RU2635790C2 - Multifunctional interactive training range-room - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: inputs of the multimedia projectors are connected to the outputs of video switcher, to the first and second inputs of which the video signal is submitted from the first outputs of the first and second teacher computers, respectively, from the second outputs of which the USB signal is submitted to two attachments to multimedia projectors. The third input of the signal switch receives the USB signal from the third output of one of the computers from its fourth output which receives the audio signal to the first input of the mixer, the second input of which receives the audio signal from the third output of the other computer. The third and fourth inputs of the mixer receive audio signals from the teachers' microphones. The mixer output is connected via an acoustic amplifier to a distributed speaker system. At the same time, teachers' tablets, trainees' tablet computers, teachers' computers contained in the utility model are united by a local computer network.

EFFECT: extension of the functionality of the interactive training range-room, which is provided with equipment including two reflective screens that are installed horizontally and built into the counter, above which there two multimedia projectors and two attachments to multimedia projectors are placed.

2 cl, 15 dwg

Description

The invention relates to the field of technical training tools and is intended to provide various types of training sessions, both of a traditional type, such as a lecture, seminar, practical lesson, and innovative ones - a business game, a debate, a webinar.

Applied hardware and software solutions allow you to implement the functions of the training ground and the situational center, to carry out simulation modeling of various introductory and problem situations, learn the rules of the road, conduct operational and tactical exercises, and develop teamwork skills.

A well-known real-time training system (RU 106016), which contains workstations with trainee computers and means for displaying information for trainees in group perception mode, trainee computers are connected via the Internet or WI-FI to a server with a training software product and communication, the server is connected by direct and feedback with a user database containing media content, while the computers of the students have two displays, and the system via the Internet or WI-FI connection the teacher’s computer is turned on with the server, and the means for displaying information for students in group perception mode are connected to the teacher’s computer, and the server is also connected to the school administrator’s computer via the Internet or WI-FI. Moreover, the server via the Internet can be connected to remote computers of the trainees, and the means for displaying information for trainees in the group perception mode can be: a projector, an electronic board, a printer, a scanner.

Known interactive study room on labor protection (RU 106017), containing a teacher’s computer with an operating system and software and having means of connecting to network equipment, to an interactive whiteboard, to which at least one teacher’s tablet, a multimedia projector and a device for reading and (or) reproducing sheet documents, a video camera, means for connecting laboratory equipment. The cabinet contains a server with software for individual or group training, testing of acquired knowledge and exams and storage of information: a multimedia library on labor protection, test and exam results, performance analysis on the topics studied, for each student, while the server is connected via a local area network to individual computers of students, the teacher, with video conferencing, the Internet and is connected to an uninterruptible power supply; a Maxim or Gosha simulator is installed on the table, connected to the server, and the sound speaker system is connected to the teacher’s computer, and the office contains visual training material: mannequins in protective suits, posters and stands for labor protection.

An interactive study room (RU 68162) was chosen as a prototype, the use of which will expand the arsenal of teaching aids and also increase the effectiveness of the learning process. Interactive study room includes: teacher's computer; interactive whiteboard connected to the teacher's computer; a multimedia projector connected to the teacher’s computer and designed to project multimedia data onto an interactive whiteboard; at least one teacher tablet, each of these teacher tablets being connected to an interactive whiteboard; a group of student test panels connected each to an interactive whiteboard; at the same time, the operating system and at least the software for operating the interactive whiteboard in interaction with the teacher’s tablet and the student’s test panels are stored in the teacher’s computer memory. If necessary, this office can be supplemented with a multifunctional device for scanning and (or) printing, a camera for receiving photo and (or) video recordings, means for connecting to network equipment and means for connecting to laboratory equipment.

However, the above devices have the following disadvantages. The interactive whiteboard used in these devices has limited perception capabilities, which are determined by its small geometric size (usually not more than 1.5 by 2.5 meters). Thus, the trainees are at different distances from the blackboard, which affects the assimilation of educational material (the effect of "back desk"). In addition, the interactive whiteboard allows simultaneous use of the interactive feedback of two to three trainees, while the remaining members of the study group are passive observers.

Multimedia projectors, which are an integral part of the above devices, are usually located under the ceiling in front of the board, i.e. are in the zone of attention of the trainees, thereby creating a distraction.

