CN220077697U - PCB board direction discernment adjustment structure and conveyor - Google Patents

Abstract

The utility model provides a PCB board direction identification and adjustment structure and a conveying device, which include a controller. The controller is electrically connected to an X-ray detection device, a first conveying component, and a flip plate component respectively; the X-ray detection device , the first conveying component and the flipping component are arranged in sequence along the conveying direction; a first reversing mechanism is provided above the first conveying component, and the first reversing mechanism includes a first rotating plate and a first rotating driving member that are connected in sequence. , the first lifting assembly, the first rotating plate is provided with a vacuum suction cup; the flipping assembly includes a flipping frame and a flipping motor, the flipping motor is connected to the flipping frame, and upper transmission belts are arranged at intervals on the flipping frame. The lower conveyor belt, the upper conveyor belt and the lower conveyor belt form a conveyor channel for accommodating the PCB board. The utility model can identify and adjust the direction of the PCB board to ensure that the PCB board is conveyed to the subsequent processing equipment in the correct manner.

Description

A PCB board direction identification and adjustment structure and conveying device

Technical field

The utility model relates to the technical field of PCB processing, and in particular to a PCB board direction identification and adjustment structure and a conveying device.

Background technique

PCB (Printed Circuit Board), the Chinese name is printed circuit board, also known as printed circuit board. It is an important electronic component, a support for electronic components, and a carrier for electrical interconnection of electronic components. PCB is one of the important components of the electronics industry. Almost every electronic device, as long as it has electronic components such as integrated circuits, uses printed boards to electrically interconnect the various components. Printed circuit boards can replace complex wiring and realize electrical connections between components in the circuit. It not only simplifies the assembly and welding of electronic products, reduces the wiring workload in traditional ways, and greatly reduces the labor intensity of workers; it also reduces the It reduces the overall size of the machine, reduces product costs, and improves the quality and reliability of electronic equipment.

Printed circuit boards have good product consistency and can adopt standardized designs, which is conducive to mechanization and automation in the production process. At the same time, the entire printed circuit board that has been assembled and debugged can be used as an independent spare part to facilitate the interchange and maintenance of the entire machine. At present, printed circuit boards have been extremely widely used in the production and manufacturing of electronic products.

During the production process of PCB boards, it is necessary to ensure the correct processing direction. In the existing technology, it is difficult to distinguish the forward and reverse directions and the front and rear directions of the PCB board. During the transportation of the PCB board, it often happens that the PCB board is sent to the processing device in the wrong direction, causing the processing device to be unable to process the PCB board. The processing efficiency may cause the processing device to directly process the PCB board with the wrong orientation, causing the product to be defective or even scrapped.

Utility model content

In order to overcome the problems existing in related technologies, the present invention provides a PCB board direction identification and adjustment structure and a conveying device, which can identify and adjust the direction of the PCB board to ensure that the PCB board is conveyed to subsequent processing equipment in a correct manner.

One of the purposes of the present utility model is to provide a PCB board direction recognition and adjustment structure, including a controller, the controller is electrically connected to the X-ray detection device, the first conveying component, and the flipping component respectively; the X-ray The detection device, the first conveying component, and the flipping component are arranged in sequence along the conveying direction; a first reversing mechanism is provided above the first conveying assembly, and the first reversing mechanism includes a first rotating plate, a first rotating plate, and a first rotating plate connected in sequence. The driving part and the first lifting component, the first rotating plate is provided with a vacuum suction cup; the flipping plate assembly includes a flipping frame and a flipping motor, the flipping motor is connected to the flipping frame, and upper transmission is arranged at intervals on the flipping frame. The upper conveyor belt and the lower conveyor belt form a conveyor channel to accommodate the PCB board.

In a preferred technical solution of the present invention, the X-ray detection device includes a mounting plate, an X-ray emitter, and an X-ray receiver. The X-ray emitter and the X-ray receiver are installed on the mounting plate at intervals up and down. Installed on the moving end of the traversing component, the mounting plate is driven by the traversing component to move perpendicular to the conveying direction.

