JP7703504B2 - Pass Box - Google Patents

Description

The present invention relates to a pass box that is installed between a clean room where semiconductors, precision machinery, etc. are manufactured, food is processed, etc., and an antechamber or corridor, and is used to prevent dust from entering the clean room by allowing the exchange of goods while restricting the entry and exit of people.

There are pass boxes that are installed between the clean room and the anteroom or corridor, and are used to prevent dust from entering the clean room by restricting the entry and exit of people while allowing the exchange of goods. There are also pass boxes that use air jets to remove dust, pollen, etc. that have adhered to goods.

Patent Document 1 discloses an invention in which an inner box is used to separate the storage space for the items to be cleaned within a box connecting a low-cleanliness room and a high-cleanliness room, and jet air is sprayed into the inner box through a high-performance filter, in which a turntable is provided within the inner box on which the items are placed, and the turntable is rotated by a drive means.

JP2004-169951A

However, with this type of pass box, when the front room door is opened, contaminated air from the front room can flow into the warehouse, and when the clean room door is then opened, the air that flowed in can flow out into the clean room. Also, when an air jet is sprayed for a specified period of time on items being brought into the clean room to remove dust, there is a risk that an operator may accidentally open the door while the air jet is being sprayed, causing dust-containing air to flow into the clean room and resulting in insufficient removal of dust that has adhered to the items.

The object of the present invention is to address the above-mentioned issues and to reduce the outflow of dust into the clean room.

This is achieved by providing an exhaust fan in the pass box used to transfer items from the front room to the clean room, which exhausts the air inside the pass box to the front room.

This invention makes it possible to reduce the intrusion of dust into the clean room.

Problems, configurations and advantages other than those mentioned above will become clear from the description of the embodiments below.

FIG. 11 is an example of a front view of a pass box according to the first and second embodiments of the present invention, as viewed from the front room side. 2 is an example of a cross-sectional view of a pass box according to the first and second embodiments of the present invention taken along line AA' in FIG. 1 . FIG. 11 is a cross-sectional view of a display mechanism for indicating a door open state in the third embodiment of the present invention. FIG. 11 is a cross-sectional view of an indication mechanism for indicating a door unopenable state in the third embodiment of the present invention. FIG. 11 is a front view of a display mechanism for indicating a door open state in the third embodiment of the present invention. 13A and 13B are diagrams illustrating display contents of a display mechanism in the third embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. In each drawing for explaining the embodiment, the same components are given the same names and symbols as much as possible, and repeated explanations will be omitted.

Figure 1 is an example of a front view of a pass box in embodiment 1 of the present invention, seen from the antechamber side.

The pass box 1 is composed of an antechamber door 2, a clean room door 3, a floor 4, side walls 5 and 6 on both sides, and a ceiling 7, forming a pass box interior 8. An air jet mechanism 10 is installed on the ceiling 7, and is driven and controlled by a control unit (not shown) to spray air jets from an air jet nozzle 50. The floor 4 and side walls 5 and 6 are provided with holes such as punches or slits, and the air sprayed on the items 20 is exhausted through the holes.

Air that passes through the housing of the pass box 1 returns to the air jet mechanism 10 and circulates. The exhaust fan 11 is installed to exhaust a portion of the circulating air toward the front room side. This creates negative pressure inside the pass box. The control unit is installed to control the air jet mechanism and exhaust fan 11 of the pass box 1, and receives opening/closing information from the door switches 30, 31 of the front room side door 2 and the clean room side door 3, and controls the operation of the air jet mechanism 10 and the exhaust fan 11.

This control unit can be realized by a PLC (Programmable Logic Controller) or a microprocessor. The display board 12 is a nameplate that, for example, states "Open" or "Not Open", and the display can be switched by sliding left or right, providing the user with information on whether or not the pass box may currently be opened.

Next, the operation of the exhaust fan 11 will be described. Normally, the pass box 1 has three states: a standby state in which both doors are closed (including a state in which an item 20 is placed inside the pass box 8 and the air jet is not operating), a state in which only the front room side door 2 is open, and a state in which only the clean room side door 3 is open. The operation of the exhaust fan 11 in these three states will be described.

If both the front room door 2 and the clean room door 3 are open, the control unit may output an alarm because this is an abnormal state that may allow dust to enter the clean room, or may control the control unit so that the other door does not open while one of the doors is open.

In the standby state, the exhaust fan 11 is stopped. In this state, the pressure on the clean room side is kept higher than the pass box interior 8 and the front room side, so dust in the pass box interior 8 does not flow into the clean room side. However, after the front room door 2 is opened and closed, contaminated air remains in the pass box interior 8, so the exhaust fan 11 is operated for a certain period of time to clean the pass box interior 8.

When only the front room door 2 is open, the exhaust fan 11 is stopped. In this state, contaminated air from the front room side flows into the pass box interior 8, but because the pressure on the clean room side is kept higher than the pass box interior 8 and the front room side, dust from the pass box interior 8 does not flow out to the clean room side.

When only the clean room side door 3 is open, the exhaust fan 11 is in operation. Immediately after the front room side door 2 is opened or closed, there is contaminated air inside the pass box, so if the clean room side door 3 is opened in this state, the contaminated air will flow out into the clean room side. By operating the exhaust fan 11 in such a state, the contaminated air is exhausted to the front room side, and the inside of the pass box 8 can be cleaned by the air from the clean room side.

