Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
2001-11-27
2004-06-22
Mancuso, Joseph (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C341S139000, C345S163000
Reexamination Certificate
active
06753851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical mouse having a dynamic range, and more particularly to an optical mouse having a dynamic range, which is capable of adjusting an input range of an analog/digital (A/D) converter on the basis of a magnitude variation of an output signal from the A/D converter to increase a resolution of the A/D converter relative to a low illumination range or fine illumination range, thereby improving the ability of the converter to sense a fine signal variation.
2. Description of the Related Art
An optical mouse generally comprises an image sensor for sensing an image of a motion and outputting the resulting image signal, an A/D converter for converting the image signal from the image sensor into digital data, an image processor for performing a signal processing operation for the digital data from the A/D converter to detect the motion therefrom, and a controller for providing data corresponding to the detected motion to a computer.
Note that the A/D converter in the optical mouse has a fixed input range. With the A/D converter having the fixed input range, the optical mouse can desirably obtain a relatively accurate image in the case of inputting a signal of an amount of light within a certain range, but has the disadvantage of being incapable of obtaining an accurate image in the case of inputting a signal of an amount of light beyond the certain range. In order to make up for this problem, automatic gain control means is generally used to limit a signal magnitude of input light to the optical mouse.
FIG. 1
is a block diagram showing a circuit construction of a conventional optical mouse. As shown in this drawing, the conventional optical mouse comprises a light source
11
for emitting light to an object
1
such as a mouse pad, an image sensor
12
for sensing an image of the object
1
, a shutter/controller unit
13
for limiting the magnitude of the image signal from the image sensor
12
, an A/D converter
14
for converting an analog image signal from the shutter/controller unit
13
into digital image data, an image data processor
15
for processing the image data from the A/D converter
14
to detect motion data therefrom, and a system controller
16
for sending the motion data from the image data processor
15
to a computer.
In the above-mentioned conventional optical mouse, an input signal under the condition of an appropriate illumination or of incident light of high intensity has such a sufficient variation as to be converted according to a predetermined resolution of the A/D converter. Alternatively, where the incident light is small in amount, the shutter is opened for a period of time long enough to adjust a dark object to a proper brightness, but the input signal becomes that much smaller in variation. In other words, the dark object is extremely small in reflected light amount, resulting in there being a very small difference between a noise level and a signal level. As a result, provided that a signal incoming from the object is amplified, it will become a signal as shown in
FIG. 2
a
because a noise level is also amplified, although the figure of the object is well visible. If the object is accurately centered on the image sensor, this sensor will provide a signal distribution as shown in
FIG. 2
b
. For the effective detection of a motion by the optical mouse, it is preferable that a detected signal has a magnitude distributed uniformly over the entire input range of the A/D converter. However, in the case where the detected signal is under the condition of a low illumination, the magnitude thereof leans to a certain level of the entire input range of the A/D converter, or a low level.
By opening the shutter for a lengthy period of time under the above condition, the signal magnitude can be increased from a signal distribution SD
1
to SD
2
as shown in
FIG. 2
c
. It is preferable that the detected signal varies over the entire input range of the A/D converter, but it varies over a small range under the condition of a low illumination. This signifies that an 8-bit A/D converter provides its output signal having a variation of, for example, 4 bits.
In other words, the magnitude of the detected signal input to the A/D converter
14
varies with an image, or light and dark regions on the pad for the optical mouse. Where the light and dark regions of the pad have a low contrast, the magnitude of the detected signal is distributed concentratedly (referred to hereinafter as ‘data concentrated distribution’) at a certain level of the entire input range of the A/D converter
14
. For example, the data concentrated distribution may be present at any one of a high level, middle level and low level of the entire input range of the A/D converter
14
.
Provided that the data concentrated distribution occurs as described above, the data magnitude will have a fine variation, thereby making it difficult for the optical mouse to detect a motion. In this case, there is a need for a technique to adjust the input range of the A/D converter about the level at which the data concentrated distribution occurs, thereby enabling the optical mouse to detect a fine motion.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical mouse having a dynamic range, which is capable of adjusting an input range of an analog/digital converter on the basis of a magnitude variation of an output signal from the analog/digital converter to increase a resolution of the analog/digital converter relative to a low illumination range or fine illumination range, thereby improving the ability of the converter to sense a fine signal variation.
In accordance with the present invention, the above and other objects can be accomplished by the provision of an optical mouse having a dynamic range, comprising analog/digital (A/D) conversion means having an input range adjusted based on an input range control signal, the A/D conversion means receiving an input signal over the adjusted input range and converting the received signal into digital data; and image data processing means for determining on the basis of image data from the A/D conversion means whether a data concentrated distribution has occurred, detecting a level of the input range with the data concentrated distribution upon determining that the data concentrated distribution has occurred, outputting the input range control signal to the A/D conversion means according to the detected level and processing the image data from the A/D conversion means to detect motion data therefrom.
Preferably, the image data processing means may subdivide a data concentrated distribution degree (data concentration degree) related to a magnitude variation of a detected signal and determine the input range of the A/D conversion means on the basis of the data concentration degree. In this case, the input range of the A/D conversion means can be adjusted more precisely centering around a data concentrated distribution area. Further, the resolution of the A/D conversion means is applied to a small, adjusted input range relative to the entire input range of the A/D conversion means, so that it can be increased relatively. Therefore, the A/D conversion means can detect a fine magnitude variation of the detected signal.
REFERENCES:
patent: 4771267 (1988-09-01), Russell, Jr. et al.
patent: 5973674 (1999-10-01), Buecker
patent: 2002/0080247 (2002-06-01), Takahashi et al.
Choi Won-Tae
Lee Bang-Won
LeFlore Laurel E.
Lowe Hauptman & Gilman & Berner LLP
Mancuso Joseph
Samsung Electro-Mechanics Co. Ltd.
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