In a preferred technical solution of the present invention, two X-ray detection devices are symmetrically arranged.

In a preferred technical solution of the present invention, the upper conveyor belt and the lower conveyor belt are both roller conveyors, and the turning frame is provided with pressure plate assemblies above the upper conveyor belt and below the lower conveyor belt; The pressure plate assembly includes a vertical pressure plate cylinder located at the gap between adjacent conveyor rollers of the roller conveyor. A pressure block is installed at the end of the cylinder rod of the pressure plate cylinder, and the pressure block faces the conveying channel.

In a preferred technical solution of the present invention, a transplanting component is provided on the input side of the X-ray detection device; the transplanting component includes a transplanting plate, and a vacuum suction cup is provided on the transplanting plate; The plate is installed on the moving end of the longitudinal shift component via a lifting mechanism.

In a preferred technical solution of the present invention, a second conveying assembly is provided on the input side of the transplanting assembly, a centering mechanism is installed on the second conveying assembly, and a centering plate of the centering mechanism is installed on the centering plate. Induction probe; the second conveying component, centering mechanism, and induction probe are all electrically connected to the controller.

In a preferred technical solution of the present invention, a second reversing mechanism is provided above the second conveying component. The second reversing mechanism includes a second rotating plate, a second rotating driving member, and a second rotating plate connected in sequence. Lifting assembly, a vacuum suction cup is provided on the second rotating plate.

In a preferred technical solution of the present invention, the second conveying component is provided with an escape opening for giving way to the transplanting component, and the transplanting component is arranged in the escape opening.

The second object of this utility model is to provide a conveying device.

In a preferred technical solution of the present invention, the conveying device includes a frame, and the above-mentioned PCB board direction identification and adjustment structure is installed on the frame.

In a preferred technical solution of the present invention, a protective cover is installed on the frame, the PCB board direction identification and adjustment structure is located in the protective cover, and an observation window and a switch door are provided on the protective cover.

Because the conveying device adopts the above-mentioned PCB board direction identification and adjustment structure, it can identify and adjust the direction of the PCB board during the conveying process to ensure that the PCB board is conveyed to subsequent processing equipment in the correct manner.

The beneficial effects of this utility model are:

The utility model provides a PCB board direction identification and adjustment structure that obtains the direction mark on the PCB board through an X-ray detection device, and the controller determines the orientation of the PCB board based on the obtained direction mark; the PCB board with the wrong direction of the first reversing mechanism Perform 180-degree reversal; the flipping component can flip and redirect the PCB board with the wrong direction; through the cooperation of the X-ray detection device, conveyor component, flipping component, reversing mechanism, and controller, the direction of the PCB board can be realized Identify and adjust to ensure that PCB boards are delivered to subsequent processing equipment in the correct manner.

The utility model also provides a conveying device including the above-mentioned pre-tightening force adjusting device, which can identify and adjust the direction of the PCB board during the conveying process to ensure that the PCB board is conveyed to subsequent processing equipment in a correct manner.

Description of drawings

Figure 1 is a schematic diagram of the PCB board direction identification and adjustment structure.

Figure 2 is a schematic diagram of the PCB board direction recognition and adjustment structure.

Figure 3 is a schematic diagram of the PCB board direction recognition and adjustment structure applied to the conveyor device.

Reference signs:

A-frame; B-shield; 100-X-ray detection device; 110-X-ray emitter; 120-X-ray receiver; 130-mounting plate; 140-traverse component; 200-first conveying component; 300 -Flip plate assembly; 310-flip motor; 320-flip frame; 330-upper transmission belt; 340-lower transmission belt; 350-pressure plate cylinder; 360-pressure block; 400-first reversing mechanism; 410-first rotation Plate; 420-first rotary driving member; 430-first lifting component; 500-vacuum suction cup; 600-transplanting component; 610-transplanting plate; 620-lifting mechanism; 630-longitudinal shift component; 700-second conveying Components; 710-centering mechanism; 800-second reversing mechanism; 810-second rotating plate; 820-second rotating drive member; 830-second lifting component; 900-longitudinal shift linear module.