In the known devices there is also no possibility to simultaneously solve various educational tasks or one task, but in different ways.

The task to which the invention is directed is to expand the functionality of the training room training ground.

The problem is solved using a device that includes the first teacher’s computer, the first multimedia projector, the first teacher’s tablet, and the second teacher’s computer, the second multimedia projector, the first and second reflective screens, the first and second interactive set-top boxes for the first and second multimedia projectors, a switch video signals, the teacher’s second tablet, trainee’s tablet computers, mixer, speaker amplifier, distributed speaker system. In this case, the first and second reflective screens are installed horizontally and built into the countertop, made with the possibility of placing on it along with tablet computers trainees, as well as notebooks, printed documents. In this case, the first output (video) of the first computer of the teacher is connected to the first input (video) of the video switch. The second output (video) of the second teacher’s computer is connected to the second input (video) of the video switch. The second output (USB) of the first teacher’s computer is connected to the third input (USB) of the signal switch. The first output (video) of the signal switch is connected to the input of the first multimedia projector, the second output (video) of the signal switch is connected to the input of the second multimedia projector. The third output (USB) of the first computer of the teacher is connected to the input of the first console of the first multimedia projector. The second output (USB) of the second computer of the teacher is connected to the input of the second console of the second multimedia projector. The fourth output of the teacher’s first computer (audio) is connected to the first input of the mixer, the second input of which is connected to the third output (audio) of the second teacher’s computer, and the teachers ’microphones are connected to the third and fourth inputs of the mixer and the mixer output is connected to the distributed speaker system through an acoustic amplifier. At the same time, teachers' computers, teachers' tablets, students' tablet computers are connected by a local area network (LAN).

One of the features of the present invention is that the brackets with multimedia projectors, together with interactive consoles to them, are mounted above the reflective screens so that the optical axis of the lenses are offset from the surface of the reflective screens and are away from their working space. Preservation of the necessary image proportions is achieved by means of keystone correction built into multimedia projectors. This arrangement has several advantages. In addition to the obvious aesthetic effect, the removal of bulky devices from the space above the surface of the table into which reflective screens are built-in, this made it possible to organize uniform enough bright lighting on the table surface, which in turn facilitated the work of students with documents, including handwritten and damaged ones, and also small-scale maps and diagrams.

In FIG. 1, 2, 3 shows a device where:

1 - the first reflective screen;

2 - the second reflective screen;

3 - countertop;

4 - students' tablet computers;

5 - the first computer of the teacher;

6 - the second computer teacher;

7 - video switch;

8 is a first multimedia projector;

9 - a second multimedia projector;

10 - interactive set-top box for the first multimedia projector 8;

11 is an interactive set-top box for the second multimedia projector 9;

12 - mixer;

13 - acoustic amplifier;

14 - distribution speaker system.

15 - tablets of teachers;

16 - microphones of teachers.

In this case, the first and second reflective screens 1, 2 are installed horizontally and built into the countertop 3, made with the possibility of arranging on it along with the tablet computers of the student 4 also notebooks, printed documents. The first output (video) of the first computer of teacher 5 is connected to the first input (video) of the video switch 7, the second input (video) of which is connected to the first output (video) of the second computer of teacher 6. The second output (CSS) of the first computer of teacher 5 is connected to the third the input (USB) of the video switch 7. The first output (video) of the video switch 7 is connected to the input of the first multimedia projector 8. The second output (video) of the video switch 7 is connected to the input of the first multimedia projector 9. The third the output (USB) of the first computer of the teacher 5 is connected to the input (USB) of the interactive set-top box to the first multimedia projector 10. The second output (USB) of the second computer of the teacher 6 is connected to the input (USB) of the interactive set-top box to the second multimedia projector 11. The fourth output (audio) the first teacher’s computer 5 is connected to the first input of the mixer 12, the third (audio) output of the second teacher’s computer 6 is connected to the second input of the mixer 12, the output of which is connected through the acoustic amplifier 13 to the distributed acoustics system 14. At the same time, tablet computers of students 4, computers of teachers 5, 6, tablets of teachers 15 are interconnected by a local area network (LAN). And the third and fourth inputs of the mixer 12 are connected to the microphones of teachers 16.

