Transmitting digital images to a plurality of selected receivers over a radio frequency link

#The invention is directed to an electronic camera system. More specifically, the invention is directed to an electronic camera system that includes a transmission mechanism for sending image data to selected receiver units.

#Motion video cameras and electronic still cameras have been utilized for several years in applications involving image data transmission. Electronic image data generated from a video camera, for example, can be transmitted by a conventional broadcast television station and received by any television in the broadcast area tuned to the appropriate channel. It is not possible, however, for the transmitter to select which receivers will obtain the image data, as selection is controlled at the receiver. Image data from electronic still cameras has been transmitted via conventional telephone lines to selected receivers through the use of a computer equipped with a modem. The image data must first be downloaded from the electronic still camera to the computer, which then transmits the image data to a second modem equipped computer via the telephone line where it can be viewed or printed. Unfortunately, the requirement for a telephone line to transmit image data does not allow images to be quickly and easily transmitted from remote field locations to receiver units. While systems have been proposed that utilize radio frequency transmission to transmit image data from an electronic camera to an individual base unit, none of these systems have the capability of selectively transmitting image data to a plurality of receiver units.

#In view of the above, it is an object of the invention to provide an electronic camera system that includes a programmable transmission capability for selectively transmitting electronic image data to a plurality of remote receive units.

#The invention will be described in greater detail with reference to certain preferred embodiments thereof and the accompanying drawings, wherein:

#FIG. 1 is a diagram of a camera system in accordance with a first embodiment of the invention;

#FIG. 2 is a perspective side view of a camera module utilized in the camera system illustrated in FIG. 1;

#A diagram of a camera system in accordance with a first embodiment of the invention is illustrated in FIG. 1. The camera system includes a “clip-on” electronic camera module 10 coupled to a pen-based computer 12 that includes a radio frequency (RF) transmitter module 14 including an antenna. The camera module 10 can be of a form described in copending and commonly assigned U.S. patent application Ser. No. 07/988,517 entitled “Electronic Camera with Memory Card Interface to a Computer”, which describes a removable camera module that fits into and interfaces with a standard PCMCIA card interface slot of a pen-based computer, or of a type described in copending and commonly assigned U.S. patent application Ser. No. 07/988,560 entitled “Electronic Camera Incorporating a Computer-Compatible Bus Interface”, which describes a removable camera module that interfaces directly to a standard personal computer compatible bus. The camera module 10 takes still images that can be displayed on an interactive display screen 16 of the pen-based computer 12. The RF transmitter module 14 can either be a clip-on unit, like the camera module 10, or constructed integrally with the pen-based computer 12. The interactive display screen 16 acts as an input device to the pen-based computer 12, where a stylus or “pen” is used to select various icons or “buttons” displayed on the display screen 16 to enter data or commands into the pen-based computer 12. Still images captured by the camera module 10 are transmitted from the pen-based computer 12 to one or more receiver units, labeled A, B and C in FIG. 1, via the RF transmitter module 14. The still images can be displayed, printed, manipulated or stored at the receiver units A-C.

#The camera module 10 is shown in greater detail in FIGS. 2 and 3 as preferably including a slide-out optical veiwfinder 18, a capture switch 20 for initiating an image capture operation, a lens 22, a flip-out flash unit 24 that protects the lens 22 when the camera module 10 is not in use, and a computer bus connector 26 that connects the camera module 10 to either the internal bus of the pen-based computer 12 or to an interface port (such as a PCMCIA slot) of the pen-based computer 12. Mounting clips 27 are provided to aid in securing the camera module 10 to the pen-based computer 12. As shown in FIG. 4, which illustrates a schematic block diagram of the internal components of the camera module 10, scene light passes through the lens 22, an adjustable aperture 28, a shutter mechanism 30 and a filter 32 to an electronic imaging unit 34. The electronic imaging unit 34 includes a charge coupled device (CCD) electronic imaging sensor 36, for example an Eastman Kodak KAF-400, driven by a CCD driver unit 38. The electronic imaging unit 34 is coupled to an image signal processor 40 that processes an analog image signal generated by the electronic imaging sensor 36 into digital image data, and supplies the digital image data to the computer bus connector 26. Specifically, the analog image signal is supplied to a gain stage, a correlated double sampling (CDS) circuit and then an analog-to-digital (A/D) converter which are not specifically illustrated in the diagram. The digitized output signal from the A/D converter is processed via an EPROM lookup table which performs gamma correction and white balancing. The overall operation of the camera module 10 is controlled by a camera control processor 42 that includes either a general purpose microprocessor or discrete circuit elements, which receives inputs from a light measuring unit 44 and the capture switch 20, and controls the operation of the flash 24, the signal processor 40, and a driver unit 46 that controls the operation of the aperture 28 and shutter 30.

#The operation of the camera system is illustrated in greater detail in the flow diagram illustrated in FIG. 5. The user turns on the pen-based computer 12 using a power switch (not shown) to activate a camera application program stored in a memory unit of the pen-based computer 12, and then flips up the flash unit 24 which causes power to be supplied to the camera module 10 by activating a power switch (not shown). The user frames the subject using the optical viewfinder 18 and presses the capture switch 20 to initiate a sequence where the scene light level is read by the camera control processor 42 using the light measuring unit 44, the aperture 28 is adjusted, and the shutter 30 is opened to expose the electronic image sensor 36 to scene light. The camera control processor 42 also controls the firing of the flash unit 24 if the light measurement taken by the light measuring unit 44 indicates insufficient scene illumination. The image captured by the electronic image sensor 36 is processed by the image signal processor 40 and supplied to the pen-based computer 12 via the connector 26, where it is stored in the memory unit of the pen-based computer 12.