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2.发明公开
公开(公告)号：EP0279558A1
公开(公告)日：1988-08-24
申请号：EP88300902.9
申请日：1988-02-03
IPC分类号： G09B5/14
CPC分类号： G09B5/14
摘要： The system comprises a working station (10) for each student and a station (11) for the teachers all stations being connected to a local area data transmission network. Each station is provided with a keyboard (13) and a video display (14). The teacher station controls a teaching monitor procedure by means of which the image displayed on a student video display can be transmitted to his own video display, or an image from his own video display can be transmitted to that of one or more students. The teacher may also control the storage of an image displayed on the video display in a mass memory (17) and recall a selected image therefrom.
The teacher station controls an electronic blackboard procedure enabling selection of the video display of a given working station to function has a blackboard. The blackboard can be operated from the keyboard of any working station enabled by the teacher. The student working stations may be enabled individually or collectively as receivers for the blackboard images. Such images and transmitted and updated continuously by means of a control unit which samples the image at a predetermined frequency and only transmits changing information after each sample. The information is compressed before transmission to reduce the number of signals to be transmitted on the network, and decompressed by the control unit of the receiver when received.摘要翻译： 该系统包括用于每个学生的工作站（10）和用于教师的所有站的站（11），其连接到局域数据传输网络。 每个站设置有键盘（13）和视频显示器（14）。 教师站控制教学监视程序，通过该程序将学生视频显示器上显示的图像发送到他自己的视频显示器，或者可以将他自己的视频显示器的图像发送到一个或多个学生的图像。 教师还可以控制在大容量存储器（17）中显示在视频显示器上的图像的存储并从其中调用所选择的图像。 教师站控制电子黑板程序，使得能够选择给定工作站的视频显示功能具有黑板。 黑板可以由老师启用的任何工作台的键盘操作。 学生工作站可以单独启用或统称为黑板图像的接收器。 这样的图像通过以预定频率对图像进行采样并且仅在每个样本之后发送改变信息的控制单元连续地发送和更新。 信息在传输之前被压缩以减少在网络上要发送的信号的数量，并且在接收时由接收机的控制单元进行解压缩。
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