Detailed ways

Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The terminology used in the present invention is for the purpose of describing specific embodiments only and is not intended to limit the present invention. As used in this disclosure and the appended claims, the singular forms "a," "the" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms "first", "second", "third", etc. may be used in the present invention to describe various information, the information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, the first information may also be called second information, and similarly, the second information may also be called first information. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically limited.

Printed circuit boards have good product consistency and can adopt standardized designs, which is conducive to mechanization and automation in the production process. At the same time, the entire printed circuit board that has been assembled and debugged can be used as an independent spare part to facilitate the interchange and maintenance of the entire machine. At present, printed circuit boards have been extremely widely used in the production and manufacturing of electronic products.

During the production process of PCB boards, it is necessary to ensure the correct processing direction. In the existing technology, it is difficult to distinguish the forward and reverse directions and the front and rear directions of the PCB board. During the transportation of the PCB board, it often happens that the PCB board is sent to the processing device in the wrong direction, causing the processing device to be unable to process the PCB board. The processing efficiency may cause the processing device to directly process the PCB board with the wrong orientation, causing the product to be defective or even scrapped.

Example 1

In response to the above problems, Embodiment 1 provides a PCB board direction identification and adjustment structure, which can perform direction identification and adjustment on the PCB board to ensure that the PCB board is transported to subsequent processing equipment in a correct manner.

As shown in Figures 1 and 2, a PCB board direction recognition and adjustment structure includes a controller, which is electrically connected to the The detection device 100 is used to scan the PCB board to obtain the direction mark, and the first conveying component 200 is used to send the PCB board to the flipping component 300;

The X-ray detection device 100, the first conveying component 200, and the flipping component are arranged in sequence along the conveying direction;

A first reversing mechanism 400 is provided above the first conveying assembly 200. The first reversing mechanism 400 is used to perform 180-degree reversing of the PCB board; the first reversing mechanism 400 includes first rotating plates connected in sequence. 410. The first rotating drive part 420 and the first lifting assembly 430. The first rotating plate 410 is provided with a vacuum suction cup 500; the flipping assembly 300 includes a flipping frame 320 and a flipping motor 310. The flipping motor 310 is connected to The flip frame 320 has an upper conveyor belt 330 and a lower conveyor belt 340 spaced apart on the flip frame 320. A conveying channel for accommodating PCB boards is formed between the upper conveyor belt 330 and the lower conveyor belt 340; for example, the flip frame 320 is installed on the output shaft of the flip motor 310.

For example, in practical applications, the first reversing mechanism 400 is installed on the longitudinal shift linear module 900 .

For example, in practical applications, the first conveying component 200 is a conveyor, preferably a roller conveyor, the first rotating driving component 420 is a rotating cylinder or a rotating motor, and the first lifting component 430 is a linear module or a cylinder.

In this embodiment, the X-ray detection device 100 includes a mounting plate 130, an X-ray emitter 110, and an X-ray receiver 120. The X-ray emitter 110 and the X-ray receiver 120 are installed on the mounting plate 130 at intervals up and down. The mounting plate 130 is installed at the moving end of the traversing assembly 140. The mounting plate 130 is driven by the traversing assembly 140 and moves perpendicular to the conveying direction. Through the traversing assembly 140, the mounting plate can be extracted according to the size of the PCB board before conveying, and the mounting plate can be adjusted accordingly. 130 to ensure that the X-ray detection device 100 can obtain the direction mark.

For example, in practical applications, the traverse component 140 adopts a linear module.

In this embodiment, two X-ray detection devices 100 are arranged symmetrically to scan the left and right sides of the PCB board simultaneously to obtain the direction marks.

