GB2259568A - Monitoring fluid dispensing nozzle - Google Patents
Monitoring fluid dispensing nozzle Download PDFInfo
- Publication number
- GB2259568A GB2259568A GB9119122A GB9119122A GB2259568A GB 2259568 A GB2259568 A GB 2259568A GB 9119122 A GB9119122 A GB 9119122A GB 9119122 A GB9119122 A GB 9119122A GB 2259568 A GB2259568 A GB 2259568A
- Authority
- GB
- United Kingdom
- Prior art keywords
- droplet
- nozzle
- fluid
- dispensing
- amount
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F3/00—Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01F1/661—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters using light
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Coating Apparatus (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
The operation of a nozzle 2 for dispensing drops of adhesive onto a circuit board is optically monitored. An LED source 12 illuminates the nozzle 2 through a lens 14. A droplet 10 on the nozzle casts a shadow on a photodiode detector 8. An output voltage from the detector 8 is measured before and after droplet formation, and again after the droplet has been released. The measured voltages are compared with standard values to determine whether the droplet is of an acceptable size. The optical system may include reflecting prisms, or a TV camera coupled to a pattern recognition system. <IMAGE>
Description
MONITORING SYSTEM
The present invention relates to an improved system for monitoring the operation of a dispensing nozzle for aispensing fluids. The system is particularly suitable for monitoring the dispensing of an adhesive, for example an spoxy or acrylic adhesive, from a nozzle, onto the surface of an object, for example a circuit board, that is moved between selected locations.
renown dispensing systems control the amount of fluid dispensed by che nozzle by controiling the time during which a syringe attached to the nozzle is dispensing fluid. This method has che disadvantage that any variation in the amount of fluid dispensed in the pre-set tm is not detected until, for example, circuit boars are rjected at a later stage in thc manufacturing process, because the amount o variation has become unaccepLabie. Variations in the amount of adhesive dispensed in the pre-set time can arise for a number of reasons.These reasons include changes -p viscocity as the temperature rises or falls, or as the adhesive ages, and changes in pressure due to changes in the amount of adhesive actually in the syringe. The reject boards then have either to be scrapped, or the components mounted on them have to be salvaged, borh of which are expensive and wastefui of valuable materials and labour. It has been proposed in European Patent Application No. 314,012 to monit1or the dispensing of adhesive by inspecting the droplets of adhesive after they have been dispensed onto the circuit board.This has the disadvantage that if, for example, too much adhesive has been dispensed, it has already been deposited on the board, and corrective action must be taken.
It is an object of the present invenion to provide an improved system for monitorIng the operation of a dispensing nozzle for dispensing fluids, in which the above disadvantages are reduced or substantially obviated.
The invention provides a system for monitoring the operation of a dispensing nozzle for dispensing a fluid onto a surface, in which the amount of fluid dispensed is controlled by operating the nozzle for a pre-set time, characterised in that the system comprises
(a) means for inspecting the nozzle before the formation of a droplet ot rhe fluid on the nozzle, after the formation of this droplet and before it is discharged arid after the droplet has been discharged, in order to determine the amount of fluid present in the droplet and, optionally, other properties of the oroplet, and
(b) means for comparing the amount of fluid and, optionally, other properties of the aioplet, with standard values for these properties.
The inspection of the nozzle is preferably carried out optionally.
The optical inspection means preferably comprises a photo-sensitive diode on which a focussed image of t nozzle is created.
The optical inspection means may altsrnativiy comprise a television camera linked up to a pattern recognttion system. This arrangement has the advantage that it b able to give more detailed information ab to the shape of the droplet, but has the disadvantage that it is more expensive than the diode system, and takes up more space.
The invention further comprises a method of monitoring the operation of a nozzle for dispensing a fluid, characterised in that the nozzle is ir.specled before a droplet of the fluid is formed, it is inspected after a droplet is formed and before it is discharged, and it is inspected again after droplet discharge, and the results of they inspections are compared with standard results.
A preferred embodiment of a system according to the invention will cow be described with reference to the accompanying drawings, in which
Figure 1 is a view of the nozzle before droplet formation;
Figure 2 is a view of the nozzle after droplet formation;
Figure 3 is a schematic diagram of an embodiment of a monitoring system; and
Figure 4 s a view from above of an embodiment of a monitoring system.
As can be seen in Figures 1 and 2, a nozzle (2) is mounted on a syringe (not shown) containing adhesive to be dispensed. There is a residue (4) of adhesive from the previous droplet retained on the end of the nozzle (2). The nczzie (2) ;s arranged in front of a white surface (6), an inner area (8) of which comprises a photo-sensitive diode having square area which is uniformly sensitive to l--tgnt.
The shape o a droplet (10) formed on the nozzle (2) can be seen in Figure 2.
As is shown schematically in Figure 3, a light emitting diode (12) is used as the light source. h ltns (14) is provided to focus the light from the diode which then illuminates the nozzle (2). A second lens (16) is provided to focus the ~mage of ths nozzle (2) on to the light-sensitive area (8) of the photo diode.
The schematic system shown in Figure 3 would be too long for incorporation in, for example, a component placement system. Therefore, as shown in Figure 4 silvered prisms (18, 20) are provided to rotate the beams of light through 900 in order to provide a more compact arrangement.
The operation of the system will now be described with particular reference t the dispensing of an adhesive onto a circuit board.
