JPS6270725A - Apparatus for detecting pinhole or the like in hermetically sealed food - Google Patents

Abstract

PURPOSE:To certainly inspect the pinhole and seal inferiority of hermetically sealed food during its running on a belt, by applying high frequency high voltage between the metal plate arranged in close vicinity to the under surface of the belt and a brush electrode arranged so as to be contacted with the seal surface of the hermetically sealed food above the belt. CONSTITUTION:An inspection belt conveyor 4 comprises the belt 8 trained over belt wheels 6, 7 and the belt 8 comprises a porous insulating material. A metal plate 9 is provided so as to be almost contacted with the under surface of the belt 8 in the feed side thereof and a brush electrode 10 is provided above the belt 8 so as to cross the moving direction of the belt 8 at a right angle. High frequency high voltage is applied between the metal plate 9 and the electrode 10. When hermetically sealed food (soybean curd) 1 is fed to the direction shown by an arrow A on a conveyor 4, the electrode is contacted with the seal surface of the soybean curd 1 and the presence of a pinhole and seal inferiority is detected on the basis of the presence of the generation of flashover.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device for detecting seal defects, pinholes, etc. in a sealed food product in which a food product such as tofu is placed in a container and sealed with a film or the like.

For low-priced foods such as Tofu sold in the Song Dynasty and Bisama, the containers themselves were made with low m-values, and as a result, pinholes and poor seals were more noticeable. This is the current situation. However, if pinholes and poor sealing are left unaddressed, for example, tofu that has been blow-filled into a container may be contaminated with bacteria or outside air, causing deformation due to swelling and discoloration of the tofu. In addition, there were other problems with Kak1~Tofu, such as water rupture and leaving the sales floor dirty.

For this reason, in the past, checks for pinholes, seal defects, etc. were carried out manually, but most of the inspections were done by spot inspection, and checks were done visually or by touch, and it was not possible to inspect all tofu. In fact, it was impossible. In addition, there was also the problem that pinholes and seal defects (small dents) could not be detected visually.

The present invention solves the above problem by providing a belt made of an insulator that is wound around at least two belt pulleys, and a belt that is placed close to the lower surface of the conveying side of the belt. a first test electrode made of a conductive plate, and a second test electrode disposed above the conveyance side of the belt so as to be in contact with the entire sealed surface of the sealed food; This problem was solved by applying a high-frequency, high-voltage voltage between the first test electrode and the second test electrode.

Embodiments of the present invention will now be described with reference to the accompanying drawings.

First, the detection principle for detecting pinholes and seal defects will be explained using FIGS. 1 to 3.

In FIG. 1, a tofu 1 housed in an insulating container and sealed with an insulating film etc. is placed on an electrode A with a small surface area.
When a high-frequency, high-voltage AC voltage V is applied to the ground electrode B, which has a large surface area, the electrical equivalent circuit becomes as shown in FIG. In the figure, ■ is the applied voltage C1, the capacitance between electrode A and the tofu, C2, the capacitance container R between electrode B and the tofu, and the electrical resistance of the tofu, 11, which flows through the circuit when the inspected product is non-defective. It is a minute current.

In this case, since the surface areas of the two opposing ff1tIA and B are different, the electrostatic amount of C2 is larger than that of C1. Therefore, when using a high frequency AC power source, the impedance of C2 can be ignored compared to C1 and R, and the equivalent circuit can be approximately regarded as a series circuit of C1 and R as shown in Figure 3. be able to.

Therefore, the power supply voltage V is set at a voltage such that if there is a pinhole or a poor seal in the tofu 1, a flashover will occur in the discharge gap C, but if there is no pinhole or the like, no flashover will occur. Then, when tofu 1 is fed between electrodes Δ and B, a flashover occurs when a pinhole or the like comes to a position opposite electrode A, and a discharge current T2 flows through the circuit. If there are no pinholes or the like in tofu 1, flashover will not occur, so minute currents I and L based on C1, which functions as a capacitor, will not flow. Therefore, by measuring the current flowing through the circuit, it is possible to determine whether there is a pinhole or the like.

This method has many advantages, such as being able to detect pinholes as small as 0.5 microns or less and poor seals, and having no effect on the shigamo tofu itself.

However, when using this method, it is necessary to sequentially pass a large amount of tofu between opposing electrodes A and B in a short period of time. The inventor of the present invention has discovered that pinholes and seal defects can be detected while tofu is placed on a belt and the belt is running. in this case,
The belt is used as the electrode B, and the electrode A is a brush electrode.

