Patent ID: 7894097

Claim:
An image forming apparatus, comprising: a main body of the image forming apparatus; an upper portion provided on the main body of the image forming apparatus, the upper portion being openable/closable relative to the main body; a sensor configured to detect an open/close state of the upper portion relative to the main body and output an open/close state signal; an operation panel configured to input instructions to control the image forming apparatus; a receiving unit configured to receive instructions from the operation panel; and a controller coupled to the sensor and the receiving unit and configured to control operation of the image forming apparatus, wherein after the upper portion has been opened, the controller determines a length of time between a receipt of the operational instruction and when the sensor detected that the upper portion was opened, and invalidates an operational instruction if the controller determines that the operational instruction has been received by the receiving unit from the operation panel within a predetermined period before the sensor detected that the upper portion was opened; wherein the upper portion includes an image reading unit configured to scan an image of a document sheet and a document sheet sensor configured to detect presence/absence of the document sheet to be scanned; wherein, when the controller receives a signal indicating presence of the document sheet from the document sheet sensor, the controller accepts an operational instruction received by the receiving unit to start scanning the image on the document sheet during a predetermined period after the controller received the closed state signal; and wherein, when the controller has not received the signal indicating presence of the document sheet from the document sheet sensor within the predetermined period after the controller received the closed state signal, the controller rejects the operational instruction if the controller determines that the operational instruction has been received by the receiving unit from the operation panel within the predetermined period after the controller received the closed state signal.