Pulse or digital communications – Repeaters – Testing
Patent
1991-07-24
1994-06-28
Chin, Stephen
Pulse or digital communications
Repeaters
Testing
375 25, 341 30, 341184, 341 64, H03K 700, H03K 900
Patent
active
053253981
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention generally relates to a communication system for transferring data composed of binary parallel bits from a transmitter to a receiver, and specifically relates to a system for transferring an input data value from a peripheral terminal device to a host computer to process the data. More particularly, the present invention relates to a communication system for transferring a coordinate data value derived from a digitizer operative to effect two-dimensional coordinate designation to a host computer through an interface provided in the host computer.
BACKGROUND TECHNOLOGY
A conventional asynchronous data communication system operating in a start-stop synchronization mode initially converts parallel data bits into serial data bits which are then transferred, i.e. transmitted, from a transmitter to a receiver.
This system is described briefly with respect to an example in which a data value is transferred from a digitizer to a host computer. FIG. 10 is an overall perspective view of a communication system including a digitizer and a host computer. The digitizer 1 is comprised of a tablet planar sensor 2 which defines a two-dimensional coordinate plane. A suitable input tool such as a stylus pen 3 is used to designate a given point on a surface of the tablet planar sensor 2 so that the sensor 2 generates an analog detection signal indicative of the designated point. The digitizer 1 further includes a processing circuit unit operative to calculate data representative of a two-dimensional coordinate value of the designated point according to the analog detection signal. The calculated data are fed to the host computer 5 through a signal cable 4. The host computer 5 is provided with a plurality of different type interfaces for connection with peripheral input and output terminal devices. The interfaces are selected according to a form of the signal to be transferred.
FIG. 11 is a waveform of an output signal transmitted from the digitizer. For example, the digitizer generates a coordinate data value in the form of eight parallel data bits. This eight-bit parallel data value is subjected to parallel/serial conversion to produce an eight-bit serial data signal as shown in FIG. 11. For example, eight parallel data bits represented by 10110101 are converted into a corresponding eight-bit serial data signal represented by 1-0-1-1-0-1-0-1. Such mode of bit data transmission is called an asynchronous system of start-stop synchronization mode as noted before. In order to receive a data signal formed according to the asynchronous system of start-stop synchronization mode, the host computer is typically provided with a particular interface based on an RS-232C standard. Therefore, a peripheral terminal device is generally connected to the host computer through a general purpose RS-232C interface.
The RS-232C interface is normally shared by various kinds of peripheral terminal devices adopted to execute data transfer or transaction according to the asynchronous system of start-stop synchronization mode. However, the RS-232C interface can accept a limited number of peripheral terminal devices to be concurrently accessed by the host computer. Therefore, it is desired to provide a different communication mode for effectively executing data transfer or transaction through other interfaces of the host computer than the RS-232C interface.
The typical host computer is provided with a bus mouse interface specifically designed to be connected to a bus mouse device. A brief description is given herewith for the bus mouse for facilitating understanding of the present invention. A bus mouse is generally utilized as a coordinate input terminal device for a computer. However, the bus mouse can treat only a relative displacement value. Further, since the bus mouse has an overall size considerably greater than a stylus pen used as an input tool of the digitizer, the bus mouse cannot carry out character input and menu selection. On the other hand, the digitizer can treat the absolute coordinate value and
REFERENCES:
patent: 3898647 (1975-08-01), Morra et al.
patent: 4739303 (1988-04-01), Kobayashi
Morii Hiroki
Murakami Azuma
Chin Stephen
Kabushikikaisha Wacom
Vo Don N.
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