Patent ID: 7307606

Claim:
An image forming apparatus including a plurality of electron-emitting devices wired in a matrix, and fluorescent substances for emitting light by electrons emitted by the electron-emitting devices, further comprising: a circuit configured to output an image signal, based on an input image signal, wherein a frame rate of an image formed by the image signal is higher than a frame rate of the input image signal, wherein the image signal output by said circuit satisfies the following conditions: x is a normalized driving time period normalized to a maximum time period, during which time the fluorescent substances are continuously irradiated with electrons emitted from the electron-emitting devices driven by the image signal output from said circuit, y is a normalized luminance normalized to an amount of light emitted by the fluorescent substances, resulting from irradiation by electrons emitted from the electron-emitting devices in the maximum time period, in a graph whose abscissa x and ordinate y, a plurality of normalized luminance points which are measured at a plurality of driving time periods, each of which has equal time intervals less than 5 μs are plotted on the graph, wherein the plurality of driving time periods do not include x=0 and x=1, the number of normalized luminance points not falling within a range defined by lines y=x and y=x 0.8 on the graph, wherein the range includes a border, is 4/15 or less of the number of the plurality of normalized luminance points; a plurality of memories including a first memory and a second memory, each of which is configured to store a part of the image signals of one line of the image; a controller configured to control reading of the image signals from said plurality of memories; and a plurality of shift registers including a first shift register and a second shift register, the first shift register is configured to input an image signal output from the first memory, and said second shift register is configured to input an image signal output from the second memory.