JP2005128613A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To normally start in turning on a power supply for promoting the rewriting of an operation program again when a power supply is turned off during the rewriting the operation program into a rewritable non-volatile memory without requiring any additional part. <P>SOLUTION: A flash memory has a boot area 21 and an operation program area. In the operation program area, a first operation program area 22 rewritable by a user and a second operation program area 24 prevented from user rewriting are set. The operation program, its check sum value 221, and its data size value 223 are stored at least in the operation program area 22. When the occurrence of an abnormal condition is determined in the operation program 222 inside the first operation program area 22 in updating by checking the check sum value 221 and the data size value 223, an operation program 242 inside the operation program area 24 is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that is program-controlled according to an operation program, and more particularly to an image forming apparatus that stores an operation program in a rewritable nonvolatile memory.

  A flash memory that is a non-volatile rewritable memory is provided as an apparatus that can easily rewrite the operation program of the apparatus. This flash memory includes a rewrite program area (boot area) that describes a rewrite procedure and an operation program area. It is known that the division is set and the operation program can be rewritten according to the rewrite program (see, for example, Patent Document 1).

However, in writing to the flash memory, due to its structure, it is necessary to perform a write operation after erasing information once written. Therefore, when the program memory is used as the flash memory and a new program is rewritten, the program is temporarily erased. At this time, if a power failure occurs or the power is accidentally turned off, even if the power is turned on again, normal operation cannot be performed because the program is erased.
JP 2000-29680 A JP 2002-26449 A

  In relation to the above problem, the first area of the flash memory that stores the operation program has a non-volatile latch that holds a signal indicating the rewrite state of the flash memory. There is a technique for switching whether to rewrite the flash memory by copying the rewrite program in the second area to the SRAM, or to start rewriting the flash memory by copying the rewrite program in the third area of the flash memory to the SRAM. (See Patent Document 2).

  However, this prior art requires a nonvolatile latch circuit that holds the rewritten state of the flash memory, which increases the cost.

  The present invention has been made in view of the above-described conventional problems, and the purpose thereof is normal even when the power is turned off even if the power is turned off during rewriting of the operation program to the rewritable nonvolatile memory. It is an object of the present invention to provide an image forming apparatus that can be started up and re-prompted to rewrite an operation program, and that can improve reliability at low cost without requiring additional components.

  An image forming apparatus according to the present invention is an image forming apparatus that operates in accordance with an operation program, a rewritable nonvolatile memory that stores the operation program and a boot processing program at power-on, and an operation stored in the nonvolatile memory A CPU that controls the apparatus based on a program; and a memory that temporarily stores data when the CPU performs control. The nonvolatile memory includes a boot processing program area and an operation program area. In the operation program area, two areas, a first operation program area that can be rewritten by the user and a second operation program area in which user rewriting is suppressed, are set. The checksum value and data size value are stored with the program. And it features.

  In the present invention, two areas each storing an operation program are set in the nonvolatile memory, and only one of the operation program areas can be rewritten by the user. When the user updates the operation program, the operation program in the user-rewritable operation program area is rewritten. The second operation program area where user rewriting is inhibited does not change at all. Therefore, even if an abnormal situation such as power OFF occurs during the operation program update operation, if the abnormality is detected, the operation program in the second operation program area is used to operate the image forming apparatus. Can be launched. No special additional parts are required for the present invention.

  For detecting an abnormality, the CPU checks the entire second operation program area based on the checksum value and data size stored in the operation program area that can be rewritten by the user when the power is turned on according to the boot processing program. The sum value and the data size are checked, and when the check sum value is different or the program size is different, the operation program in the second operation program area can be activated.

  Preferably, the CPU prompts the user to rewrite the operation program again when it is determined that the user-rewritable operation program area is abnormal.

  The operation programs in the two operation program areas are preferably stored in a compressed format. As a result, the storage capacity of the necessary operation program area can be reduced. The CPU further includes a memory for temporarily storing data used when performing control, and the CPU operates by referring to the operation program expanded on the memory after decompressing the compressed operation program.

  According to the present invention, when the operation program is updated to the user, the operation can be resumed normally without falling into a situation where the operation program of the apparatus cannot be started up even if the power is accidentally turned off during the update. In addition, for that purpose, no special hardware parts are required, so that the reliability of the apparatus can be increased at low cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of an image forming apparatus according to the present invention. In FIG. 1, a CPU 11, a RAM 12, a flash memory 13 (a rewritable nonvolatile memory), an input / output interface (I / F) 14, an LCD (display unit) 15, a KEY (key operation unit) 16, and a printing unit 17 are included. Are connected to each other via a bus 18.

