Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-09-08
2001-08-28
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S474000, C358S471000
Reexamination Certificate
active
06281991
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a self-illumination scanner apparatus which reads an image by illuminating a surface to be sensed including various kinds of optically readable images such as code patterns, characters, patterns, and the like printed on, e.g., a paper sheet using an illumination light-emitting member comprising an LED (light-emitting diode), and receiving light. reflected by the illuminated surface to be sensed.
Conventionally, various self-illumination scanner apparatuses of this type are known.
The assignee of the present invention has proposed a system for recording audio information on a recording medium such as a paper sheet in the form of a dot code which serves as image information, i.e., encoded information, that can be transmitted via a facsimile apparatus and can produce a large quantity of copies at low cost, and which is defined by a two-dimensional matrix of a plurality of dots, and also a system for reproducing the dot code, as disclosed in, e.g., EP0670555A1, which describes a self-illumination scanner apparatus for optically reading the dot code.
As an illumination light-emitting member for such self-illumination scanner apparatus, an LED is normally used since it is relatively inexpensive, is easily available, and can be driven at a lower voltage than other illumination light-emitting members.
However, LEDs have shortcomings, i.e., variations in internal resistance upon operation in units of elements.
For example, when a circuit arrangement shown in
FIG. 1
, i.e., a parallel circuit of a plurality of LEDs is used, the drive currents differ in units of elements at a ratio that depends on their internal resistance ratio, resulting in variations in the amount of light emitted by the respective LED elements.
As another shortcoming, since LEDs have variations in current-light amount conversion efficiency in units of elements, variations in drive current further promote variations in the amount of light emitted.
Consequently, when the circuit arrangement shown in
FIG. 1
is used as an illumination light-emitting member in the above-mentioned self-illumination scanner apparatus, even if the plurality of LEDs are disposed at equal angular intervals in an annular pattern around a solid-image image sensing element, the brightness on the surface to be sensed becomes nonuniform due to. variations in light amount emitted by the respective LED elements, and each dot in a dot code is hard to accurately recognize and read as a dot.
In order to solve such problem, a circuit arrangement as a series circuit of a plurality of LEDs shown in
FIG. 2
may be used.
According to this circuit arrangement, since the variations in internal resistance in units of LED elements are averaged by the serially connected LEDs, these variations can be suppressed consequently.
However, when the arrangement show in
FIG. 2
is used, a high voltage must be applied to a terminal A, and a high-voltage generation circuit must be added.
More specifically, in the arrangement of EP0670555A1, since a plurality of LEDs are controlled to emit light instantaneously, the drive current required for obtaining a necessary light amount becomes high.
The anode-cathode voltage of each LED nonlinearly increases with increasing current. For this reason, when three LEDs are connected in series with each other, as shown in, e.g.,
FIG. 2
, if a current of nearly 100 mA is applied to one column, the voltage across the terminals A and B becomes as high as about 7V due to the forward-bias voltage of the LEDs.
In practice, a drive circuit for the LEDs has an arrangement shown in FIG.
3
.
In this case, since a constant current circuit alone requires several V, a high voltage of at least 10V is required at the terminal A.
Also, when a solid-state image sensing element such as a charge coupled device (CCD) or the like exclusively used in the self-illumination scanner apparatus is driven, a high voltage is required since a capacitive load must be driven.
Hence, the power supply for the illumination LEDs may be commonly used as that for driving this solid-state image sensing element.
Unfortunately, since the power supply for the LEDs has a large sag owing to heavy instantaneous load upon light emission, direct use of the power supply for the solid-state image sensing element that requires a stable power supply as that for the LEDs is extremely unpreferable.
In view of the foregoing, in order to realize the circuit arrangement shown in
FIG. 2
, an additional high-voltage generation circuit is required. However, if this circuit is merely added, another problem, i.e., an increase in size or weight of the apparatus, is posed.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its object to provide a self-illumination scanner apparatus which can attain its size reduction by effectively using an existing predetermined power supply in the apparatus and a predetermined pulse used for driving a solid-state image sensing element, and can maximize the reading performance of an image such as a dot code or the like.
In order to achieve the above object, according to the first aspect of the present invention, there is provided a self-illumination scanner apparatus which comprises an illumination light-emitting member for illuminating a surface to be sensed including an image, a solid-state image sensing element for receiving light reflected by the surface to be sensed illuminated by the illumination light-emitting element, and generating an image signal corresponding to the image of the surface, and a drive circuit for controlling driving of the solid-state image sensing element to sense the image,
wherein the illumination light-emitting member is an LED group prepared by connecting a plurality of LEDs in series with each other, and
the apparatus comprises, as a power supply circuit for the illumination light-emitting member, a booster circuit for generating a high voltage by piling up a predetermined power supply voltage in the apparatus, and a frequency-divided pulse obtained by frequency-dividing a predetermined pulse output from the drive circuit.
Corresponding Embodiment of the Invention
The first, second, and third embodiments of the present invention correspond to the first aspect.
Not that a plurality of pulses to be used in an image sensing circuit with this arrangement are output in these embodiments. Also, a one-shot pulse may be added to a DC voltage.
Operation and Advantage
According to this arrangement, a self-illumination scanner apparatus which can attain a size reduction of the apparatus, and can maximize the reading performance of an image such as a dot code or the like can be provided.
Furthermore, this arrangement can be suitably used especially in a hand-held scanner apparatus.
According to the second aspect of the present invention, there is provided a self-illumination scanner apparatus wherein the predetermined power supply voltage in the apparatus is a power supply voltage to be supplied to at least one of the solid-state image sensing element and drive circuit before it is boosted to a voltage value required in at least one of the solid-state image sensing element and drive circuit, in the arrangement of the first aspect.
Corresponding Embodiments of the Invention
The first embodiment of the present invention corresponds to the second aspect.
Operation and Advantage
According to this arrangement, in addition to the advantage of the first aspect, a self-illumination scanner apparatus which can effectively use an existing power supply without adversely influencing the operation of the solid-state image sensing element and the like can be provided.
According to the third aspect of the present invention, there is provided a self-illumination scanner apparatus, wherein the booster circuit piles on and outputs a plurality of frequency-divided pulses having different phases as the frequency-divided pulses, in the arrangement of the first aspect.
Corresponding Embodiments of the Invention
The first embodiment
Ishimoto Kazuo
Mori Takeshi
Watanabe Tohru
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Lee Cheukfan
Olympus Optical Co,. Ltd.
LandOfFree
Self-Illumination scanner apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-Illumination scanner apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-Illumination scanner apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513773