Method and apparatus for detecting abnormal characteristic values capable of suppressing detection of normal characteristic values

1. A method for detecting abnormal characteristic values of a plurality of products sequentially manufactured in a same manufacturing line, comprising:

sequentially manufacturing said products;

determining whether or not a monotonic successive-decrease tendency has occurred in a plurality of sequentially-obtained characteristic values of said products;

determining whether or not at least a last one of said characteristic values is located within a control region narrower than an allowable region and outside a normal region narrower than said control region; and

detecting an alarm state when said successive-decrease tendency has occurred and said last characteristic value is located within said control region outside said normal region and adjusting said sequential manufacturing in accord with said detected alarm state when said alarm state is detected.

2. The method as set forth in claim 1 , further comprising generating an alarm signal when said alarm state is detected.

3. The method as set forth in claim 1 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is above said control center value and below an upper limit of said control region.

4. The method as set forth in claim 3 , wherein a difference between the lower limit of said normal region and said control center value is different from a difference between said control center value and the upper limit of said normal region.

5. The method as set forth in claim 1 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is the same as said control center value.

6. A method for detecting abnormal characteristic values of a plurality of products sequentially manufactured in a same manufacturing line, comprising:

sequential manufacturing said products;

determining whether or not a monotonic successive-increase tendency has occurred in a plurality of sequentially-obtained characteristic values of said products;

determining whether or not at least a last one of said characteristic values is located within a control region narrower than an allowable region and outside a normal region narrower than said control region; and

detecting an alarm state when said successive-increase tendency has occurred and said last characteristic value is located within said control region outside said normal region and adjusting said sequential manufacturing in accord with said detected alarm state when said alarm state is detected.

7. The method as set forth in claim 6 , further comprising generating an alarm signal when said alarm state is detected.

8. The method as set forth in claim 6 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is above said control center value and below an upper limit of said control region.

9. The method as set forth in claim 8 , wherein a difference between the lower limit of said normal region and said control center value is different from a difference between said control center value and the upper limit of said normal region.

10. The method as set forth in claim 6 , wherein a lower limit of said normal region is the same as said control center value, and wherein an upper limit of said normal region is above said control center value and lower than an upper limit of said control region.

11. An apparatus for detecting abnormal characteristic values of a plurality of products sequentially manufactured in a same manufacturing line, comprising:

a memory section storing a plurality of sequentially-obtained characteristic values of said products;

a successive-decrease tendency determining section, executed by a processor, for determining whether or not a monotonic successive-decrease tendency has occurred in said plurality of sequentially-obtained characteristic values of said products; and

a normal region determining section, executed by said processor, for determining whether or not at least a last one of said characteristic values is located within a control region narrower than an allowable region and outside a normal region narrower than said control region,

thus detecting an alarm state when said successive-decrease tendency has occurred and said last characteristic value is located within said control region outside said normal region.

12. The apparatus as set forth in claim 11 , further comprising an alarm generating section for generating an alarm signal when said alarm state is detected.

13. The apparatus as set forth in claim 11 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is above said control center value and below an upper limit of said control region.

14. The apparatus as set forth in claim 13 , wherein a difference between the lower limit of said normal region and said control center value is different from a difference between said control center value and the upper limit of said normal region.

15. The apparatus as set forth in claim 11 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is the same as said control center value.

16. An apparatus for detecting abnormal characteristic values of a plurality of products sequentially manufactured in a same manufacturing line, comprising:

a memory section storing a plurality of sequentially-obtained characteristic values of said products;

a successive-increase tendency determining section, executed by a processor, for determining whether or not a monotonic successive-increase tendency has occurred in said plurality of sequentially-obtained characteristic values of said products; and

a normal region determining section, executed by said processor, for determining whether or not at least a last one of said characteristic values is located within a control region narrower than an allowable region and outside a normal region narrower than said control region,

thus detecting an alarm state when said successive-increase tendency has occurred and said last characteristic value is located within said control region outside said normal region.

17. The apparatus as set forth in claim 16 , further comprising an alarm generating section for generating an alarm signal when said alarm state is detected.

18. The apparatus as set forth in claim 16 , wherein a lower limit of said normal region is above a lower limit of said control region and below a control center value, and wherein an upper limit of said normal region is above said control center value and below an upper limit of said control region.

19. The apparatus as set forth in claim 18 , wherein a difference between the lower limit of said normal region and said control center value is different from a difference between said control center value and the upper limit of said normal region.

20. The apparatus as set forth in claim 16 , wherein a lower limit of said normal region is the same as said control center value, and wherein an upper limit of said normal region is above said control center value and lower an upper limit of said control region.