In FIG. 4 shows the location of the multimedia projectors 8, 9 together with their interactive consoles 10, 11 with respect to the wide-format interactive horizontal information field (hereinafter - the field), which is two reflective screens 1, 2, where the brackets with multimedia projectors 8, 9 together with the interactive consoles to them 10, 11 are fixed in such a way that the optical axis of the projection lenses are offset relative to the field surface and are located away from the working space of the field.

The present invention is a two-channel device, where the first teacher’s computer 5, multimedia projector 8 with interactive set-top box 10, reflective screen 1, sound amplification equipment: mixer 12, acoustic amplifier 13, distribution speaker system 14 comprise one channel, for example, A, and the second computer teacher 6 multimedia projector 9 with an interactive set-top box 11, a reflective screen 2 and a mixer 12, an acoustic amplifier 13, a distribution speaker system 14 are another a channel, for example, B. Each of the channels is able to maintain and control the information flow in the form of a training task stored in the memory of the teacher’s computer 5 or 6, projected using a multimedia projector 8 or 9 onto the corresponding reflective surface 1 or 2, the interactivity of which is provided by the influence of IR -radiation from the corresponding interactive set-top box 10 or 11. Interaction between the channels is provided by means of auxiliary devices: a controlled video signal switch 7 and a locale nnoy computer network (hereinafter referred to as the LAN). Interaction with the LAN is carried out through network adapters that are part of the computers of teachers 5 and 6. The LAN itself belongs to the basic equipment of the educational institution and is not included in the utility model.

The use of two multimedia projectors of channels A and B is primarily due to the need to obtain, without distortion, a large illuminated surface sufficient to accommodate at least thirty student workstations (average size of the study group). In addition, this provides the possibility of obtaining various combinations of the projected image, which may vary depending on the educational tasks (see Fig. 5). A variety of combinations is also supported by the settings of the video card modes of teachers' computers 5, 6 ("two monitors", "clone", etc.), as well as the adjustments of the optical systems of projectors 8, 9.

The main combinations:

1. - the image of channel A is duplicated on screens 1 and 2;

2. - the image of channel A is mirror-duplicated on screens 1 and 2;

3. - the image of channel A is stretched to screens 1 and 2;

4. - the image of channel A is mirrored on screens 1 and 2;

5. - the image of channel A goes to screen 1, the image of channel B goes to screen 2;

6. - the image of channel A goes to screen 1, the image of channel B flips to screen 2;

7. - the image of channel B is stretched to screens 1 and 2;

8. - the image of channel B is mirrored on screens 1 and 2.

Thanks to the use of two interactive prefixes 10, 11, designed to implement the “feedback” effect with reflective screens, it was possible to obtain an interactive surface along the entire length of the table, which allowed all members of the study group to actively participate in solving the learning tasks posed by teachers related to movement by touch finger or pointer directly trained cars at intersections in driving lessons, forces and means on topographic maps and so on. A similar effect is usually obtained through the use of interactive whiteboards, which are very expensive and small in size, preventing more than 2-3 students from working with them simultaneously. While applying the proposed utility model, the number of actively participating students can increase to 30 people (the whole group).

The presence of two teacher jobs equipped with computers 5, 6, provides additional opportunities in the application of the utility model. For example, you can conduct a lesson in the form of a brain ring and so on. In this case, the group is divided into two subgroups, each of which may have its own leader.

The presence on the perimeter of the reflective screens of the usual countertop 3 provides the convenience of working with both printed documents and tablet computers 4 students.

The cabinet equipment includes equipment for providing access to electronic information resources over the air via Wi-Fi.

This further expands the functionality of the cabinet. If students use tablet computers 4, they will also be able to work with their individual files on the main information field 1, 2.

Both computers of teachers 5, 6 are equipped with uninterruptible power supplies, have a LAN connection with local electronic information resources and the Internet.

The equipment of the cabinet allows you to fully view multimedia files. To ensure the reproduction of the acoustic component of multimedia, the sound card outputs of teachers' computers 5, 6 through a mixer 12 and an acoustic amplifier 13 are connected to a distributed speaker system 14, which includes sound speakers located around the perimeter of the room. Through the microphones of teachers 16, it is possible to amplify speech, as well as make audio recordings for creating archives of multimedia educational materials.

Also, when using the invention, it remains possible to implement the traditional teaching method using notebooks and printed documents (books, workshops, study guides), since this possibility is provided by the presence of around the perimeter of the reflective screens of the countertop 3 with a width of ~ 40 cm.

