Photography – Camera detail
Reexamination Certificate
1999-02-18
2001-05-08
Perkey, W. B. (Department: 2851)
Photography
Camera detail
Reexamination Certificate
active
06227728
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical apparatus equipped with a microcomputer having an unrewritable memory and a rewritable non-volatile memory.
2. Description of Related Art
Heretofore, cameras equipped with a one-chip microcomputer and arranged to perform a film transport control, an exposure control, a focus adjusting control and the like by using the microcomputer have been proposed. Generally, in such types of cameras, when the power source is turned on, a reset circuit cancels a reset state of the microcomputer so as to start executing a control program installed in the microcomputer.
Also, in recent years, cameras having a microcomputer containing therein a flash ROM (flash read-only memory), which is a rewritable non-volatile memory, have come into practical use. Accordingly, it has become possible to adapt the camera to a newly-developed accessory by modifying a control program after the production of the camera.
However, there is a problem that if, when a program is being written in the flash ROM, the contents of the flash ROM are destroyed due to some accidents, the camera would perform an abnormal operation.
Also, as disclosed in Japanese Laid-Open Patent Application No. Hei 8-320834, a method for preventing malfunction of a program written in the flash ROM has been proposed, in which correct check-sum values for the horizontal and vertical directions are beforehand stored in an EEPROM (electricaly erasable programmable read-only memory), a check-sum value of a program to be executed is calculated before an ordinary operation, and it is verified whether the calculated check-sum value coincides with the check-sum value stored in the EEPROM. However, since, in such a method, a program for calculating a check-sum value is written in the flash ROM, if the check-sum calculating program itself has any defect, not only cannot the check-sum value be calculated, but also malfunction cannot be prevented.
BRIEF SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a camera having a memory in which control programs are stored, the camera comprising a flash memory in which a control program or data for controlling the camera is stored, and a masked ROM in which a program for determining whether the control program or data stored in the flash memory is proper, wherein the program stored in the masked ROM is executed in advance of execution of the control program stored in the flash memory, so that any impropriety in the control program or data stored in the flash memory can be known beforehand.
The above and further aspects and features of the present invention will become apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5053797 (1991-10-01), Samuels et al.
patent: 5132716 (1992-07-01), Samuels et al.
patent: 5481326 (1996-01-01), Yasukawa
patent: 5721983 (1998-02-01), Furutsu
patent: 5828911 (1998-10-01), Miyazawa
patent: 5905921 (1999-05-01), Miyazawa
patent: 8-320834 (1996-12-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Perkey W. B.
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