The present invention relates to an electronic ladle weighing display device in overhead
cranes.
More particularly, the invention is concerned about display system having less number of
components, less weight and less maintenance requirement.
BACKGROUND OF THE INVENTION
Pressductor based electronics ladle weight display system is being used for crane ladle. The
system consisted of 4 no. pressductor load cell duly AC excited with 2A constant current with
ac mV output of load cell is processed Part-I as shown in figure 1. (Fig. 1.prior art) Then in
Part-ll the signal goes through DS-8 digital electronic panel which was a sophisticated
electronic system with programmable chips and microprocessor based controlling,
monitoring, data acquisition arrangement having RAM, ROM for process application. It was
having the mother board having 32 slots for 16 nos. of cards with individual address card
slots in DS-8 BUS in the form of PCB. As shown in figures 3 and 3(A) (prior art), the BUS
system was having Data bus, Address bus, Control Signal, Interrupt Signal, Analog bus with
initializing and blocking signals with LED indication. All PCB in the DS-8 system were
connected to the mother board with PCBs at the back. DS-8 cubical was housed with power
supply unit. Of +5 volt, + 15 volt, +24 volt and 48 volt AC for providing AC or DC supply. As
shown in figure 2 (prior art), DS- System was also equipped with Controls with and
memories as shown in figure 4 (prior art), Communication units as shown in figures 5, 6 and
7. (prior art), Analog l/P output unit, Digital l/P and O/P unit, Panel communication unit and
Load cell excitation and control unit. After DS-Panel, the digital output was taken to driver
unit then to 5 nos. of 24V seven segment large lamp display.
As shown in figures 1 to 10 (prior art), all the units in DS-8 panel, driver unit, large 24v lamp
display units were bulky and heavy requiring more manpower to handle and troubleshoot the
faults. Multi slot mother boards for 16 cards and 16 address boards generated a lot of loose
connection problem due to crane vibration and shock hazards. With the removal of PCBs
and address boards and refixing them back induced more loose connection problems in the
slots of the mother boards itself. As system was remaining on for 24 hours, the 24V lamps
were getting fused frequently posing problem for replacement lamps in Large Display Units.
The spares became obsolete and the defects were beyond repair in majority of the cards
and sections of the systems. Virtually the system could not give trouble free service in the
cranes because of regular wear and tear and dusty environment. There was increase in
customer complaints on weight display with system stability and repeatability. The ladle
weight display in overhead cranes was required for metallurgical parameter control during
steel preparation in LD convenors and also while taking hot metal from mixer.
CN 201201854 document entitled "Electronic scale for gantry crane" teaches a weighting
device for heavy gantry crane, in particular to an electronic scale for gantry cranes, which is
characterized by comprising an upper pin, an upper couple, a tension sensor, a lower
couple, a lower pin and a digit weight display instrument, wherein the upper couple is hinged
with the prior steel wire fixing bracket of a crane via the upper pin, the lower end of the upper
couple is fixedly connected with the upper end of the tension sensor, the lower end of the
tension sensor is fixedly connected with the upper end of the lower couple which is hinged
with a weight steel wire connector via the lower pin, the signal output of the tension sensor is
connected with the signal input of the digital weight display instrument via a signal line. The
electronic scale can display the prior hoisting weight in hoisting, to avoid overload. The
electronic scale has simple structure, high safety, low cost, practicality and simple
installment.
DE 3629158 document entitled "Electromechanical, transportable crane scale with electronic
digital display" teaches an electromechanical, transportable crane scale with electronic
digital display, in which an electromechanical load-sensing device operating on the
extension principle is located in a frame or housing between the crane hoist and the crane
hook. This load-sensing device is connected to an electronic circuit for assessing and digital
display of the weight of the load on the crane hook. The crane scale features at least two
load cells arranged symmetrically to the axis of the crane hoist on a base plate friction-
locked and perpendicular to the crane hoist, whose opposing faces each abut on a
connecting piece between two hoist cheekpieces, which extend to the level of the base
plate, and between which the bearing for the swivelling crane hook is located.
Frequent replacement of 24V, 5 watt bulbs of large display unit which are kept on for 3 shift
operation and regular customer complaint on confusing segment / digit indication with bulky
driver unit, power supply unit prompted the inventors to develop the present invention Thus
the inventors proposed the present invention to overcome the problems in the prior art. It
would overcome the difficulties with optimum available resources and provide trouble free
service for process improvement and customer's satisfaction.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the problems/disadvantages of the prior
art.
Another object of the present invention is to provide an electronic ladle weighing display
device in overhead cranes with less number of components.
Another object of the present invention is to decrease the weight of the display device.
Another object of the present invention is to make the display device cost effective.
Another object of the present invention is to provide a device with simple trouble shooting
techniques.
Yet, another object of the present invention is to provide a device with power saving and
energy conservation.
SUMMARY OF THE INVENTION
According to one aspect of the present invention , it provides an electronic ladle weighing
display device in overhead cranes comprising:
a housing;
a pair of PCB;
power supply units;
plurality of display units comprising of local display units with large display units wherein
said display units comprises seven segments developed with LEDs;
driver circuit is being adapted to drive plurality of said large display units;
Excitation unit is being used to get AC Load Cell signal output for further processing and
amplification to DC and signal level improvement.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 illustrates electronic circuit of ladle weighing display system present in the prior art.
Fig 2 illustrates, ladle weighing display system present in the prior art.
Fig 3 illustrates address coding board for I/O unit present in the prior art.
Fig 3A illustrates Mother Board for electronic cards with slots in the prior art.
Fig 4 illustrates block diagram of ladle weighing display system present in the prior art.
Fig 5 illustrates central processor unit in the form of a microcomputer present in the prior art.
Fig 6 illustrates digital input board for reading in digital signal states from process
transducers present in the prior art.
Fig 7 illustrates series connection and termination of buses in different racks present in the
prior art.

Fig 8 illustrates Example of System Blocks diagrams with Connectors for one card in the
prior art.
Fig 9 illustrates rack with printed circuit boards present in the prior art.
Fig 10 illustrates Complicated PCB laid outs of Mother Board in the prior art.
Fig 11 illustrates ladle weighing display system in overhead cranes of the present invention.
Fig 12 illustrates electronic ladle weighing display system A/D converter, decoder and driver
for overhead cranes of the present invention.
Fig 13 illustrates transformer for ladle weighing display system in overhead cranes of the
present invention.
Fig 14 illustrates power supply of ladle weighing display system in overhead cranes of the
present invention.
Fig 15 illustrates junction box for ladle weighing display system in overhead cranes of the
present invention.
Fig 16 illustrates digital weight indicator for ladle weighing display system in overhead
cranes of the present invention.
Fig 17 illustrates Dimension details of the different Housings of ladle weighing display
system in overhead cranes of the present invention.
Fig 18 illustrates remote large LED display of ladle weighing display system in overhead
cranes of the present invention.
Fig 19 illustrates a schematic diagram of electronic ladle weighing display system of the
present invention and the prior art.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
According to the invention there is provision of an electronic ladle weighing display system in
overhead cranes comprising four number of pressductor type load cells duly AC excited and
analog signal processed part (I) as shown in figure 11, in Part (II) with non-customary
circuit components. Analog output is converted to digital form through AD converter (1) and
then multiplexed to give BCD output (2) which is decoded and fed to IC ULN 2003 (3) based
driver circuit to drive five nos. of Large 7 segment LED display units (5) as shown in figure
12.
There are three number of DC power supply circuits (4) used for the Crane Weighing Display
unit. They are ± 5 V and + 24 V. These are designed with normal Diodes, Bridge Rectifiers
and Capacitors. ± 5 V is required for the converter circuit, Analog Circuit Amplifier and
Buffers.
+ 24 V is used for driving the Large LED Display units (5). The current consumption of this
power supply circuit (4) is less than 0.5 Amps because of use of multiplexed LED based
Digit Display (5) glowing system as shown in figure 14.
The pressductor load cell output in the range of 70 to 600 mV, AC 50 HZ at full load is
processed and amplified with load cell amplifier circuit having IC-1, IC-II & IC-III (OP-07) and
the field effect transistors 2N3819 (T1 & T2) and transistors BC177 (T3 & T4) receiving the
10V synchronizing signal from the Excitation unit and it converts the input AC mV signal to
DC. The IC1 receives the summing signal as input after rectification and amplification. The
Capacitors C1, C2 & C5 are used as low pass filters which reduces the AC components and
noises. IC II & IC III Amplifiers are for Tare and Gain circuit. Maximum 2.0 V output is taken
with input of 600 AC mV signal which is fed for A/D Conversion. The output is linear to the
load cell output signal which is linear to the load exerted through the pressductor load cells.
The signal is fed to the Amplifier and AD card. The AD converter (IC-7135) (1) is a versatile
single chip integrated circuit having 28 pin DIP, multiplexed digital output with polarity
indication, over range, under range facilities. It works with an external clock of 120 KHZ.
Accuracy range is better with capability to drive 41/2 7 segment display with maximum
input to the circuit is 2V DC and the output is 4 1/2 digit Multiplexed BCD (2).
The IC-7448 is a BCD (2) to 7 segment decoder (7) which decodes the analogue output to
digital 4 bit BCD input data for 7 segment output which can be used for other logic circuits
rather than the directly driving the display. The logic developed further drives the large
current transistors through the driver transistor array ULN 2003 (3) and power transistors
2N6105.
Two displays are developed one for local display (6) and other is displayed at the remote
place. The local display (6) consists of 4 nos. of 7 segment LED display LT542 which are
connected in parallel to the large displays. These are mounted on the front portion of the
weighing panel.
The seven segment LED display with each segment having 50 LEDs and 5 nos. of displays
which are located in a remote place of 5 meter distance from the main weighing panel. Each
display is wired as a common anode display and each segment is connected parallel to the
junction box which function drives the display like multiple common anode display as shown
in figure 18.
Finally the system designing and implementation was taken up for Part-ll i.e. 16 cards with
16 address cards, with multi slot mother board and driver unit and 24v large lamp display
units were replaced with 5 nos. of seven segment LED Large display units (5) and made
system workable with small driver card made of IC ULN 2003 (3) based circuit as shown in
figures 11,12,13,14 and 18. The complete system setup is reduced to two intermediate
PCBs designed and prepared with electronic components locally available.
Illustration of the best workable Embodiment of the Invention
The best workable embodiment of the invention is the display system where the complete
display system is carried out with less consumption of cable for the Large display units. The
total circuitry component is very less comparing to the earlier system. LED system is having
long life, better illumination and less maintenance requirement.
ADVANTAGES OF THE INVENTION
1. User Friendly
2. Customer can go for quality productivity
3. Auto zero facilities when input zero.
4. Better accuracy and system repeatability.
5. Easily replaceable.
6. Better power saving.
7. The system is less in weight, size and handy as shown in figures 15,16 and 17.
8. Cost is much less than the earlier system.
9. No maintenance is required for months together.
10. Fault diagnosis and troubleshooting become simpler.
The invention has been described in a preferred form only and many variations may be
made in the invention which will still be comprised within its spirit. The invention is not limited
to the details cited above. The PCBs, LEDs, load cells, diodes, bridge rectifiers, capacitors,
decoders, and display units as stated do not limit the scope of the present invention. The
structure thus conceived is susceptible of numerous modifications and variations, all the
details may furthermore be replaced with elements having technical equivalence. In practice
the materials and dimensions may be any according to the requirements, which will still be
comprised within its true spirit.
We Claim
1. An electronic ladle weighing display device in overhead cranes comprising:
a housing;
a pair of PCB;
power supply units;
plurality of display units comprising
plurality of local display units with plurality of Large display units wherein said display
units comprises seven segments developed with LEDs;
driver unit being adapted to drive plurality of said large display units;
Excitation Unit is being used to get AC Load Cell signal output for further processing
and amplification to DC and signal level improvement.
2. Device as claimed in claim 1, wherein said local display unit comprises at least four
seven segment LEDs being connected in parallel to said large display units.
3. Device as claimed in claims 1 to 2, wherein said large display units comprises at
least five seven segment LEDs being located in a remote distance from the weighing
panel.
4. Device as claimed in claims 1 to 3, wherein said each display unit is wired.
5. Device as claimed in claim 1, wherein said each segment comprises at least 50
LEDs.
6. Device as claimed in claim 1, wherein said power supply units are Direct Current
(DC).
7. Device optionally comprises 4 ½ digit AD conversion.
8. Device optionally comprises a provision of remote display units with local display
units.
9. An electronic ladle weighing display device in overhead cranes as herein
substantially described and illustrated with the accompanying drawings.

The present invention relates to an electronic ladle weighing display device in
overhead cranes. It comprises a housing, a pair of PCB, power supply units (4),
plurality of display units comprises plurality of local display units (6) with plurality of
Large display units (5). The display units comprise seven segments developed with
LEDs, driver unit is adapted to drive plurality of the large display units (5). The
Excitation Unit is being used to get AC Load Cell signal output for further processing
and amplification to DC and signal level improvement.