The work of a multifunctional interactive classroom-training ground in the implementation of the functions of the training ground and a situational center with simulation modeling of problem situations occurs as follows:

- in the computer memory of the teacher’s workplace 5 or 6, data about the educational task are entered via the keyboard or from the local computer network, and is also imported from any available medium

- from the output of the video card of computers 5, 6 (1 output), a video signal containing information about the training task is fed to the video signal switch 7, from where it is fed to multimedia projectors 8, 9;

- the image from the multimedia projectors 8, 9 is projected onto the reflective screens 1, 2;

- at the same time, the control signal from the USB 2 output of the teacher’s computer 5 is fed to the control input of the video signal switch 7 and determines its operation mode (single-channel or two-channel), and also indicates which reflective screen 1 or 2 and in which combinations to project the training task (one or two)

- at the same time, the control signal from the USB 3 output of the teacher’s computer 5 is fed to the interactive set-top box to the multimedia projector 10 and the control signal from the USB 2 output of the teacher’s computer 6 is fed to the interactive set-top box to the multimedia projector 11, which form an interactive field by generating calibrated infrared pulses on the surfaces of reflective screens 1 and 2;

When this field crosses a foreign object (hand or pointer), a command is sent to the computer to move the corresponding image element.

Acoustic signals accompanying the training task come from the audio outputs of the computers of teachers 5 and 6 to inputs 1 and 2 of mixer 12. After amplification and normalization, both of these signals or one of them, depending on the settings of mixer 12, are fed to the input of acoustic amplifier 13, where they are amplified to necessary for loud reproduction, and then fed to the speakers of the distributed speaker system 14. The signal from the microphones of the teachers 16 is fed to the inputs 3 and 4 of the mixer 12, whereby speech is amplified, and also for making audio recordings for creating archives of multimedia educational materials.

If it is necessary for students to use tablet computers 4, the control signal from the additional USB output of the teacher’s computer is sent to a Wi-Fi router and allows radio access to the training resources of the LAN.

When using trainees' individual tablet computers, 4 training tasks are delivered to them via a radio channel in the WI-FI standard through a router directly from the teacher’s computer 5 or 6. Thus, for example, individual testing or solving a training problem is carried out. At the end, the data can be presented at the request of the teacher on reflective screens 1, 2 for general discussion.

To confirm the implementation of the invention, an electrical circuit was created in which the following standard serial elements were used:

- multimedia projector Optoma XE610ST;

- computer teacher IRU City 319, Intel Core i3 4160, 4 GB DDR3, 500 GB, DVD-RW with a video card SAPPHIRE Radeon HD 5450, 11166-32-10G, 1 GB, DDR3;

- Inter-M distributed speaker system, consisting of six 10-watt speakers;

- trainees' tablet computers (any on the Android or Windows platform, equipped with the WI-FI support function);

- interactive console for the projector Eiki IK-1,

- video switch Kramer VS-42H

- mixer and acoustic amplifier Inter-M RA-2000.

In the center of the office was a horizontally widescreen 2.0 by 6.0 meters interactive information field, which was two reflective screens of channel A and channel B (1 and 2) built into the countertop 3 of a rectangular table elongated along the longitudinal axis of the room. Students were placed at equal distances directly around the interactive information field 1, 2, thereby providing better perception opportunities. At the same time, each of the students had the opportunity to actively use the interactive function, which allowed in practice to realize group or team training.

Taking advantage of the horizontal position of reflective screens in combination with switching equipment, such as a video switch 7, controlled via the USB bus, it was possible to use various combinations of channel image orientation to improve perception, depending on the type of image (text, layout, location map, traffic situation) .

The brackets with multimedia projectors 8, 9 and with interactive prefixes 10, 11 were fixed in such a way that the optical axes of the lenses of the multimedia projectors were offset relative to the surface of the screens 1, 2 and were away from the working space of the table, behind the backs of students, which improved the perception of trainees by excluding auxiliary technical devices from the perception zone.

The cabinet-polygon included acoustic equipment for playing sound files (mixer 12, acoustic amplifier 13, speakers of a distributed speaker system 14).

