Image sensing apparatus and method
AssigneeCanon Kabushiki Kaisha
InventorsAtsushi Ohtani, Yasuhide Ueno, Masashi Kimura
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Abstract
An image sensing apparatus senses an image by illuminating a document by a light source including three light emitting diodes which emit light of red, green, and blue so that the light reflected from the document is incident on a sensor array which in turn generates an electric signal corresponding to the incident light, wherein a predetermined light emitting diode is also turned on during a period in which no image sensing operation is performed thereby making it possible to stabilize the intensity of light illuminating an image. Thus, the invention provides a high-performance and small-sized image sensing apparatus at a low cost.
Claims57
An image sensing apparatus comprising:
- (a) a light source which emits a first light, a second light, and a third light which are different in wavelength;
- and
- (b) a sensing unit which, in response to the trigger signal for triggering an operation of sensing one line of an image, outputs in a first period, a signal of one line of an image illuminated with the emitted light,
- wherein the first light, the second light, and the third light are continuously turned on and off in this order in the first period, and the first light, the second light, and the third light are continuously turned on and off in this order in a second period during which the trigger signal is not generated over a length of time greater than the first period.
A method of sensing an image, comprising the steps of:
- (a) generating a trigger signal for triggering an operation of sensing one line of an image;
- (b) continuously turning on and off a first, a second, and a third light in a one-line sensing period, wherein the first light, the second light, and the third light are different in wavelength;
- (c) in response to the trigger signal, outputting in a first period, a signal of one line of the image illuminated with the emitted light;
- and
- (d) continuously turning on and off the first light, the second light, and the third light in this order in a second period during which the trigger signal is not generated over a length of time greater than the first period.
A control memory in which is stored a program comprising the steps of:
- (a) generating a trigger signal for triggering an operation of sensing one line of an image;
- (b) continuously turning on and off a first, a second, and a third light in a one-line sensing period, wherein the first light, the second light, and the third light are different in wavelength;
- (c) in response to the trigger signal, oputputting, in a first period, a signal of one line of the image illuminated with the emitted light;
- and
- (d) continuously turning on and off the first, the second, and the third light in this order in a second period during which the trigger signal is not generated over a length of time greater than the first period.
An image sensing apparatus comprising:
- (a) a light source which emits a first light, a second light and a third light which are different in wavelength;
- and
- (b) a sensing unit which accumulates valid data of an image illuminated with the emitted light in a first period in response to a trigger signal for triggering an operation of sensing one line of an image, and accumulates invalid data in a second period,
- wherein the first light, the second light, and the third light are continuously turned on and off in this order in the first second period, and the first light is turned on in the beginning of the first period in a case that the trigger signal is generated in the second period.
A method of sensing an image, comprising the steps of:
- (a) emitting a first, a second, and a third light which are different in wavelength;
- (b) generating a trigger signal for triggering an operation of sensing one line of an image;
- (c) accumulating valid data of the image illuminating with the emitted light in a first period in response to the trigger signal and invalid data in a second period;
- (d) continuously turning on and off the first light, the second light, and the third light in this order in the first and second period;
- and
- (e) turning on the first light in the beginning of the first period in a case that the trigger signal is generated in the second period.
A control memory in which is stored a program comprising the steps of:
- (a) emitting a first, a second, a third light which are different in wavelength;
- (b) generating a trigger signal for triggering an operation of sensing one line of an image;
- (c) accumulating valid data of the image illuminated with the emitted light in a first period in response to the trigger signal and invalid data in a second period;
- (d) continuously turning on and off the first light, the second light, and the third light in this order in the first and second period;
- and
- (e) turning on the first light in the beginning of the first period in a case that the trigger signal is generated in the second period.
Dependencies are inferred from the claim text.