For example, in practical applications, a direction mark is provided on the surface or inside of the PCB board, and the direction mark is set on the left or right side of the center line of the length direction of the PCB board; during the transportation process, first, the PCB board is transported in a preset direction During the process of entering the first conveying assembly 200, the left and right sides of the PCB board are detected by the X-ray detection device 100 to obtain the direction identification; then, the controller determines whether a 180-degree reversal and/or flipping is required according to the direction identification; if not If a 180-degree reversal and flipping is required, the PCB board direction is correct, and the PCB board has passed through the first conveying assembly 200 and the flipping assembly 300 and then is output to the subsequent processing device; if the PCB board needs to be 180-degree reversing, the PCB board has been The first conveying assembly 200 is transported to the first reversing station directly below the first reversing mechanism 400. The first lifting assembly 430 drives the first rotating plate 410 to move downward and absorbs the PCB board through the vacuum suction cup 500. Subsequently, the first lifting assembly 430 The assembly 430 drives the first rotating plate 410 to move upward, and the first rotating driving member 420 drives the first rotating plate 410 to rotate 180 degrees to complete the 180-degree reversal of the PCB board. After the reversal, the first lifting assembly 430 drives the first rotating plate. 410 moves down and places the PCB board on the first conveying component 200. The empty suction cup no longer adsorbs the PCB board, and the changed PCB board is sent to the conveying channel of the flipping component by the first conveying component 200; if the PCB board needs to be flipped and redirected, , then the flipping motor 310 drives the flipping frame 320 to rotate 180 degrees to realize the flipping of the PCB board backward and output the PCB board.

For example, in practical applications, the controller determines that the direction of the PCB board is wrong based on whether it matches the direction mark detected by the X-ray detection device 100 on the preset side; if the direction mark is not obtained on the preset side, it determines that the PCB board is in the wrong direction. The direction is wrong and you need to rotate 180 degrees; if the preset side does not obtain the direction identification, you do not need to rotate 180 degrees; if the preset side does not obtain the direction identification, rotate the obtained direction identification 180 degrees at this time. Comparing with the standard graphic, the controller determines the direction of the PCB board based on whether the shape of the detected direction mark can coincide with the standard graphic; if it cannot overlap, it means that the direction of the PCB board is wrong. At this time, it is judged that the direction of the PCB board is wrong. You need to Flip; if the shape of the detected mark can coincide with the standard graphic, it is judged that the orientation of the PCB board is correct.

In one embodiment, the upper conveyor belt 330 and the lower conveyor belt 340 are both roller conveyors, and the turning frame 320 is provided with pressure plate assemblies above the upper conveyor belt 330 and below the lower conveyor belt 340; so The pressure plate assembly includes a vertical pressure plate cylinder 350. The pressure plate cylinder 350 is located at the gap between adjacent conveying rollers of the roller conveyor. A pressure block 360 is installed at the end of the cylinder rod of the pressure plate cylinder 350. The pressure block 360 Toward the conveying channel; when it needs to be turned over, the pressing plate cylinder 350 drives the pressing block 360 to press the PCB board firmly, thereby preventing the PCB board from coming out of the conveying channel during the turning process.

In one embodiment, in order to realize automatic loading, a transplanting assembly 600 is provided on the input side of the X-ray detection device 100; the transplanting assembly 600 includes a transplanting plate 610, and the transplanting plate 610 is provided with a Vacuum suction cup 500; the transplanting plate 610 is installed on the moving end of the longitudinal movement assembly 630 through the lifting mechanism 620; when transplanting is required, the lifting mechanism 620 drives the transplanting plate 610 to move to the PCB board, and the transplanting plate 610 passes through the vacuum suction cup 500 adsorbs the PCB board, and then the longitudinal movement component 630 drives the transplanting plate 610 to send the PCB board to the first conveying component 200. During the conveying process, the PCB board will pass through the X-ray detection device 100. At this time, the X-ray detection device 100 board for testing.

For example, in practical applications, the longitudinal movement component 630 is a linear module, and the lifting mechanism 620 is a linear module or a cylinder.

