Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Impedance or current regulator in the supply circuit
Reexamination Certificate
2000-03-30
2001-11-06
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Impedance or current regulator in the supply circuit
C315S307000, C315S149000, C315S158000
Reexamination Certificate
active
06313586
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a control apparatus for controlling a light source and, more particularly, to a control apparatus for controlling a luminous energy of the light source in an image input apparatus.
In general, an image input apparatus is provided with a cold-cathode tube light source (CCFL) and a read-in solid imaging device (CCD). In the image input apparatus, the CCFL irradiates a light to a document paper in order to read the image from the document paper by the CCD. On reading the image from the document paper by the CCD, it is necessary to properly control a luminous energy of the CCFL.
When the CCFL is put into an on-state in a conventional image input apparatus, the luminous energy reaches a predetermined energy in the CCFL after a predetermined time lapses. After the luminous energy reaches the predetermined energy in the CCFL, the conventional image input apparatus starts to read the image from the document paper by the CCD to obtain the image. More particularly, a time duration lapse needs until the luminous energy reaches the predetermined energy in the CCFL after the CCFL is put into an on-state. The time duration lapse will be called a rise time. The rise time is determined on the basis of a characteristic of CCFL. As described above, the conventional image input apparatus starts to read the image from the document paper by the CCD after the luminous energy is stabilized.
As described above, it is necessary to start to read the image from the document paper in the conventional image input apparatus after the luminous energy is stabilized in CCFL. In other words, it is impossible to start to read the image from the document paper in the conventional image input apparatus until the luminous energy is stabilized in CCFL. As a result, a user must wait to read the image from the document paper after the luminous energy is stabilized in CCFL.
In order to read the image from the document paper at once after the CCFL is put into the on-state, an environmental temperature of the CCFL may be kept at a predetermined temperature. More particularly, the environmental temperature of the CCFL is controlled to the predetermined temperature by a heater system. However, a waiting or stand-by consumption power increases when the environmental temperature of the CCFL is controlled to the predetermined temperature by the heater system.
Furthermore, a fluorescent tube may be used as the light source instead of the CCFL. The fluorescent tube is constituted by only an inert gas and does not contain mercury or the like having a high dependency on a tube temperature. When the fluorescent tube is used as the light source instead of the CCFL, it is difficult to obtain a sufficient luminous energy although a rise time characteristic is improved.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a light source control unit capable of obtaining a sufficient luminous energy without increasing a stand-by consumption power.
It is another object of this invention to provide a light source control unit capable of improving a rise time characteristic without increasing a stand-by consumption power.
Other objects of this invention will become clear as the description proceeds.
On describing the gist of this invention, it is possible to understand that a light source control apparatus is for use in an image input apparatus comprising a cold cathode tube light source and a solid imaging device. The image input apparatus reads an image from a document paper by receiving at the solid imaging device a reflected light which is obtained by reflecting a light of the cold cathode tube light source on the document paper.
According to this invention, the light source control apparatus comprises control means for, in accordance with a feedback signal, controlling a current as a tube current which is applied to the cold cathode tube light source and feedback means for feeding back an output of the solid imaging device as the feedback signal to the control means.
REFERENCES:
patent: 5198909 (1993-03-01), Ogiwara et al.
patent: 5907742 (1999-05-01), Johnson et al.
patent: 6069448 (2000-05-01), Yeh
Okazaki Yutaka
Shimizu Tatsuya
Yamamoto Tetsuichiro
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Philogene Haissa
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