Noise restraint apparatus for digital camera

1. A noise restraint apparatus for a digital camera which has an imaging device for imaging a photographic subject, comprising:

an outputting processor that outputs a vertical synchronous signal to said imaging device; and

a controlling processor that controls an output cycle of said vertical synchronous signal;

said output cycle set to a first cycle, for a first period which is the period before an exposure operation, in which a photographic subject is imaged by said imaging device, a second cycle which is longer than said first cycle, for a second period, while said exposure operation is performed, a third cycle which is shorter than said second cycle, for a third period which is the period where an operation mode of said imaging device is changed from a first mode for said exposure operation to a second mode for reading of data obtained in said exposure operation, after said exposure operation is terminated, and a fourth cycle which is longer than said third cycle, for a fourth period which is the period where said data obtained in said exposure operation is read from said imaging device for every field, after changing to said second mode.

2. The noise restraint apparatus according to claim 1 , further comprising:

an exposure time judging processor that judges whether a time for said exposure operation is longer than a specified time;

said outputting processor outputting said vertical synchronous signal with said second cycle while said exposure operation is performed, in accordance with a control signal output by said controlling processor, when it is judged that said time for said exposure operation is longer than said specified time by said exposure time judging processor.

3. The noise restraint apparatus according to claim 1 ,

wherein said second cycle is equal to the time for reading of data obtained in said exposure operation from said imaging device for one field, after the termination of said exposure operation.

4. The noise restraint apparatus according to claim 1 , wherein said first cycle is 5 ms, and said second cycle is 168.3 ms.

5. A method for restraining noise in a digital camera which has an imaging device for imaging a photographic subject, comprising:

outputting a vertical synchronous signal at a first cycle for a first period which is a period before an exposure operation in which a photographic subject is imaged by said imaging device;

outputting said vertical synchronous signal at a second cycle for a second period which is a period while said exposure operation is performed, wherein said second cycle is longer than said first cycle;

terminating said exposure operation by outputting said vertical synchronous signal after a time for said exposure operation has passed;

outputting said vertical synchronous signal at a third cycle for a third period which is a period during the period where an operation mode of said imaging device is changed from a first mode for said exposure operation to a second mode for reading of data obtained in said exposure operation, after said exposure operation is terminated, wherein said third cycle is shorter than said second cycle; and

outputting said vertical synchronous signal at a fourth cycle for a fourth period which is a period during the period where said data obtained in said exposure operation is read from said imaging device for every field, after changing to said second mode, wherein said fourth cycle is longer than said third cycle.

6. The method for restraining noise according to claim 5 ,

wherein after setting said fourth cycle, said vertical synchronous signal is output with said first cycle.

7. The method for restraining noise according to claim 5 ,

wherein said second cycle and said fourth cycle are the same.

8. The method for restraining noise according to claim 7 ,

wherein said second cycle is equal to the time for reading of data in said exposure operation from said imaging device, for one field.

9. The method for restraining noise according to claim 8 ,

wherein said second cycle and said fourth cycle are 168.3 ms.

10. The method for restraining noise according to claim 5 ,

wherein said first cycle, and said third cycle are the same.

11. The method for restraining noise according to claim 10 ,

wherein said first cycle, and said third cycle are 5 ms.

12. The method for restraining noise according to claim 5 ,

wherein a time for said exposure operation is longer than a specified time.

13. The method for restraining noise according to claim 5 ,

wherein said exposure operation is performed in the bulb exposure mode.