In this embodiment, a second conveying assembly 700 is provided on the input side of the transplanting assembly 600. A centering mechanism 710 is installed on the second conveying assembly 700. A centering plate of the centering mechanism 710 is mounted on the centering plate. Induction probe; the second conveying component 700, the centering mechanism 710, and the induction probe are all electrically connected to the controller.

For example, in practical applications, the centering mechanism 710 adopts a centering structure well known in the art. The centering mechanism 710 includes two centering plates symmetrically arranged on both sides of the conveying direction. The two centering plates are formed by the same centering plate. The two-way telescopic part or two different one-way telescopic parts are driven to move toward or away from each other.

For example, in practical applications, a centering mechanism 710 may also be added at the first reversing station.

In this embodiment, a second reversing mechanism 800 is provided above the second conveying assembly 700. The second reversing mechanism 800 includes a second rotating plate 810, a second rotating driving member 820, and a second rotating plate 810 connected in sequence. Lifting assembly 830, a vacuum suction cup 500 is provided on the second rotating plate 810.

For example, in practical applications, the second conveying component 700 is a conveyor, preferably a roller conveyor, the second rotating driving component 820 is a rotating cylinder or a rotating motor, and the second lifting component 830 is a linear module or a cylinder.

In this embodiment, the middle part of the output side of the second conveying component 700 and the middle part of the input side of the first conveying component 200 are provided with escape openings to make way for the transplanting component 600, and the transplanting component 600 is disposed in the escape openings. .

For example, in practical applications, the PCB board needs to be transported with its long side perpendicular to the conveying direction. When the PCB board is sent to the centering detection position through the second conveying component 700, if the sensing probe does not move after the centering mechanism 710 is moved in place, is triggered, the controller determines that the position of the PCB board is wrong, and at this time it is in a state where the short side is perpendicular to the conveying direction; at this time, the second reversing mechanism 800 moves to perform a 90-degree reversal of the PCB board, and the second reversing mechanism 800 moves The action principle of is the same as that of the first reversing mechanism 400 and will not be described again here.

This PCB board direction recognition and adjustment structure obtains the direction mark on the PCB board through the Reversing; the flipping assembly 300 can flip and redirect the PCB board with the wrong orientation; through the cooperation of the X-ray detection device 100, the conveying component, the flipping assembly 300, the reversing mechanism, and the controller, the orientation of the PCB board can be realized Identify and adjust to ensure that PCB boards are delivered to subsequent processing equipment in the correct manner.

Example 2

This embodiment only describes the differences from Embodiment 1, and other technical features are the same as the above-mentioned embodiment. Further, the PCB board direction recognition and adjustment structure in Embodiment 1 is applied to the conveyor device.

As shown in Figure 3, the conveying device includes a frame A, and the PCB board direction identification and adjustment structure in Embodiment 1 is installed on the frame A.

In this embodiment, a protective cover B is installed on the rack A. The PCB board direction identification and adjustment structure is located in the protective cover B. The protective cover B is provided with an observation window and a switch door.

In this embodiment, because the conveying device adopts the PCB board direction identification and adjustment structure in Embodiment 1, it can identify and adjust the direction of the PCB board during the conveying process to ensure that the PCB board is conveyed to the subsequent processing equipment in a correct manner.

The relative arrangement of components and steps, numerical expressions, and numerical values set forth in these examples do not limit the scope of the application unless specifically stated otherwise. At the same time, it should be understood that, for convenience of description, the dimensions of various parts shown in the drawings are not drawn according to actual proportional relationships. Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the authorized specification. In all examples shown and discussed herein, any specific values are to be construed as illustrative only and not as limiting. Accordingly, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters refer to similar items in the following figures, so that once an item is defined in one figure, it does not need further discussion in subsequent figures. In the description of this application, it should be understood that directional words such as "front, back, up, down, left, right", "horizontal direction, vertical direction, vertical, horizontal" and "top, bottom" indicate The orientation or positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description. Without explanation to the contrary, these positional words do not indicate or imply the device or device referred to. Components must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the scope of the present application; the orientation words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

For the convenience of description, spatially relative terms can be used here, such as "on...", "on...", "on the upper surface of...", "above", etc., to describe what is shown in the figure. The spatial relationship between one device or feature and other devices or features. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a feature in the figure is turned upside down, then one feature described as "above" or "on top of" other features or features would then be oriented "below" or "below" the other features or features. under other devices or structures". Thus, the exemplary term "over" may include both orientations "above" and "below." The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In addition, it should be noted that the use of words such as "first" and "second" to define parts is only to facilitate the distinction between corresponding parts. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood. To limit the scope of protection of this application.