  The CPU 11 is a central processing unit that controls the operation of the entire apparatus. The RAM 12 is a normal volatile memory (for example, SRAM) used as a work area for the CPU 11 and a temporary data storage area. The flash memory 13 is a rewritable nonvolatile memory that stores an operation program for the CPU 11 to control the image forming apparatus and a boot processing program describing a rewrite procedure of the operation program. The input / output interface unit 14 is connected to an external computer terminal device or the like, through which image data is transferred. The LCD 15 is a display unit that performs display for a man-machine interface. KEY 16 is a key operation unit for the user to select various settings of the image forming apparatus. The printing unit 17 includes a recording head for image formation, and is a part that performs a printing operation under the control of the CPU 11.

  FIG. 2 shows an example of a memory map of the flash memory in the present embodiment. In this example, a boot area 131, a user rewritable area 132, a reserve area 133, a user rewrite inhibition area 134, and a reserve area 135 are provided.

  In the boot area 131, a boot processing program that executes initial processing at power-on, a program that describes an operation program rewrite program, and an operation program that is used from the user rewritable area 22 or the user rewrite suppression area 24 are used. And a program for decompressing a compressed operation program on a RAM.

  The user rewritable area 22 stores a checksum value 221 as a kind of the error detection code and a data size 223 of the operation program together with the operation program 222. In this embodiment, the operation program 222 is stored in a compressed format in order to reduce its storage capacity. The data size value 223 is the size of the operation program after compression.

  The user rewrite suppression area 24 stores an operation program 242, a checksum value 241 as an error detection code, and a data size 243 of the operation program. The operation program 242 is an initial operation program before update. In this embodiment, the operation program 242 is also stored in a compressed format. By storing in a compressed format, the required flash memory capacity can be reduced. However, the checksum value 241 and the data size value 243 in the user rewrite inhibition area 24 are not essential elements.

  FIG. 3 is a flowchart showing the processing contents of a boot processing program that is initially executed by the CPU when the image forming apparatus according to the present embodiment is turned on.

  First, the data in the user rewritable area is read to calculate the checksum value and confirm the data size of the operation program (S31). If the calculated checksum value does not match the stored checksum value 221, it is determined that there is some abnormality in the user rewritable area. That is, it is estimated that the operation program 222 is not in a normal state because the update (version upgrade) of the operation program in the user rewritable area performed immediately before has not been completed normally. Therefore, in step S35, the use of the operation program 242 in the user rewrite inhibition area is determined. Even if the data is abnormal, the calculated checksum value may coincide with the regular checksum value. Therefore, if there is no abnormality in the checksum value, the confirmed data size value is set to the data size value 223. Compare with the stored data size value 223. If the data sizes do not match, it is determined that there is some abnormality, and the process proceeds to step S35 to determine the use of the operation program 242 in the user rewrite inhibition area. Further, the user is informed that the update of the operation program has not been normally completed by displaying a message on the LCD 15 or the like, and prompts the user to execute the update operation again.

  In step S36, the operation program is read from the user rewritable area 22 or the user rewritable inhibition area 24 and developed on the RAM 12 while being decompressed. Thereafter, the operation program is started.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made. For example, the checksum value and the data size value are stored in the header part and the footer part of the program area, respectively, but the storage positions are not limited thereto.

1 is a block diagram illustrating a configuration of an image forming apparatus according to the present invention. It is a figure which shows an example of the memory map of the flash memory in embodiment of this invention. 6 is a flowchart showing the processing contents of a boot program that is initially executed by a CPU when the image forming apparatus according to the embodiment of the present invention is turned on.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... CPU, 12 ... RAM, 13 ... Flash memory (rewritable non-volatile memory), 14 ... Input / output interface (I / F), 15 ... LCD (display part), 16 ... KEY (key operation part), 17 ... Printing section

Claims (4)

In an image forming apparatus that operates according to an operation program,
A rewritable nonvolatile memory for storing the operation program and a boot processing program at power-on;
A CPU for controlling the apparatus based on an operation program stored in the nonvolatile memory,
The non-volatile memory has a boot processing program area and an operation program area. The operation program area includes a first operation program area that can be rewritten by a user and a second operation program area in which user rewriting is suppressed. An image forming apparatus, wherein two areas are set, and at least a first operation program area stores an operation program and its checksum value and data size value.   In accordance with the boot processing program, the CPU checks the checksum value and data size of the entire second operation program area based on the checksum value and data size stored in the user program rewritable operation program area when the power is turned on. 2. The image forming apparatus according to claim 1, wherein when the checksum value is different or the program size is different, the operation program in the second operation program area is activated.   2. The image forming apparatus according to claim 1, wherein the CPU prompts the user to rewrite the operation program again when it is determined that the user-rewritable operation program area is abnormal.   The CPU further includes a memory for temporarily storing data used for control, the operation programs in the two operation program areas are stored in a compressed format, and the CPU decompresses the compressed operation program. The image forming apparatus according to claim 1, wherein the image forming apparatus is expanded in the memory, and the CPU operates by referring to an operation program expanded on the memory.

Images