However, the belt is fa! In the case of @B, it is advantageous in that it has a large surface area, but an expensive metal belt must be used, which inevitably increases the cost.

Furthermore, if the running belt is an electrode, the method of energizing the belt becomes complicated, resulting in high costs.

Therefore, the inventor of the present invention has devised a detection device shown in FIGS. 11 to 6, which will be described in detail.

In FIG. 4, the detection device 2 includes an incoming belt conveyor 3.
, an inspection belt conveyor 4, and a discharge belt conveyor 5 are provided so that their conveying surfaces are horizontal. The inspection belt conveyor 4 consists of an endless belt 8 wound around a belt wheel 6.7, and the belt 8 is made of an insulator.
And a porous belt is used. Further, the belt 8 does not need to be a porous belt as long as it is a thin belt. A first test electrode configured as a conductive metal plate 9 is arranged so as to be substantially in contact with the lower surface of the belt 8 on the conveying side. As shown in FIGS. 4 to 6, this metal plate 9 has a length that overlaps almost the entire length of the running side of the belt 8, and a width that is wider than the width of the belt 8. Also, belt 8
A brush ff1tll is provided above the belt 8 so as to be perpendicular to the moving direction of the belt 8.

A second test electrode is provided which is configured as a.

In this case, the lower end of the brush electrode 10 is placed so that when the tofu arrives, the lower end of the brush electrode 10 touches the upper surface of the tofu as shown in the figure.

The discharge belt conveyor 5 is mounted on a cylinder 11 so as to be swingable between the position shown by the solid line and the position shown by the chain line.

In the detection device configured as described above, when the tofu 1 is placed on the carry-in bell 1 to the conveyor 3, the tofu l moves in the direction indicated by the arrow and is conveyed onto the inspection belt conveyor 4. Then, as the inspection belt conveyor 4 runs, the tofu 1 comes to the inspection position where it touches the brush electrode 10. here,
The gold plate 9 corresponds to the electrode B having a large surface area, and the brush electrode 10 corresponds to the electrode A having a small surface area, and a high frequency high voltage is applied between both electrodes. At this time.

Since the belt 8 is porous, electric discharge occurs in that part, and the presence or absence of pinholes and seal defects at the position where the brush electrode 10 of the tofu 1 touches is detected. In addition, if the belt is not porous, it is 1 if the belt is thin. Since it becomes like a capacitor with a large rI capacitance and can be ignored in practice, pinholes and the like can be detected.

In this manner, by providing the large gold/aFi, 9 electrode and the brush electrode IO under the belt 8, the presence or absence of pinholes and seal defects in the bean/& can be inspected without any trouble. Furthermore, the metal plate 9 also serves as a support for the belt 8.

In this way, the tofu l according to the present invention is sequentially inspected, and if the tofu is good without pinholes etc., it is moved in the direction of the arrow by the discharge belt conveyor 5, and if it is defective, the discharge belt conveyor 5 is moved. It moves to the position of the chain and line and is dropped in the direction of arrow B, automatically classifying good products and defective products.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. For example, the inspection belt conveyor 4 may be provided with three or more belt pulleys and may be wound around the belt pulleys, and the 21i! 2
The scanning electrode is not limited to a brush electrode, but may be a conductive rubber plate or the like.

As described above, the present invention can reliably inspect sealed foods such as tofu for pinholes and seal defects while traveling on a belt conveyor, and can also inspect large quantities in a short period of time. can.

Therefore, it was possible to prevent the delivery of defective products, and high reliability was obtained.

4. [Side 21 (7) u Qi Explanation FIGS. 1 to 3 are circuit diagrams showing the principle of a method for detecting pinholes and the like by the high frequency high voltage method, and FIG. 4 is a plan view.

1... Tofu 4... Inspection belt conveyor 6.7... Belt car 8... Belt 9... Metal plate
10... Brush electrode Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a detection device that detects pinholes, seal defects, etc. in a sealed food whose container opening is sealed with a thin film material after the food is inserted into a container, the device is wrapped around at least two belt pulleys and is made of an insulating material. a first belt made of a conductive plate placed close to the lower surface of the belt on the conveying side;
A test electrode, and a second test electrode arranged above the conveyance side of the belt so as to be in contact with the entire sealed surface of the sealed food, wherein the first test electrode and the second test electrode The detection device is characterized in that a high-frequency, high-voltage voltage is applied during the period. (2) The detection device according to claim 1, wherein the second test electrode is a linear brush electrode arranged to intersect with the running direction of the belt.