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US 4,303,342 AGranted
Method and apparatus for detecting foreign matters in liquids
AssigneeEisai Co., Ltd.
InventorToshio Takahashi
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AssigneeEisai Co., Ltd.
InventorToshio Takahashi
Estimating the term…
Method and apparatus for detecting foreign matters in liquids by irradiating light to a transparent container in which foreign matters are suspended and swirled together with the content liquid, and by measuring the change of transmitted light by individual units of a group of small light receivers. The change of transmitted light due to the displacement of the liquid surface is detected by the small light receivers, and the detection signals are taken up as DC components. In contrast, the change of transmitted light due to moving foreign matters is detected by the small light receivers, and the detection signals are taken up as AC components by means of capacitors. When the detection signal of the liquid surface is lower than the preset standard value, the small light receiver corresponding to the liquid surface is inhibited to issue an output, regardless of detection of foreign matters.
In an apparatus for detecting foreign matters in liquids by turning at a high speed a transparent container filled with a liquid, bringing the container to a standstill quickly, permitting suspended foreign matters to swirl with the liquid, illuminating the liquid and foreign matters, causing the transmitted light to be received by light receivers of a light detector provided in correspondence with the container, and measuring the change of incident light and transmitted light, the improvement which comprises the light receiver including an aggregate of small light receivers, each of said light receivers being connected to a corresponding unit of a first comparator group which compares the DC signal component obtained from the small light receivers with the standard value arbitrarily set as the signal level for detection of the liquid level to be excluded, each of said small light receivers being connected to a corresponding unit of a second comparator group which compares the AC signal component obtained from the small light receivers with the standard value set as the level for detection of foreign matters, said first comparator group and said second comparator group being connected to a corresponding AND circuit group, whereby said small light receivers are inhibited from issuing an output for judgement of rejection due to an output from one of said small light receivers which corresponds to the liquid surface.
In an apparatus for detecting foreign matters in liquids by turning at a high speed a transparent container filled with a liquid, bringing the container to a standstill quickly, permitting suspended foreign matters to swirl with the liquid, illuminating the liquid and foreign matters, causing the transmitted light to be received by light receivers of a light detector provided in correspondence with the container, and measuring the change of incident light and transmitted light, the improvement which comprises the light receiver including an aggregate of small light receivers, each of said small light receivers being connected to a corresponding amplifier for AC signal components, said amplifier for AC signal components being connected to a comparator group which compares the output of said amplifier with a standard value set according to the level for detection of foreign matters, and said small light receivers being connected to inhibiting diodes connected in parallel with said amplifiers for AC signal components.
In an improved method for detecting foreign matters in liquids by turning at a high speed a transparent container filled with a liquid, bringing the container to a standstill quickly, permitting the suspended foreign matters to swirl with the liquid, illuminating the liquid and foreign matters, causing the transmitted light to be received by light receivers of a light detector provided in correspondence with the container, and measuring the change of incident light and transmitted light, the improvement which comprises employing as said light receivers an aggregate of small light receivers, each receiver issuing an output signal for a judgement of rejection when the quantity of light received decreases below a certain standard level due to the movement of foreign matters, each receiver issuing an output signal for the liquid level when the quantity of light received decreases below a certain standard level due to the projection on the receiver of the swirling liquid surface formed by the rotation of the liquid, said liquid level signal preventing, for each small light receiver, said signal for a judgement of rejection from being transmitted to the succeeding output terminals.
Dependencies are inferred from the claim text.