Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-05-26
2001-12-11
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C382S274000
Reexamination Certificate
active
06330083
ABSTRACT:
This application is based on applications Nos. 9-138635 and 9-217370 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to image reading devices for use in, for example, copying machines and facsimiles, and in particular, to an image reading device which is adapted to continuously read large amounts of documents using a light source such as a fluorescent lamp whose light quantity varies depending on an ambient temperature and other factors.
Conventionally, light quantity correction of a light source for illuminating a document has been executed at a constant frequency, i.e., at constant intervals, even if a copying mode (eg. a high image quality mode and a high production mode) differs.
For example, if the light quantity correcting frequency is adjusted to a high image quality mode, the light quantity correction operation is performed frequently such that the image quality is maintained high. However, such frequent light quantity corrections require comparatively much time. Accordingly, disadvantageously, a productivity in the high production mode is reduced. Conversely, if the light quantity correcting frequency is adjusted to the high production mode, there is a problem that the image quality in the high image quality mode may deteriorate.
Also, there is known a device which absorbs fluctuation in light quantity of a light source by adjusting the light quantity of the light source every time a document page is read (Japanese Patent Publication No. HEI 5-30102).
However, performing a light quantity adjustment so frequently leads to a problem that a warm-up time and a read time for a first copy become long, causing a reduction in productivity.
There is a further concern that the fluctuation in light quantity would be conversely increased by frequently executing the light quantity adjustment. For example, if the light quantity considerably decreases during a continuous read operation and thus the decrease in light quantity is corrected, a light quantity adjustment value, i.e., a lighting control value may considerably increase. Accordingly, upon lighting the light source again after an environmental temperature has decreased after completion of the above continuous read operation, there may be a saturation in light quantity of the light source.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an image reading device and method capable of executing a light quantity correcting operation corresponding to a set mode.
Another object of the present invention is to provide an image reading device and method capable of compensating for a fluctuation in light quantity due to deterioration with time of a light source, without requiring frequent light quantity adjustment operations, thereby allowing the productivity to be compatible with the image quality.
A further object of the present invention is to provide a lighting device and method capable of changing timing of detecting light quantity of a light source illuminating an object such as a document, so that the light quantity of the light source is corrected with a variable timing.
According to an aspect of the present invention, there is provided an image reading device which essentially includes a light source, such as a fluorescent lamp, for illuminating a document, an image reader for reading the illuminated document and outputting an image signal, light quantity detecting means for detecting a light quantity of the light source, light quantity correcting means for correcting a fluctuation in light quantity of the light source based on the light quantity detected by the light quantity detecting means, and light quantity detection timing changing means for changing a timing of light quantity detection by the light quantity detecting means.
In this image reading device, a document is read while being illuminated and then an image signal is output. A quantity of light illuminating the document is detected with a specified timing. Then, a fluctuation in light illuminating the document is corrected based on the detected light quantity. The above timing of light quantity detection is changeable.
In an embodiment, the image reading device includes counting means for counting a number of document read operations performed by the image reader. Then, the timing of light quantity detection is changed according to the number of document read operations counted by the counting means.
In an embodiment, the image reading device includes mode setting means for selecting one out of a plurality of modes and setting the selected mode. In this case, the timing of light quantity detection is changed according to the mode set by the mode setting means.
The modes may include a high image quality mode in which the image signal is directly output to outside without being stored in a storage and a high production mode in which the image signal is once stored in the storage and then output to the outside.
The present invention also provides an image reading device comprising:
a light source for illuminating a document;
a photoelectric converting section for converting a reflection light from the document into an analog electric signal;
a signal converting section for converting the analog electric signal into a digital signal;
light quantity detecting means for detecting a light quantity of the light source;
light quantity correcting means for correcting a fluctuation in light quantity of the illuminating means based on the light quantity detected by the light quantity detecting means;
mode setting means for selecting one out of a plurality of modes and setting the selected mode; and
light quantity detection timing changing means for changing a timing of light quantity detection by the light quantity detecting means according to the mode set by the mode setting means.
According to a further aspect of the present invention, there is provided a lighting device which essentially comprises a light source for illuminating an object, light quantity detecting means for detecting a light quantity of the light source, light quantity correcting means for correcting a fluctuation in light quantity of the light source based on the light quantity detected by the light quantity detecting means and light quantity detection timing changing means for changing a timing of light quantity detection by the eight quantity detecting means.
In the lighting device, an object, such as a document, is illuminated by the light source. Then, a quantity of light illuminating the object is detected with a specified timing. Then, a fluctuation in light illuminating the object is corrected based on the detected light quantity. The above timing of light quantity detection is changeable.
In an embodiment, the lighting device also includes light quantity variation characteristic detecting means for detecting a variation characteristic of the light quantity from a time at which the light source is turned on. In this case, the timing of light quantity detection is changed according to the detected light quantity variation characteristic.
In an embodiment, the timing of light quantity detection is changed according to a duration of an illuminating time of the light source.
In still another aspect of the invention, there is provided a lighting device comprising:
a light source for illuminating a document;
light quantity detecting means for detecting a light quantity of the light source; and
light quantity correcting means for predicting a fluctuation in light quantity based on a history of the light quantity detected by the light quantity detecting means, and correcting the light quantity of the light source to the predicted light quantity.
The lighting device of any one of the above embodiments together with an image reader will provide an improved image reading device applicable to a copying machine, a facsimile device, etc.
REFERENCES:
patent: 4926253 (1990-05-01), Nakashima
patent: 4931882 (1990-06-01), Takeda
patent: 5513018 (1996-04-01), Nisimura
patent: 5717790 (1998-0
Nabeshima Takayuki
Tajima Katsuaki
Burns Doane , Swecker, Mathis LLP
Grant II Jerome
Minolta Co. , Ltd.
Worku Negussie
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