Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-02-10
2001-05-29
Phan, James (Department: 2872)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C355S030000, C362S006000
Reexamination Certificate
active
06239884
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanner and a control method for controlling lighting a cold-cathode tube which is a light source of the scanner.
2. Description of the Related Art
FIGS. 4A and 4B
show the configuration of a conventional type scanner connected to a computer and others and used for a reader for reading an image on a manuscript.
As shown in
FIG. 4A
, in the conventional type scanner
1
, an image sensor not shown for reading a manuscript
50
is installed so that it can indirectly read the manuscript via a lighting plate
52
.
Also, a cold-cathode tube, for example, a cold-cathode fluorescent lamp
20
is mainly provided between the lighting plate
52
and the manuscript to enhance resolution when the manuscript
50
is read and a pre-heater
30
is provided for pre-heating the cold-cathode fluorescent lamp
20
.
Referring to the drawings, the cold-cathode fluorescent lamp
20
and the pre-heater
30
will be described below.
FIG. 4B
is a sectional view showing the configuration of the cold-cathode fluorescent lamp of a scanner shown in FIG.
4
A.
As shown in
FIG. 4B
, the cold-cathode fluorescent lamp
20
is formed by applying fluorescent paint to a part of the inner wall of a bulb
2
a
made of quartz and depositing or applying reflection coatings
2
b
and
2
c
on the outside face corresponding to the applied area of the above bulb
2
a
. Hereby, the cold-cathode fluorescent lamp has directivity of emitting all light emitted from the cold-cathode fluorescent lamp
20
from a radiation aperture
2
d
provided by the reflection coatings
2
b
and
2
c
. The pre-heater
30
for preheating the cold-cathode fluorescent lamp
20
to predetermined temperature is attached to the whole surface of the reflection coating
2
c.
Even if the cold-cathode fluorescent lamp
20
is used under a low-temperature condition, luminance to an extent required for a light source for scanner can be acquired by energizing the pre-heater
30
and increasing the surface temperature of the cold-cathode fluorescent lamp
20
up to approximately 50° C. by the pre-heater
30
.
The conventional type scanner has the following problems.
The cold-cathode fluorescent lamp used in the conventional type scanner has a defect in a temperature characteristic that the quantity of light and the luminance of the cold-cathode fluorescent lamp do not become stable unless fixed time elapses after the cold-cathode fluorescent lamp is lighted because gas filled inside is not stable at low temperature.
The above characteristic causes a defect that unless only the cold-cathode fluorescent lamp is lighted beforehand and normal reading operation is started after time elapses to some extent if a scanner is used, an image sensor cannot fetch a stable image.
Also, to supplement the above defects, there is a method of always lighting only the cold-cathode fluorescent lamp even while a scanner is not used and immediately realizing normal operation when an image is read; however, there is a defect that as the cold-cathode fluorescent lamp is lighted even when a scanner is unused, power is often uselessly consumed.
Also, only when a manuscript is scanned, the cold-cathode fluorescent lamp can be immediately lighted by providing the above pre-heater and always heating the cold-cathode fluorescent lamp in place of always lighting the cold-cathode fluorescent lamp. However, in this case, as the pre-heater is driven as long as the power source of the scanner is turned on, power is greatly wasted.
SUMMARY OF THE INVENTION
The present invention is made in view of the above problems in prior art and the object is to provide a scanner and a method of controlling lighting a cold-cathode tube of the scanner wherein enough operation is enabled, saving the power consumption of the cold-cathode tube and a pre-heater.
Further, another object of the present invention is to provide a scanner wherein the above object can be achieved with simple configuration.
A scanner according to a first invention includes a cold-cathode tube for emitting light in a manuscript reading position where an image on the manuscript is detected by an image sensor, a pre-heater for preheating the cold-cathode tube before the cold-cathode tube is lighted, a light source for detection connected to the pre-heater in series for detecting for emitting light toward the manuscript reading position to detect the end of the manuscript, a detecting element for detecting light emitted from the light source for detection and reflected in the manuscript reading position and generating a detection signal showing that the end of the manuscript is detected, and a driving circuit for controlling the lighting of the cold-cathode tube and the stop of the pre-heater according to the detection signal from the detecting element.
The lighting of the light source for detection and the preheat by the pre-heater can be controlled with common power by connecting the light source for detection for detecting the end of a manuscript to the pre-heater in series and in addition, the lighting of the light source for detection and preheating can be simultaneously started. Hereby, the individual control of the lighting of the light source for detection and preheat by the pre-heater is not required and wiring can be simplified. Also, the detection synchronous with preheating of a manuscript in the manuscript reading position is enabled.
The driving circuit controls the stop of the pre-heater when the detecting element detects the end of a manuscript while detecting manuscript reading operation by the scanner. Therefore, not only the wait time of the scanner in operation is reduced but also unnecessary electrification can be avoided and power consumption can be reduced.
In the present invention, if the pre-heater is connected to both ends of the light source for detection, not only power consumption is reduced but the area of the cold-cathode tube to which heat from the pre-heater is applied is increased and power used for the scanner can be efficiently utilized.
In the present invention, it is desirable that the pre-heater is provided in the vicinity of the surface (the shielding face) on the reverse side to the manuscript reading position based upon the cold-cathode tube. In this case, the light source for detection and the pre-heater can be prevented from intercepting light from the cold-cathode tube and reducing luminous radiation efficiency onto a manuscript.
In the present invention, the driving circuit is concretely connected to a series circuit composed of the pre-heater and the light source for detection and is provided with a first power supply circuit for supplying driving power for simultaneously enabling the preheat of the pre-heater and the lighting of the light source for detection and a second power supply circuit for lighting the cold-cathode tube. Further, the first power supply circuit is characterized in that it starts the supply of power before the second power supply circuit lights the cold-cathode tube and stops the supply of power according to a detection signal from the detecting element.
Hereby, the pre-heater and the cold-cathode tube can be independently driven. As the preheat of the pre-heater and the lighting of the light source for detection are stopped when the cold-cathode tube is lighted, there is no useless power consumption.
As the first power supply circuit starts the supply of power when a manuscript is first set, preheat can be started at the same time as the manuscript is set and useless power consumption is prevented.
A method of controlling lighting a cold-cathode tube in the scanner according to a second invention is characterized in that a pre-heater for preheating the cold-cathode tube and a light source for detection for detecting a manuscript are simultaneously energized. The method has the steps of: detecting a run of the manuscript; energizing the pre-heater for preheating the cold-cathode tube responsive to a detection of the run, and simultaneously energizing a light source for gene
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Phan James
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