The use of the present invention made it possible to simultaneously solve various educational problems or one task, but in different ways, due to the presence of two independent channels for supplying information A and B, for example, when working out the tasks of counteracting a conditional opponent, when the training group was divided into two subgroups and one side "Red", and the other for the "blue". In this case, each subgroup was assigned its own introductory, which the trainees practiced. In another option, when each subgroup was assigned the same training task, for example, to analyze the tactical situation on the ground and to develop methods for its optimization, after the task was completed by both subgroups, they were compared among themselves, and then, in the process of joint discussion, the winner was determined.

When studying the rules of the road, images of intersections, sections of roads, both real and imaginary, traffic lights, obstacles, and so on, were projected onto the reflective screens 1, 2 by multimedia projectors 8, 9. Interactive consoles for multimedia projectors 10, 11 formed an interactive field by generating calibrated infrared pulses on the surfaces of reflective screens 1 and 2. Various traffic situations involving vehicles were simulated, the images of which students can move by touching the screen with a finger or a pointer.

During the tactical exercises, maps of the area, forest, mountains, city blocks, both real and imaginary, were projected on the screens. Various situations were simulated, such as an attack by terrorists, search operations, military operations, hostage taking, accidents, catastrophes and so on. The students manipulated the symbols of forces and means, military equipment, the movement of units and units that were moved by touching the screen with a hand or a pointer.

When developing teamwork skills to complicate the tasks to be solved, intensify healthy rivalry and develop tactical thinking, the group was divided into two parts, one of which “played” for the terrorists, and the other for law enforcement officers. At the same time, different data were entered into the memory of computers of workplaces of teachers 5 or 6, depending on who they are intended for.

A similar scheme was implemented in the organization of business games, competitions such as “brain ring”. Moreover, all the information during the lesson was recorded in the memory of teachers' computers 5 or 6, forming over time the training database.

Examples of using a utility model to ensure the educational process.

Example 1. Academic discipline: History of the Fatherland.

Subject: Battle of Kulikovo.

Option 1. One channel is involved. The battle pattern is projected onto the entire surface of the table. The teacher talks about the course of the battle, demonstrating the movement of troops through interactive elements, then answers questions (see Fig. 6).

Disadvantages:

- predominantly passive role of listeners

- listeners 1-3 and 22-24 are far from the center of the image

- Listeners 10-15 and 25-30 see the image upside down.

Option 2. Two channels are involved. The battle pattern is duplicated on

both screens. The teacher talks about the course of the battle, demonstrating the movement of troops through interactive elements, then answers questions (see Fig. 7).

Disadvantages:

- predominantly passive role of listeners

- Listeners 10-15 and 25-30 see the image upside down.

Option 3. Two channels are involved. The battle plan is duplicated on both screens, while the images are deployed symmetrically around the central axis. The teacher talks about the course of the battle, demonstrating the movement of troops through interactive elements, then answers questions (see Fig. 8).

Disadvantages:

- predominantly passive role of listeners.

Option 4. Two channels are involved. The first stage of the battle is projected onto one screen, the second stage of the battle is projected onto another screen, while the images are rotated symmetrically around the central axis. The teacher talks about the course of the battle, demonstrating the movement of troops through interactive elements, then answers questions (see Fig. 9).

Disadvantages:

- predominantly passive role of listeners.

Option 5. Two channels are involved. The position of the Russian troops is projected on one screen, and the position of the Mongol-Tatars on the other. The teacher tells the initial arrangement of units, then offers students 1-15 to fight on the side of the Mongol-Tatars, and students 16-30 lead the battle for the Russians, accompanying their actions with comments and analysis of the situation. Listeners fight by moving interactive elements indicating military units on the screen surface. Thus, various options for the development of hostilities are lost. Opponents can change places. Each student is actively involved in the process of mastering the material. Moreover, the above-mentioned disadvantages are eliminated, contributing to the achievement of the maximum pedagogical effect (see. Fig. 10).

Example 2. Academic discipline: Rules of the road.

Topic: U-turn in various traffic situations.

Option 1. One channel is involved. The image is arranged in such a way that in front of each group of listeners different traffic situations are shown. The teacher offers students various maneuver options and comments on them (see Fig. 11).

Option 2. Two channels are involved. The first traffic situation is projected onto one screen, the second situation is projected onto another screen, while the images are rotated symmetrically around the central axis (see Fig. 12).

