B6TS Touch Sensing IC
Capacitive Touch Sensing ICs and the Appliance
Industry
WHITE PAPER
OMRON created the B6T series of touch-sensing ICs, to offer an
extremely fast methodology for developing an appliance touch panel and
firmware, to implement its operation;
this occurs in the briefest period of time.
Thus, OMRON is making use of its expertise & know-how, in the form of software,
to allow for quick product development. The B6T series offers a circuit design
support tool called the Workbench, which has eliminated the need for
expertise
or know-how
in the analog circuitry required for installation in devices
and
allows
simple use, by anybody, with a basic knowledge of digital circuitry.
In the appliance industry, the above relates to a quick turn-around, when a
new product platform is in-place, with a tight-schedule. Once the touch panel is
designed, the development time, regarding the firmware, can be reduced to
hours & days, from weeks & months!
The B6T series has integrated detecting and processing functions, into a
single-chip IC; this makes it possible to adjust sensitivity, using software. The
above achieves a highly-reliable package, including noise processing, and
operating environment compensation while maintaining excellent flexibility.
Overview
In the case of the 4-channel device, the chip is a sensing IC to detect micro
capacitances and can be used in appliance touch sensing panels. Internally, the
chip employs the 16 bit CMOS process and is contained in a 20-pin SSOP plastic
package. The IC has 4 independent measurement pins, each of which can
measure capacitance independently. On/off output or serial communication
output can be selected as the output form. The IC is provided with an EEPROM
that can stores the end-customer’s parameter set;
this would include momentary
vs. toggle, threshold levels, single vs. serial output mode, to name a few.
The IC is available in 4 and 8 channel, with the 16 channel available the
beginning of 2007. The 8 channel B6TS IC is appropriate for use in laundry
controls, refrigeration, range hoods, dish washers, and other designs where the
input count is applicable.
To minimize the cost of the finished system, low-cost commercial
single-sided PCB materials - such as FR-4, FR-2 or CEM-1 can be used. For
non-flat user interfaces, FPCs (Flexible Printed Circuit) can be used to build
© OMRON Electronic Components LLC
Steve Massie – August 2006
1
B6TS Touch Sensing IC
unique design touch panel solutions. Touch keys can be produced using any
non-conducting panel material including plastic, rubber, glass, marble, and wood.
The B6TS sensor chips allow you to create exciting solutions with various
materials, graphics and special lighting effects that will let your product stand out.
The above permits an appliance maker to create the same “look”, as the other
products built. B6Ts also allow for backlighting and clear sensing solutions with
ITO and other clear materials to create backlight touch keys for special effects.
Touch switches over LCD and LED backlighting and cost-effective multi-key
solutions, which can enhance appliance panel designs.
As can be observed, the product line functions, line-up as follows:
•
•
Runs on Windows PCs (Windows XP and 2000 recommended)
Connects with a PC, via serial communication
o
Parameter setting function
o
Operation monitor function
o
Capacitance calculation function
Comes with an evaluation board for four or eight channels for
immediate evaluation:
Four channels: B6TW-S04LT
Eight channels: B6TW-S08NF
Twelve Channels:
Coming in February, 2007
•
•
•
•
The basic ground-loop capacitance design is a follows:
© OMRON Electronic Components LLC
Steve Massie – August 2006
2
B6TS Touch Sensing IC
© OMRON Electronic Components LLC
Steve Massie – August 2006
3
B6TS Touch Sensing IC
Generally, measurement of capacitance value, C, requires conversion of the value into an
electrical signal such as a frequency, voltage, etc. For B6T, the value Cx is converted
into voltage. Although various methods are available for converting capacitance into
voltage, B6T series uses the “series capacitance division comparison system” (patent
pending). When the voltage on pin A of B6T is represented with Va and the voltage on
pin B with Vb, measuring Vb allows detection of change in an unknown capacitance
value, Cx.
Specifically, the voltage ratio of the fixed capacitance value Cr to the varying and
unknown capacitance value Cx is measured. Under this method, measuring change in
the voltage ratio detects the capacitance change generated by the approach of a person
to the electrode, which allows sensing of whether a person has touched the electrode.
© OMRON Electronic Components LLC
Steve Massie – August 2006
4
B6TS Touch Sensing IC
As mentioned earlier, development time is pivotal for the B6T, thus, the OMRON
Workbench software,
the development flowchart,
is briefly stated below. The 1
st
step of
appearance design
is simply the design of the touch panel. The circuit
design/circuit constants are derived from the OMRON development software.
Step 4 is a result of real time usage of the Workbench development kit.
Pin assignment for the 4-channel IC.
Pin functions
© OMRON Electronic Components LLC
Steve Massie – August 2006
5
京公网安备 11010802033920号
EEWORLD
