Power source apparatus and image forming apparatus

1. A power source apparatus for outputting a voltage of positive polarity and a voltage of negative polarity, the power source apparatus comprising:

a transformer;

a switching unit connected to a primary side of the transformer, configured to drive the transformer;

a capacitive element connected to a secondary side of the transformer;

a first constant voltage element connected to the transformer side with respect to the capacity element;

a second constant voltage element connected to an output side of a voltage with respect to the capacity element;

a feedback unit configured to output a feedback signal based on an output voltage output from a secondary side of the transformer to a load and a threshold value; and

a control unit configured to control, so as to control a voltage of the capacitive element, a drive signal for driving the switching unit based on the feedback signal,

wherein, based on the feedback signal, in a case where a voltage output to the load is a voltage of negative polarity, the control unit controls the drive signal so as to prevent a current from flowing into the first constant voltage element and the second constant voltage element, and in a case where a voltage output to the load is a voltage of positive polarity, the control unit controls the drive signal so that a current flows into the second constant voltage element.

2. The power source apparatus according to claim 1 , wherein the feedback unit controls the feedback signal based on an absolute value of the difference between the voltage output and the threshold value.

3. The power source apparatus according to claim 1 ,

wherein the feedback unit includes an error amplification unit configured to acquire an absolute value of the difference by comparing the voltage output with the threshold value, and

wherein a value of the feedback signal output from the feedback unit increases as the absolute value of the difference increases, and the value of the feedback signal decreases as the absolute value of the difference decreases.

4. The power source apparatus according to claim 1 , wherein the voltage of positive polarity and the voltage of negative polarity are output to the same load.

5. The power source apparatus according to claim 1 , further comprising a current detection unit configured to detect current flowing through a load to which the voltage of positive polarity and the voltage of negative polarity are output,

wherein the voltage of positive polarity or the voltage of negative polarity is adjusted so that current flowing through the current detection unit becomes constant.

6. The power source apparatus according to claim 1 ,

wherein, in a case where the voltage of positive polarity is output, a current is prevented from flowing into the second constant voltage element.

7. An image forming apparatus for forming an image on a recording medium, the image forming apparatus comprising:

an image forming unit configured to form an image; and

a power source configured to output a voltage of positive polarity and a voltage of negative polarity to the image forming unit,

wherein the power source includes:

a transformer;

a switching unit connected to a primary side of the transformer, configured to drive the transformer;

a capacitive element connected to a secondary side of the transformer;

a first constant voltage element connected to the transformer side with respect to the capacity element;

a second constant voltage element connected to an output side of a voltage with respect to the capacity element;

a feedback unit configured to output a feedback signal based on an output voltage output from a secondary side of the transformer to a load and a threshold value; and

a control unit configured to control, so as to control a voltage of the capacitive element, a drive signal for driving the switching unit based on the feedback signal,

wherein, based on the feedback signal, in a case where a voltage output to the load is a voltage of negative polarity, the control unit controls the drive signal so as to prevent a current from flowing into the first constant voltage element and the second constant voltage element, and in a case where a voltage output to the load is a voltage of positive polarity, the control unit controls the drive signal so that a current flows into the second constant voltage element.

8. The image forming apparatus according to claim 7 , wherein the feedback unit controls the feedback signal based on an absolute value of the difference between the voltage output and the threshold value.

9. The image forming apparatus according to claim 7 ,

wherein the feedback unit includes an error amplification unit configured to acquire an absolute value of the difference by comparing the voltage output with the threshold value, and

wherein a value of the feedback signal output from the feedback unit increases as the absolute value of the difference increases, and the value of the feedback signal decreases as the absolute value of the difference decreases.

10. The image forming apparatus according to claim 7 , wherein the voltage of positive polarity and the voltage of negative polarity are output to the same load.

11. The image forming apparatus according to claim 7 , further comprising a current detection unit configured to detect current flowing through a load to which the voltage of positive polarity and the voltage of negative polarity are output,

wherein the voltage of positive polarity or the voltage of negative polarity is adjusted so that current flowing through the current detection unit becomes constant.

12. The image forming apparatus according to claim 7 , wherein the image forming unit includes a fixing unit configured to fix the image on the recording medium.

13. The image forming apparatus according to claim 7 , wherein the image forming unit includes a transfer unit configured to transfer the image to the recording medium.

14. The image forming apparatus according to claim 7 ,

wherein, in a case where the voltage of positive polarity is output, a current is prevented from flowing into the second constant voltage element.