In operation, the nozzle is inspected prior to the formation of a droplet, i.e. in the state shown in Figure 1, and the output voltage (V1) Of the pnoto-sensitive diode (8) is measured and recorded. This output voltage is proportional to tiie amount of light failing on the diode, which is itself relatad to the amount of adhesive on the nozzle. A droplet (10) is then allowed to form on the nozzle (2), and the output voltage (V2) is again measured and recorded.
Comparison of the cutput voltages V1 and V2 is used to determine the amount of change in tne dark area of the photo-sensitive diode, and hence the amount of fluid in the droplet. This change in output voltage is compared against the allowable range of changes in output voltage, to determine whether the amount of adhesive on the nozzle falls within acceptable limits. If it does, the nozzle is allowed to a~scharge the droplet in the correct position on the circuit board; if not, then the board is moved so tat the droplet can be deposited in its "scrap area", and the droplet formation cycle is started again.
In addition to cne montoring of individual droplets n order to decide whether a particular droplet of adhesive fails within an acceptable range of wolerances, the monitoring system can also be used t monitor trends in the amount of adhesive dispensed by the nozzle over a number cf successive operations. By monitoring such trends longer term effects such as changes in viscosity or dispensing characteristics as the syringe empties ca be identified and the dispensing time can be controlled to bring the dot size into acceptable tolerances.
After the nozzle has discharged its droplet, the output voltage (V3) of the photo-sensitive diode can again be measured and compared with the initial output voltage (V1) to determine whether all of the adhesive has been discharged onto the circuit board.
Claims (6)
1. A system for monitoring the operation of a dispensing nozzle for dispensing a fluid onto a surface, in which the amount of fluid dispensed is controlled by operating be nozzle for a pre-set time, charactersed in that the system comprises
(a) means for inspecting the nozzle before the formation of a droplet of the fluid on the nozzle, after the formation of this droplet and before rt It is discharged and after the droplet has been discharged, in order to determine the amount of fluid present in the droplet and, optionally, order properties of rhe droplet and
(b) means for ccmparing the amount of fluid and, optionally, other properties of the droplet, with standard values for these properties.
2. A system accord to claim 1, characterised in that the means for inspecting the nozzle comprises optical means.
3. A system according to olaim 2, characterised in that the optical inspection means comprises a photo-sensitive diode on which a focussed rage of the nozzle is created.
4. A system according to claim 2, characterised in that the optical inspection means comprises a releviston camera.
5. A method of monitoring the operation of a nozzle for dispensing a fluid, characterised in that the nozzle is inspected before a droplet of the fluid is formçd, it is inspected afrer a droplet is formed and before It is discharged, and it is inspected again after droplet discharge, and the results of these inspections are compared with standard results.
6. A monitoring system substantially as herein described, with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9119122A GB2259568A (en) | 1991-09-07 | 1991-09-07 | Monitoring fluid dispensing nozzle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9119122A GB2259568A (en) | 1991-09-07 | 1991-09-07 | Monitoring fluid dispensing nozzle |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9119122D0 GB9119122D0 (en) | 1991-10-23 |
| GB2259568A true GB2259568A (en) | 1993-03-17 |
Family
ID=10701046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9119122A Withdrawn GB2259568A (en) | 1991-09-07 | 1991-09-07 | Monitoring fluid dispensing nozzle |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2259568A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0641599A1 (en) * | 1993-09-08 | 1995-03-08 | Roche Diagnostics GmbH | Method and device for measuring the volume of liquids |
| DE19754459A1 (en) * | 1997-12-08 | 1999-06-17 | Max Planck Gesellschaft | Device and method for image recording on drop-generating dispensing heads |
| US6629397B1 (en) | 1997-12-04 | 2003-10-07 | Focke & Co. (Gmbh) | Machine monitoring apparatus capable of incorporation into a network |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102366435B1 (en) * | 2017-10-10 | 2022-02-23 | 반알엑스 파마시스템즈 인크. | Apparatus and method for monitoring and controlling the filling of containers with fluid medicaments in an aseptic environment |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1990001141A1 (en) * | 1988-07-21 | 1990-02-08 | Gebhard Birkle | A device for the contactless optical determination of the geometrical dimensions of an object by the shadow method |
| US4936828A (en) * | 1987-06-02 | 1990-06-26 | Kophu Chiang | Liquid drop image sensor |
-
1991
- 1991-09-07 GB GB9119122A patent/GB2259568A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4936828A (en) * | 1987-06-02 | 1990-06-26 | Kophu Chiang | Liquid drop image sensor |
| WO1990001141A1 (en) * | 1988-07-21 | 1990-02-08 | Gebhard Birkle | A device for the contactless optical determination of the geometrical dimensions of an object by the shadow method |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0641599A1 (en) * | 1993-09-08 | 1995-03-08 | Roche Diagnostics GmbH | Method and device for measuring the volume of liquids |
| US5856200A (en) * | 1993-09-08 | 1999-01-05 | Boehringer Mannheim Gmbh | Method and device for metering liquids |
| US6629397B1 (en) | 1997-12-04 | 2003-10-07 | Focke & Co. (Gmbh) | Machine monitoring apparatus capable of incorporation into a network |
| DE19754459A1 (en) * | 1997-12-08 | 1999-06-17 | Max Planck Gesellschaft | Device and method for image recording on drop-generating dispensing heads |
| US6851784B1 (en) | 1997-12-08 | 2005-02-08 | Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. | Method and device for recording an image on drop-producing dispensing heads |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9119122D0 (en) | 1991-10-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |