Image forming apparatus and image forming method

An image forming apparatus comprising:

• a plurality of electron-emitting devices arranged in a matrix using a plurality of first and second wirings;
• a light-emitting substance for emitting light by irradiation of electrons emitted by said electron-emitting devices;
• a first driving circuit for applying a scanning selection potential to selected first wirings and for applying a non-selection potential to first wirings other than said selected first wirings;
• a second driving circuit for applying a driving potential corresponding to an image signal to said plurality of second wirings;
• an offset voltage generating unit for generating a potential Vy′ by adding an offset potential Vb to said driving potential,
• wherein said offset voltage generating unit generates the potential Vy′ in accordance with the following condition,
• Vx<Vy′ and Vy′≈Vth,
• where Vth represents a threshold voltage to be applied to an electron-emitting device for emitting electrons needed for the light-emitting substance to emit light, Vx represents a potential difference between a maximum potential corresponding to a maximum luminance level and a minimum potential corresponding to a minimum luminance level among driving potentials selectable based on luminance of the image signal, and Vy′ represents a potential difference between the minimum potential and the scanning selection potential.

A driving circuit of an image forming apparatus having a plurality of electron-emitting devices arranged in a matrix using a plurality of first and second wirings and a light-emitting substance for emitting light by irradiation of electrons emitted by said electron-emitting devices, said circuit comprising:

• a first driving circuit for applying a scanning selection potential to selected first wirings and for applying a non-selection potential to said first wirings other than the selected first wirings;
• and
• a second driving circuit for applying a driving potential corresponding to an image signal to the plurality of second wirings,
• wherein said first and second driving circuits drives the plurality of electron-emitting devices in accordance with the following condition,
• Vx<Vy′ and Vy′>Vth,
• where Vth represents a threshold voltage to be applied to an electron-emitting device for emitting electrons needed for the light-emitting substance to emit light, Vx represents a potential difference between a maximum potential corresponding to a maximum luminance level and a minimum potential corresponding to a minimum luminance level among driving potentials selectable based on luminance of the image signal, and Vy′ represents a potential difference between the minimum potential and the scanning selection potential.

A driving circuit of an image forming apparatus having a plurality of electron-emitting devices arranged in a matrix using a plurality of first and second wirings and a light-emitting substance for emitting light by irradiation of electrons emitted by said electron-emitting devices, said circuit comprising:

• a first driving circuit for applying a scanning selection potential to selected first wirings and for applying a non-selection potential to the first wirings other than the selected first wirings;
• and
• a second driving circuit for applying a driving potential corresponding to an image signal to the plurality of second wirings;
• an offset voltage generating unit for generating a potential Vy′ by adding an offset potential Vb to said driving potential,
• wherein said offset voltage generating unit generates the potential Vy′ in accordance with the following condition,
• Vx<Vy′ and Vy′≈Vth,
• where Vth represents a threshold voltage to be applied to an electron-emitting device for emitting electrons needed for the light-emitting substance to emit light, Vx represents a potential difference between a maximum potential corresponding to a maximum luminance level and a minimum potential corresponding to a minimum luminance level among driving potentials selectable based on luminance of the image signal, and Vy′ represents a potential difference between the minimum potential and the scanning selection potential.

A driving method for driving an image forming apparatus having a plurality of electron-emitting devices arranged in a matrix using a plurality of first and second wirings and a light-emitting substance for emitting light by irradiation of electrons emitted by the electron-emitting devices, said method comprising the steps of:

• applying a scanning selection potential to selected first wirings and applying a non-selection potential to first wirings other than the selected first wirings;
• and
• applying a driving potential corresponding to an image signal to the plurality of second wirings,
• wherein said applying steps drive the plurality of electron-emitting devices in accordance with the following condition,
• Vx<Vy′ and Vy′>Vth,
• where Vth represents a threshold voltage to be applied to an electron-emitting device for emitting electrons needed for the light-emitting substance to emit light, Vx represents a potential difference between a maximum potential corresponding to a maximum luminance level and a minimum potential corresponding to a minimum luminance level among driving potentials selectable based on luminance of the image signal, and Vy′ represents a potential difference between the minimum potential and the scanning selection potential.

A driving method for driving an image forming apparatus having a plurality of electron-emitting devices arranged in a matrix using a plurality of first and second wirings and a light-emitting substance for emitting light by irradiation of electrons emitted by the electron-emitting devices, said method comprising the steps of:

• applying a scanning selection potential to a plurality of first wirings and applying a non-selection potential to the first wirings other than the selected first wirings;
• applying a driving potential corresponding to an image signal to the plurality of second wirings;
• and
• generating a potential Vy′ by adding an offset potential Vb to said driving potential,
• wherein said offset potential Vy′ is generated in accordance with the following condition,
• Vx<Vy′ and Vy′≈Vth,
• where Vth represents a threshold voltage to be applied to an electron-emitting device for emitting electrons needed for the light-emitting substance to emit light, Vx represents a potential difference between a maximum potential corresponding to a maximum luminance level and a minimum potential corresponding to a minimum luminance level among driving potentials selectable based on luminance of the image signal, and Vy′ represents a potential difference between the minimum potential and the scanning selection potential.