The above descriptions are only preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, the present utility model may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (10)

1. The utility model provides a PCB board direction discernment adjustment structure, includes controller, its characterized in that: the controller is respectively and electrically connected with the X-ray detection device, the first conveying assembly and the turning plate assembly;

the X-ray detection device, the first conveying component and the overturning component are sequentially arranged along the conveying direction;

a first reversing mechanism is arranged above the first conveying assembly and comprises a first rotating plate, a first rotating driving piece and a first lifting assembly which are sequentially connected, and a vacuum chuck is arranged on the first rotating plate;

the turnover plate assembly comprises a turnover frame and a turnover motor, wherein the turnover motor is connected with the turnover frame, an upper conveying belt and a lower conveying belt are arranged on the turnover frame at intervals, and a conveying channel for accommodating a PCB board is formed between the upper conveying belt and the lower conveying belt.

2. The PCB board direction recognition adjustment structure of claim 1, wherein:

the X-ray detection device comprises a mounting plate, an X-ray emitter and an X-ray receiver, wherein the X-ray emitter and the X-ray receiver are mounted on the mounting plate at intervals up and down, the mounting plate is mounted at the moving end of the transverse moving assembly, and the mounting plate is driven by the transverse moving assembly to move perpendicular to the conveying direction.

3. The PCB board direction recognition adjustment structure of claim 2, wherein:

the X-ray detection devices are symmetrically arranged in two.

4. The PCB board direction recognition adjustment structure of claim 1, wherein:

the upper conveying belt and the lower conveying belt are roller conveyor, and the turning frame is provided with pressing plate components above the upper conveying belt and below the lower conveying belt;

the pressing plate assembly comprises a vertically arranged pressing plate air cylinder, the pressing plate air cylinder is located at a gap between adjacent conveying rollers of the roller conveyor, a pressing block is mounted at the tail end of an air cylinder rod of the pressing plate air cylinder, and the pressing block faces the conveying channel.

5. The PCB board direction recognition adjustment structure of claim 1, wherein: the input side of the X-ray detection device is provided with a transplanting assembly;

the transplanting assembly comprises a transplanting plate, and a vacuum chuck is arranged on the transplanting plate;

the transplanting plate is arranged at the moving end of the longitudinal moving assembly through the lifting mechanism.

6. The PCB board direction identification adjustment structure of claim 5, wherein:

the input side of the transplanting assembly is provided with a second conveying assembly, a centering mechanism is arranged on the second conveying assembly, and an induction probe is arranged on a centering plate of the centering mechanism; the second conveying assembly, the centering mechanism and the inductive probe are electrically connected with the controller.

7. The PCB board direction identification adjustment structure of claim 6, wherein:

the second reversing mechanism is arranged above the second conveying assembly and comprises a second rotating plate, a second rotating driving piece and a second lifting assembly which are sequentially connected, and a vacuum chuck is arranged on the second rotating plate.

8. The PCB board direction identification adjustment structure of claim 7, wherein: and an avoidance port for giving way to the transplanting assembly is formed in the second conveying assembly, and the transplanting assembly is arranged in the avoidance port.

9. A conveyor, includes frame, its characterized in that: the PCB direction recognition and adjustment structure of any one of claims 1-8 is arranged on the frame.

10. The delivery device of claim 9, wherein: the rack is provided with a shield, the PCB direction recognition and adjustment structure is positioned in the shield, and the shield is provided with an observation window and a switch door.