on the target of the sensing element directly through the lens without reflection from a reflecting surface, and the transparency of the portions of the filter traversed by the rays falling on the target of the sensing element after a greater number of reflections is greater than the transparency of the portions traversed by the rays falling on the target of the sensing element after a smaller number of reflections.
4. An apparatus according to Claim 2, comprising several radiation sources positioned so that the intensity of radiation incident on that area of the inspected zone of the liquid the image of which if projected on the target of the sensing element of the radiation receiving device directly through the objective lens without reflection from a reflecting surface of the means for superposing the images is less than the intensity of radiation incident on that area of the inspected zone the image of which is projected on the target of the sensing element after being reflected from a reflecting surface, and the intensity of radiation incident on that area of the inspected zone the image of which is projected on the target of the sensing element after being reflected is the greater, the greater is the number of reflections undergone by the image of this area before being projected on the target of the sensing element.
5. An apparatus for detecting foreign particles in a liquid substantiaily as hereinabove described with reference to and as shown in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8034726A GB2087546B (en) | 1980-10-29 | 1980-10-29 | Apparatus for detecting foreign articles in a liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8034726A GB2087546B (en) | 1980-10-29 | 1980-10-29 | Apparatus for detecting foreign articles in a liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2087546A true GB2087546A (en) | 1982-05-26 |
| GB2087546B GB2087546B (en) | 1984-07-18 |
Family
ID=10516936
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8034726A Expired GB2087546B (en) | 1980-10-29 | 1980-10-29 | Apparatus for detecting foreign articles in a liquid |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2087546B (en) |
-
1980
- 1980-10-29 GB GB8034726A patent/GB2087546B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2087546B (en) | 1984-07-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |