Object counter and identification system

A system for counting the number of objects of known thickness in a stack and identifying the objects by their color in which an ultrasonic sensor is mounted at a known distance from a reference point that defines the beginning of the stack. The ultrasonic sensor is operated to measure the round trip transit time of ultrasonic energy reflected back from the closest object in the stack and the number of objects in the stack is calculated on the basis of the known distance and the round trip transit time. A color sensor senses the color of at least one object in the stack to identify the object. In a casino application where the objects are chips of known monetary value, the value of the chips in the stack can be calculated.

FIELD OF THE INVENTION 
The present invention is directed to the field of automatically counting 
the number of objects in a stack and identifying the objects on the basis 
of a color characteristic. 
BACKGROUND OF THE INVENTION 
A need sometimes exists to count a plurality of objects in a stack and to 
identify the type of each object in the stack on the basis of a certain 
characteristic, for example, its color. One such need is found in the 
casino environment where a dealer has a tray with a plurality of columns 
in each of which columns a number of chips of the same monetary equivalent 
designation are to be stacked. For example, one type of tray may have a 
plurality of columns and chip denominations of $1, $5, $10, $25, etc. are 
stacked in the respective columns. Each denomination of chip has a 
particular identification characteristic, such as color. 
For control and accounting purposes the supervisor of a group of locations, 
such as a number of card and/or dice tables, visually monitors the tray or 
trays at each location to determine the conduct of the play, the amount of 
money being wagered and to try to ascertain if the `house` is winning or 
losing. A need exists to provide more accurate information for this 
purpose. Also, the casino would like to have instantaneous information for 
all of the tables as to how play is progressing, the amount of money being 
wagered, the efficiency of a particular dealer and for other reasons. 
Therefore, it becomes desirable to be able to count the number of chips in 
each tray on an automatic basis. 
U.S. Pat. No. 4,755,941 to Lorenzo Becchi discloses a type of casino play 
monitoring and accounting system in which trays at the table are monitored 
as well as using a keypad or keyboard to enter cash transactions of a 
customer purchasing chips. This system uses a tray having a plurality of 
LEDs along each column. Each LED is to detect the presence or absence of 
an individual chip in its tray column. Such a tray monitoring system has 
problems in that it is difficult to construct with the plurality of LEDs 
and the LEDs produce `cross-talk` in the data acquisition mode which can 
effect the accuracy of the system. Also, the tray monitoring approach used 
by this patent cannot identify the individual chips by any characteristic, 
such as color. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention relates to a system that can be used to count the 
number of objects in a stack, such as in each of the columns of a casino 
tray for chips, and also to identify the individual objects, such as 
chips, by their respective colors. In accordance with the invention each 
column of the tray has a narrow beam ultrasonic sensor. The overall 
distance of a tray column is known and the sensor measures the distance 
between it and the closest object (chip) in the stack. Since the thickness 
of the object is known, by subtracting the distance measured by the sensor 
from the overall column distance, the number of objects in the stack of a 
column can be computed. 
Each column of the tray is also provided with a sensor that can identify 
individual objects on the basis of one or color characteristics of the 
object. In one embodiment of the invention the ultrasonic sensor and color 
sensor are at one end of each tray channel and preferably integrated into 
a single package. This permits the identity of the object closest to the 
color sensor placed in a column to be determined on the basis of its color 
or individual objects to be so identified as they are placed in a column 
one at a time. 
In another embodiment, the color of the object for each column can be 
preset and if a dealer places the wrong color object in the column an 
alarm can be actuated. In still a further embodiment, a color sensor at 
one end of a tray column can be used to set the reference color of the 
column by the first object placed in the column and a color sensor at the 
other end used to sense each additional object placed in the column. A 
mis-match of the two colors actuates an alarm if the wrong type of object, 
as determined by its color, is being placed in the column. 
OBJECT OF THE INVENTION 
one object of the invention is to provide a system for counting the number 
of objects in a stack of objects and to identify such objects on the basis 
of a physical characteristic, such as color. 
A further object of the invention is to provide a tray for stacking 
objects, such as chips for a casino, having sensors to determine both the 
number of chips in a tray column and the identity of the chips by their 
color. 
Another object is to provide a tray for casino chips that uses an 
ultrasonic sensor to detect the number of chips in a tray column by 
measuring round trip transit time of ultrasonic energy reflected from a 
chip in the tray column and a color sensor for detecting the identity of 
the type of chip in the column. 
Still a further object is to provide a system for measuring the value of a 
plurality of casino chips in a column of a tray by measuring the round 
trip time of a pulse of transmitted ultrasonic energy reflected from the 
chips, determining the value of the chips on the basis of a color 
characteristic and calculating the value from this information.

DETAILED OF THE INVENTION 
A preferred embodiment of the invention is described with respect to a chip 
holding tray for use in a casino. Referring to FIG. 1, a tray 10 is shown 
having a plurality of columns 12, here illustratively shown as four, 
although a greater of lesser number can be used. Each column 12 is used to 
stack a plurality of objects, such as casino chips 14. Each of the chips 
is identified by a particular characteristic, such as a color. This is 
shown by the different types of cross-hatching for the chips of the 
different columns. Each color chip has a predetermined monetary value. 
In use, a tray 10 is usually mounted at a slight angle to the horizontal so 
that the chips 14 will accumulate in each column 12 against one end wall 
18, hereafter called a reference end R. At the opposite end wall, 
hereafter called the sensing end S, there is an ultrasonic sensor 20, to 
be described in detail below, in each of the columns 12. The physical 
length of each column 12 is known as is the thickness of each chip 14. The 
chip thickness is the same for all monetary values. 
Upon transmitting an ultrasonic signal from a transducer along the length 
of its respective column, it is reflected back to the transducer from the 
closest chip in the column. By measuring the round trip time of the 
ultrasonic signal, the number of chips in a respective column can be 
determined. This is a simple calculation to be performed by a 
microprocessor in terms of subtracting the round trip time of the 
reflected signal from the known round trip time of transmission of a 
signal corresponding to the full length of a column. The distance result 
is divided by the known thickness of a chip and this gives a count of the 
number of chips in a column. 
In a preferred embodiment of the invention, as described below, the sensors 
20 of the plurality of tray channels are energized simultaneously so that 
the count of all of the tray columns can be acquired at the same time and 
the monetary value for each channel calculated as desired, either 
simultaneously or in sequence. 
In addition to the chip count in each tray column 12 it is desired to 
calculate their monetary value. That is, the chip count is to be 
multiplied by the value of the chips in the column, for example, as 
determined by their color. A computer can process this data for use by the 
casino. 
In general, each dealer who is responsible for a tray, or trays, at a 
gaming table sorts the different value chips to his own liking. The dealer 
is usually only required to keep chips of only one value (color) in each 
tray column. In accordance with the invention, the tray 10 also has a 
color sensor 30, to be described below, in each column. By identifying the 
color of the chips in each of the columns, the monetary value of the chips 
can be calculated since chips of a particular color have a predetermined 
monetary value. Here also, the operation of the color sensors 30 can be 
multiplexed. It is preferred that each column 12 of a tray be checked in 
sequence with both the count sensor 20 and the color sensor 30 operation 
for one channel being completed before the next column is checked. 
FIG. 2 is a schematic block diagram of the system showing details of the 
ultrasonic sensor 20 and color sensor 30 for a single tray column. A 
microprocessor 40 of a suitable capacity that has been appropriately 
programmed controls the operation of the system. The microprocessor 40 
generates an appropriate signal at the start of a cycle for measuring the 
column to actuate a transmit driver circuit 42 for the ultrasonic sensor 
20. This produces a signal of the appropriate frequency, to be described 
below, that is applied through a transmit-receive switch 44 to the 
transducer (not shown), for example of the PZT piezoelectric type, of the 
ultrasonic sensor 20. The trigger signal from the microprocessor also 
triggers a counter 47 to start counting. Counter 47 can be, for example, a 
sixteen bit counter with a clock frequency of 50 Mhz. 
After the signal is transmitted by the sensor 20, the switch 44 changes to 
the receive mode under control of the microprocessor 40. The signal 
reflected back from the closest chip in the column, or from the column 
opposing wall R if the column is empty of chips, is applied to a video 
amplifier 46 and then to a video detector 48. The output of the video 
detector is applied to the counter 47 to stop the count. The accumulated 
count corresponds to the round trip time of the ultrasonic signal. That 
is, it is the measurement of the distance. The output count of counter 47 
is applied to microprocessor 40. The sensor 20 also preferably has a 
temperature sensor 22 that is applied to a temperature measuring circuit 
24 and the temperature data, which is in digital form, is also supplied to 
the microprocessor 40. The microprocessor 40 computes the round trip 
transit time of the signal transmitted from sensor 20 from the count of 
counter 47, as modified by the temperature sensed, and from this 
calculates the number of chips in the column. 
In a preferred embodiment of the invention the ultrasonic sensors 20 for 
all of the columns 12 of a tray 10 are operated at the same time. That is, 
each sensor 20 has its own switch 44, video amplifier 46, video detector 
48 and counter 47. The microprocessor 40 triggers the start of the 
measuring cycle for all of the sensors 20 of the tray at the same time. 
The data obtained from each sensor 20 during the measurement cycle is 
stored in its respective counter 47 and each of the counters is connected 
to the microprocessor 40 data input line. At a predetermined time the 
microprocessor 40 looks at the data of each counter 47 and processes it to 
produce output data. The counter 47 of the column is set to count to its 
maximum limit if no chips are present in a column of the tray. This avoids 
an overflow condition. 
Microprocessor 40 also controls a light generator and light field rotating 
logic circuit 50. As described in greater detail below, this provides the 
necessary signals that are transmitted through a set of amplifiers 52 to 
the color sensor 30 to enable it to sense the color of the chip. The color 
sensor 30 has detectors and the information sensed is applied through a 
set of amplifiers 54 to a color recognition and logic circuit 56 that 
identifies the sensed color of the chips in a channel and, consequently, 
their respective monetary values. This information also is applied to the 
microprocessor 40. Using the information returned from the two sensors 20 
and 30, the microprocessor 40, or another computer, can make a numerical 
value calculation of the value of the chips in a column. 
The color sensors 30 in the tray preferably are gated on sequentially to 
scan each tray column. This is done to economize on the color sensor 
electronics. Scanning is accomplished by providing a multiplexer (not 
shown). Of course, if desired, the color sensor electronics can be 
replicated and the color sensor data for each channel produced 
continuously. In this case the microprocessor 40 would scan the color 
sensing electronics for each channel to acquire the data and associate it 
with the chip count data for the channel. 
FIGS. 3A and 3B show a combined ultrasonic and color sensing detector 70. 
It should be understood that the combined sensor of these figures can be 
split into two parts. That is, the ultrasonic and color sensing portions 
each can be in separate housings, as shown in FIG. 1, and used at the same 
end wall of the tray. Sensor 70 has a housing 72 with a threaded end 74. 
At the other end of the housing is a piezoelectric element 23, such as of 
PZT, mounted to a front window 26 of the housing. The part of the front 
window 26 for the ultrasonic sensor can be, for example, of stainless 
steel or of MYLAR plastic. An impedance matching element (not shown) which 
can be, for example, of rubber, is used to match the impedance of the 
element 23 to the window 26 and to the air interface in front of the 
window. This reduces unwanted ringing. A cable 25 connects element 23 to 
the electronic circuit shown in FIG. 2. The temperature sensor 22 also is 
mounted to the front window 26 and preferably extends through the window 
to more accurately sense the temperature. 
The ultrasonic sensor element 23 receives energy from the driver circuit 42 
preferably at a frequency of at least about 250 KHz. This frequency 
provides a distance measuring resolution of about 0.02", which is about 
one-sixth the thickness of a standard casino chip. Making the frequency 
higher will increase the measuring resolution. A frequency of 500 KHz has 
been found to be satisfactory. Increasing the frequency to the range of 1 
Mhz-2 Mhz will increase the measurement precision. Also, it is preferred 
that the angle of the energy beam from sensor 20 be made as narrow as 
possible. This minimizes crosstalk between adjacent columns. 
The color sensor has a plurality of bundles 58 of optical fibers are 
located around the outer periphery of the housing 72. There can be a 
transparent front window for the bundles. The color sensor uses the 
bundles 58 in a manner to be color specific. That is, each bundle 58 has 
one or more optical fibers 58a that transmits white light and one or more 
fibers 58b used as color specific detectors. When used as a detector a 
fiber has a filter to pass light of a specific color corresponding to the 
color of one of the chips that is to be held in the tray. 
Since sensor 70 has a plurality of the fiber bundles 58, each one can be 
specific to a particular chip color. For example, if five different color 
chips are to be held by a tray, then each of the bundles 58 would have 
five different color detectors. Alternatively, each of the bundles can be 
color specific. There can be several bundles for each specific color which 
would preferably be spaced at different locations around the housing 
periphery. Also, there can be bundles which transmit only white light and 
bundles that have only color detectors. 
Operation of the color sensor portion of the combined sensor 70 is also 
controlled by the microprocessor 40. In a typical operation cycle of the 
color sensor of a tray column, the white light is pulsed or is 
continuously on. The light is reflected back from the chip 14 in the tray 
column 12 to the color detectors in the sensor fiber optic bundles. The 
amplitude of the output from the different color detectors will vary 
depending upon the color of the chip from which the light is reflected. 
This information is used by the color mapping circuit 56 to determine the 
color. All of the bundles 58 of a sensor 30 are operated at the same time 
or the bundles can be scanned sequentially, such as proceeding around the 
ring of bundles one at a time. As another alternative, the fiber detectors 
for each specific color can be scanned sequentially. Each of these 
alternatives can be programmed for operation by the microprocessor 40. 
In a further alternative, the color sensor for one column can be set to a 
specific color. An alarm is sounded if a chip of a different color is 
placed in the column. This type of operation also can be programmed into 
the microprocessor 40. 
Preferably, one tray column 12 at time is scanned for color information. 
The color recognition and mapping logic circuit 56 detects the color that 
corresponds to the light reflected from the chip in the column. This can 
be either the maximum or minimum amplitude signal from a particular color 
detector depending upon whether an additive or subtractive system is being 
used. 
During the scanning of a tray column 12 for chip color information, the 
ultrasonic sensor 20 is also operated to acquire the information relative 
to the chip count. Information of the chip count of a column and the value 
of the chips in the column on the basis of the color is collected in the 
microprocessor 40 and thereafter it is conveyed to a central computer (not 
shown) which accumulates data from one or more of the trays of the tables 
of the casino and performs the necessary accounting functions. 
While the invention has been described with respect to the particular 
application for counting chips in a tray, it has other applications. For 
example, in a warehouse application where objects such as containers of 
different colors are stacked, the system can be used to count and identify 
the model number of the objects by their color.