Image forming apparatus

1. An image forming apparatus, comprising:

a main housing;

an upper housing;

a connecting housing to connect the main housing and the upper housing;

an inner paper discharging space provided between the upper housing and the main housing;

a post-processing unit that is provided at an upper portion of the inner paper discharging space;

a recording medium discharging outlet discharging recording media from the connecting housing, said recording medium discharging outlet positioned downward from the post-processing unit; and

a recording medium discharging tray that is provided at a lower portion of the inner paper discharging space and to which recording medium having image thereon which is not undergone post-processing is discharged via the recording medium discharging outlet,

wherein the post-processing unit comprises:

a main unit; and

a processing tray that is supported pivotably in a vertical direction with respect to the main unit about an axis defined by a side of the processing tray,

wherein the processing tray comprises:

a lock member that is supported movably between a first position and a second position, the lock member being engagable with an engaging hole provided in the main unit at the first position while projecting from an end surface of the processing tray and disengagable from the engaging hole at the second position while being accommodated in the processing tray;

an urging member urging the lock member towards the first position; and

a lock releasing member resisting an urging force applied by the urging member so as to allow the lock member to travel to the second position,

wherein a recording medium depressing member that depresses the recording medium having passed through the recording medium discharging outlet is disposed within a pivotal range of the lock member, and

wherein a first slope is provided on at least one of a contact portion of the lock member and a contact portion of the recording medium depressing member, both of which contact each other when the processing tray pivots downward.

2. The image forming apparatus according to claim 1 , wherein a vertical dimension is greater than a horizontal dimension with respect to a cross sectional view of the first slope.

3. The image forming apparatus according to claim 2 , wherein a second slope is provided on a portion of the lock member on which the recording medium depressing member abuts when the processing tray pivots upward.

4. The image forming apparatus according to claim 1 , wherein a second slope is provided on a portion of the lock member on which the recording medium depressing member abuts when the processing tray pivots upward.

5. A post-processing unit for an image forming apparatus, the image forming apparatus comprising:

a main housing;

an upper housing;

a connecting housing to connect the main housing and the upper housing; and

an inner paper discharging space provided between the upper housing and the main housing;

a recording medium discharging outlet discharging recording media from the connecting housing, said recording medium discharging outlet positioned downward from the post-processing unit, and

a recording medium discharging tray that is provided at a lower portion of the inner paper discharging space and to which recording medium having image thereon which is not undergone post-processing is discharged via the recording medium discharging outlet,

wherein the post-processing unit is provided at an upper portion of the inner paper discharging space comprising:

a main unit; and

a processing tray that is supported pivotably in a vertical direction with respect to the main unit about an axis defined by a side of the processing tray;

wherein the processing tray comprises:

a lock member that is supported movably between a first position and a second position, the lock member being engagable with an engaging hole provided in the main unit at the first position while projecting from an end surface of the processing tray and disengagable from the engaging hole at the second position while being accommodated in the processing tray;

an urging member urging the lock member towards the first position; and

a lock releasing member resisting an urging force applied by the urging member so as to allow the lock member to travel to the second position,

wherein a recording medium depressing member that depresses the recording medium having passed through the recording medium discharging outlet is disposed within a pivotal range of the lock member, and

wherein a first slope is provided on at least one of a contact portion of the lock member and a contact portion of the recording medium depressing member, both of which contact each other when the processing tray pivots downward.

6. The post-processing unit for an image forming apparatus according to claim 5 , wherein a vertical dimension is greater than a horizontal dimension with respect to a cross sectional view of the first slope.

7. The post-processing unit for an image forming apparatus according to claim 6 , wherein a second slope is provided on a portion of the lock member on which the recording medium depressing member abuts when the processing tray pivots upward.

8. The post-processing unit for an image forming apparatus according to claim 5 , wherein a second slope is provided on a portion of the lock member on which the recording medium depressing member abuts when the processing tray pivots upward.