Option 3. One channel is involved. The group is divided into six subgroups. Each subgroup has its own image of the traffic situation. After setting the task, students disassemble their tasks and offer solutions. They demonstrate their results by moving interactive elements representing vehicles on the screen surface (see Fig. 13).

Option 4. Two channels are involved. The group is divided into two subgroups: 1-15 and 16-30. Each group controls its own vehicle, which move towards each other and at the same time make a U-turn maneuver (see Fig. 14). Traffic situations, obstacles, street shape are set by the teacher and change easily.

Example 3. Training discipline: Rules of the road.

Subject: Drive through complex road junctions.

Two channels are involved. The group is divided into two subgroups: 1-15 and 16-30. Each subgroup controls one or more vehicles, moving interactive elements on the surfaces of the screens. The teacher sets the task of finding the optimal path from one junction to another, followed by a change in direction. It is possible to use a competitive technique using virtual timers (see Fig. 15).

Example 4. The discipline and topic of the lesson can be any.

Form of study: a business game in the style of "Brain Ring". Two channels are involved, as well as individual tablet computers of the trainees (at least one per subgroup). The group is divided into two subgroups: 1-15 and 16-30. Groups ask one another questions prepared in advance. Questions come from tablet computers 4 via the wi-fi radio channel to teachers' computers 15, from where they are transmitted to reflective screens 1, 2, each subgroup’s screen is different, then a general list of questions and answers is formed. For a limited time, students are encouraged to answer the largest possible number of questions of the "enemy". At the same time, points are awarded for correct answers, and penalty points for incorrect answers. The winner is the subgroup with the most points.

Example 5. The discipline and topic of the lesson can be any.

Form of the lesson: “classic” seminar.

Presentation equipment is not involved. Trainees work with notebooks, summaries, prints. At the same time, the surface of the reflective screens 1, 2 becomes the surface of the desktop on which it is convenient to place visual aids, posters, mock-ups and so on.

This is only a small part of the many examples that can be implemented to ensure the educational process through the proposed utility model. At the same time, students receive all the necessary knowledge and skills necessary for the rapid assimilation of educational material, due to the ease of changing images, the amount of learned information is increased, and the visibility achieved contributes to a deep study of the subject.

Teachers can work alone or together. At the same time, they can either be at their workplaces or arbitrarily move around the classroom, using a personal tablet computer to control the presentation. This ensures the multifunctionality and flexibility of the educational process, combines an integrated and differentiated approach to learning, which clearly demonstrates the novelty of the proposed utility model.

Claims (2)

1. A multifunctional interactive study room, including the first teacher’s computer, the first multimedia projector, the first teacher’s tablet, characterized in that the device further comprises a teacher’s second computer, a second multimedia projector, first and second reflective screens, first and second interactive set-top boxes and a second multimedia projectors, a video switch, a second teacher’s tablet, trainee’s tablet computers, a mixer, an acoustic amplifier, a distributed acoustic system, with the first and second reflective screens installed horizontally and built into the countertop, made with the possibility of placing on it, along with tablet computers, students, as well as notebooks, printed documents, and the first output (video) of the first teacher’s computer is connected to the first input ( video) of the video signal switch, the first output (video) of the second teacher’s computer is connected to the second input (video) of the video signal switch, the second output (USB) of the first computer and the teacher is connected to the third input (USB) of the video switch, the first output (video) of the video switch is connected to the input of the first multimedia projector, the second output (video) of the video switch is connected to the input of the second multimedia projector, and the third output (USB) of the first teacher’s computer is connected to the input of the interactive set-top box to the first multimedia projector, the second output (USB) of the second teacher’s computer is connected to the input of the interactive set-top box to the second multimedia projector , the fourth output (audio) of the first teacher’s computer is connected to the first input of the mixer, the third output (audio) of the second teacher’s computer is connected to the second input of the mixer, and the teachers ’microphones are connected to the third and fourth inputs of the mixer and the mixer output is connected to the distributed speaker system At the same time, teachers' computers, teachers' tablets, students' tablet computers are connected by a local area network (LAN). 2. The multifunctional interactive training room-polygon according to claim 1, characterized in that the multimedia projectors together with their interactive set-top boxes are mounted above the reflective screens so that the optical axes of the lenses of the multimedia projectors are offset from the surface of the reflective screens and are away from their working space.

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