According to this embodiment, even if the front room door is opened and then the clean room door is opened, it is possible to prevent dust from leaking into the clean room.

Figure 2 is an example of a cross-sectional view of a pass box in an embodiment of the present invention taken along line AA' in Figure 1.

A pass box 1 is installed across a partition wall 51 that separates the clean room from the front room, and is equipped with a front room side door 2 and a cleaning room side door 3. By placing an item 20 placed through the front room side door 2 inside the pass box 8, it is possible to take it out through the clean room side door 3.

The front room side door 2 and the cleaning room side door 3 are each equipped with a handle 32, 33, which can be grasped to open the door. Each door is also equipped with a door switch 30, 31 that detects whether the door is open or closed and controls the operation of the exhaust fan 11 and the air jet mechanism 10. If the handles 32, 33 are equipped with a locking mechanism that operates based on information from the door switches 30, 31 to prevent the door from being opened accidentally when the air jet mechanism 10 is operating, sufficient cleaning of the items 20 can be achieved.

If a locking mechanism were to be installed on the door to lock it when the air jet is operating, the structure of the pass box would become complicated. Therefore, the control unit operates the exhaust fan 11 while the air jet is operating. By operating the exhaust fan 11 during the air jet, the pressure inside the pass box 8 decreases, making it difficult to open the doors on both sides.

By making the door harder to open, even if the door is not provided with a locking mechanism, it is possible to prevent the door from being opened accidentally during air jet application, and the air jet can be applied to the item 20 for a predetermined period of time.
According to this embodiment, the door cannot be opened while the air jet is in operation, and the air jet can be directed at the article for a predetermined period of time.

Figures 3(a) to (c) show the mechanism for switching the display of the pass box display mechanism 12 in the third embodiment of the present invention.

If it is decided that an air jet will be directed at the items for a certain period of time to ensure that dust is removed from the pass box, it is desirable to provide a mechanism to prevent the door from being opened within the certain period of time, for example, a display mechanism 12 that switches between displaying a sign saying "open" or "not open" depending on the state of the pass box. In order to switch the display, it is necessary to provide a mechanism to move the display sign, and this mechanism can be composed of parts such as the syringe and plunger of a syringe, and the display of the display mechanism 12 can be switched by moving the display linked to the plunger using the negative pressure action of the exhaust fan 11.

Although an electrical mechanism can be used to switch the display, a simple configuration can be used to alert the user to the current status of the pass box by switching the display board using an actuator that uses a syringe and plunger.

Figure 3(a) is a cross-sectional view of the display panel in the door open state in the third embodiment of the present invention.

In this state, there is no negative pressure inside the pass box, so the spring 42 contracts, the second display plate 46 moves to the left, and the display mechanism 12 displays the first display plate 45, indicating that the door can be opened. The syringe 40 and plunger 44 may be made of a low-friction material to prevent dust from being generated by friction. Furthermore, by using a material with low friction, it becomes possible to switch the display plate even when the pressure difference between the inside of the pass box and the antechamber is small. Examples of low-friction materials include fluororesin and plastic with a glass sheet attached.

Figure 3(b) is a cross-sectional view of the display panel in the door-opening disabled state in the third embodiment of the present invention.

In this state, the pressure difference between the negative pressure inside the pass box and the pressure in the front room through the vent causes the plunger 44 to move to the right against the tension of the spring 42, and a second display plate 46 is displayed on the display mechanism 12, indicating that the door cannot be opened.

Figure 3(c) is a front view of the display mechanism 12 in the door open state in the third embodiment of the present invention. When the door is open, the first display plate 45 is displayed on the display mechanism 12.

Figure 3(d) is a diagram showing the display contents of the display board in the third embodiment of the present invention. The first display board 45 displays "Openable" to indicate that the door can be opened (openable state), and the second display board 46 displays "Cannot open" to indicate that the door cannot be opened (cannot be opened).

This embodiment allows the user to be alerted of the current status of the pass box with a simple configuration.

1 Pass box, 2 Front room side door, 3 Clean room side door, 4 Floor, 5, 6 Side wall, 7 Ceiling, 10 Air jet mechanism, 11 Exhaust fan, 12 Display mechanism, 20 Item, 30, 31 Sensor, 32, 33 Handle, 40 Syringe, 42 Spring, 44 Plunger, 43 Vent, 45 First display plate, 46 Second display plate, 51 Partition wall

Claims (3)

In a pass box used for transferring items from the front room side to the clean room side, an exhaust fan is provided to exhaust air from the pass box to the front room side ,
A pass box equipped with a control unit that controls the operation and stopping of the exhaust fan based on the open/close state of the front room door, the open/close state of the clean room door, and the operating state of the air jet, and operates the exhaust fan when the clean room door is open . The pass box according to claim 1 ,
The control unit is a pass box that controls the operation of the exhaust fan when the air jet is operating. In a pass box used for transferring items from the front room side to the clean room side, an exhaust fan is provided to exhaust air from the pass box to the front room side,
a control unit that controls the operation and stop of the exhaust fan based on the open/closed state of the front room door, the open/closed state of the clean room door, and the operating state of the air jet, and a display panel that indicates whether the door can be opened or not;
A pass box having an actuator with a syringe and a plunger that changes the display on the sign to one indicating that the sign should not be opened due to the negative pressure generated when the exhaust fan is operated.

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