Scanner that controls stepping motor torque

Details Scanner that controls stepping motor torque Scanner that controls stepping motor torque

2000-12-21

2002-07-02

Ro, Bentsu (Department: 2837)

Electricity: motive power systems

Open-loop stepping motor control systems

C358S423000

Reexamination Certificate

active

06414461

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to scanner. More specifically, the present invention relates to a scanner that controls stepping motor torque.
2. Description of the Prior Art
Computers have become increasingly ubiquitous in almost all aspects of life, from home to office. With the growth of computers, the requirements of personal image processing are increasing. Scanners are therefore becoming more and more popular. And, for catering to the various image requirements of users, scanners have to offer the users various resolution options. When using a scanner, users can choose a suitable resolution to scan documents or pictures. For example, when a user generates icons for a homepage, he or she will choose a lower scanning resolution. For high quality digital images, a higher resolution will be chosen.
Please refer to FIG.
1
and FIG.
2
.
FIG. 1
is a function block diagram of a prior art scanner
10
.
FIG. 2
is a schematic circuit diagram of the scanner
10
of FIG.
1
. The scanner
10
comprises a scanning module
12
, a stepping motor
16
, and a control circuit
18
. The scanning module
12
is used to scan a document and generate image data. The control circuit
18
controls the stepping motor
16
to generate a torque for driving the scanning module
12
. As shown in
FIG. 2
, when control circuit
18
drives the scanning module
12
, it applies a voltage to the stepping motor
16
, activating the stepping motor
16
. When the stepping motor
16
operates in a steady-state condition, the current of the stepping motor
16
is fixed, and the torque of the stepping motor
16
, thus, is fixed. A consequence of this is that, when the scanning module
12
scans the document at a high resolution, the stepping motor
16
generates a surplus torque that causes excessive noise and shock. This excessive noise and shock influences the quality of the image generated by the scanner
10
.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a scanner that controls the torque of the stepping motor. The scanner uses a suitable torque when scanning a document.
In a first embodiment of the present invention, the scanner comprises a scanning module for scanning a document, a driving module for driving the scanning module, and a control circuit for controlling the scanner. The driving module comprises a stepping motor for driving the scanning module forward and backward. The control circuit controls the current of the stepping motor and thus controls the torque that the stepping motor produces.
In a second embodiment of the present invention, the control circuit further comprises a driving program, a processor for executing the driving program, and a memory for storing a torque table. The torque table records a plurality of torque values. Each of the torque values corresponds to a predetermined condition when the stepping motor produces a torque. When the driving program is executed, the driving program chooses one of the torque values according to the predetermined condition, and transmits a driving signal to the driving module. The stepping motor of the driving module generates a suitable torque according to the driving signal, and then drives the scanning module.
It is an advantage of the present invention that the stepping motor of the scanner generates a suitable torque to drive the scanning module according to a resolution that the scanning module uses. Therefore, the stepping motor does not generate excessive torque.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.


REFERENCES:
patent: 5745254 (1998-04-01), Satou
patent: 6101006 (2000-08-01), Bryant et al.
patent: 6115149 (2000-09-01), Lai et al.

Affiliated with

Also associated with

Rating

Scanner that controls stepping motor torque does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Scanner that controls stepping motor torque, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scanner that controls stepping motor torque will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2909553