An Elmo™ projector is basically a document camera with projection, frequently used descriptive term for all such type of systems, regardless of who developed them. However it is not a proper use of this term, that’s why several manufacturers fear about losing the value of their brand. If the company is not known, the term document camera or document projector should be used in most cases.
The key function of this type of projector is to show documents and other objects that are not made with transparencies. It includes a digital video camera and a projection lens to work appropriately. More than just documents, projectors can also be employed to display 3D objects in many cases, however they will appear in 2D on screen.
The basic idea of the Elmo™ projector is identical to that of the overhead projector, which came into existence in late 50s and was in use through 90s. These types of projectors were used to make content available to large number of viewers in a classroom or meeting room, but the limitation was that, it could display documents on transparent material only. 3D objects would appear as a black shadow.
With a document projector, not just documents and objects, but moving pictures, like movies can also be displayed. This is not at all effective way of displaying such media. The camera of a document projector doesn’t work with big number of frames/second as opposed to standard video cameras. That is why these projectors are usually referred as document cameras, because motion is not significant while displaying documents. Similarly, when looking at 3D objects with document cameras, they should not move, or move slowly.
Document cameras are real-time image capture devices which are used to display an object to wide range of audience. Similar to an opaque projector, a document camera is capable to enlarge and project the images of real, 3D objects. They are, basically, high resolution web cams. They allow a teacher, lecturer or presenter to write on a sheet of paper or to display a 2D or 3D object. All objects can be displayed by a document camera in theory. Generally objects are just positioned under the camera. The camera takes the picture which consecutively produces a live picture with the help of a projector. Various document camera visualizers give very good flexibility for the placement of objects. Larger objects can just be positioned facing the camera and the camera rotates if required, a ceiling mounted document is used for a larger working area.
Usual applications for a document camera consist of:
- Lecture room or classroom use
- Presentations in official meetings, teaching and conferences
- Presentation of proofs and facts in the court
- Several medical applications ( tele-pathology , tele-medicine and x-rays display)
Formerly epidiascopes and overhead projectors were used for this purpose. Using zoom feature, a document camera can expand the small print in books and project a printed page as a usual transparency. The room lighting should be dark for a document camera. Most document cameras are capable of sending video signals to a computer using a USB cable. Document cameras can also be connected to an interactive whiteboard in place of a standard screen. Few document cameras come with an accessory so it can be used with a microscope.
Prototype document camera
Historically, Document cameras were designed to meet a greater requirement to project and present original documents, plans, drawings and objects directly. WolfVision and Elmo introduced first document cameras and were introduced at the Photokina Trade Fair in 1988.
The use of computers, projectors, and popular presentation programs like Microsoft PowerPoint in meeting rooms, became popular with time. However Document cameras keep on offering a suitable and easy way of displaying documents, books or slides in presentations as needed.
The first projectors and prototypes were mainly simple video cameras. In mid 70s these cameras were assembled and given additional lighting to make sure that they can operate in dim light conditions, and also to offer a reliable quality of projected figures. Document cameras are also regularly get benefits from expansion in other sectors. Towards the end of the 1990s progressive scan cameras came into existence. Today several visualizers are capable of minimum 30 frames per second output, which gives high quality images.
Combination of various different technologies gave birth to the latest design and specification of modern document cameras. The quality of the recorded image depends on the primary components like optics, camera and lighting system. The production of different mechanical designs by individual manufacturers then produces the final product. Today HD Document cameras are available with HDMI output, Audio/Video recording and playback, and some document cameras are also taking advantage of WIFI technology to get rid of the requirement of cables.
Document cameras include a variety of refined automated systems that are developed to make your experience easy and simple. For example, when a new object is displayed, permanent autofocus detection adjusts the focus settings automatically, without any user intervention. They include various other important capabilities like automatic exposure, white balance.
A document camera requires an image display device to display the information to the viewers. Modern motherboards include a range of connections to make sure the flexibility of use. Besides, HDMI, DVI or VGA ports for connecting to displays, there are various other interfaces offered to aid connection to a computer or interactive whiteboard. Moreover, an external PC or laptop can be linked with the document camera to facilitate effortless change between a Power Point presentation and a live demonstration. Some projector devices also control external storage devices and are capable to run files instantly from a USB drive, or they can also save pictures that are taken during the presentation on it.
These document cameras provide regular firmware upgrading which allows its users to have the chance to get benefitted from latest available features.
Document camera types
Document cameras have been divided into 3 groups. Smaller lightweight models, larger sturdier and more stable units or desktop models, and the third group are ceiling mounted visualizers.
Portable and desktop models offer the same environment as an overhead projector. The added flexibility like, the variety of objects that can be displayed to an audience are appreciable. Portable devices can be installed in several locations without any prior special installation.
Ceiling mounted visualizer cameras are quite different from desktop models; larger objects can be displayed using them. The system is installed in the ceiling, so technical tools to limit the views of presenter and audience are not there. Ceiling models are mostly used for video conferencing to create a much better experience for all the members.
Document cameras use in education
Nowadays, document cameras are being used widely in many educational institutes. It gives students an enhanced view of the information that lecturer is presenting to the class. Moreover a document camera can also be an amazing classroom management tool. The teacher can use this device as a timer as the students work alone or in groups. A picture schedule to help English Language Learners understand directions can also be put in place. Document cameras can also be connected with projectors, computers, scanners and other devices.