Data processing: generic control systems or specific application – Specific application – apparatus or process – Article handling
Reexamination Certificate
2000-11-27
2004-08-17
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Article handling
C700S095000
Reexamination Certificate
active
06778878
ABSTRACT:
TECHNICAL FIELD
This invention relates to monitoring component holders on a component placement machine.
BACKGROUND
Component placement is one of the most labor and data intensive operations in electronic board assembly. Current high-speed component placement equipment can place up to 10,000 to 30,000 components per hour, depending on configuration, and can carry up to 1,000,000 or more individual components.
Surface mount components are typically supplied by component vendors as rolled tapes of components that must be loaded onto individual feeders, sometimes called component dispensing cartridges, that can then be mounted in corresponding feeder slots on the machine. These rolls of components (up to, in some cases, 10,000 or more components per roll) may be loaded onto the feeders either at a stock room or at the machine, and the loaded feeders then loaded into feeder slots. Some components are supplied in tubes or in trays rather than on rolled tape, and must also be placed in a specified location on the machine for picking. As used herein, the term “component holder” is intended to encompass rolled component tape feeders, component tube holders, component bins, and other types of devices for holding a quantity of components for picking. The term “component holder receptacle” means a space on a placement machine for receiving any one of a number of holders, such as a feeder slot.
Component placement machines can have many component holder receptacles (e.g., 150 or more), each accessible by a placement turret or other picking mechanism that picks individual components from the holders in the receptacles and places them in particular locations on a printed circuit board, according to programmed instructions. For application flexibility, each holder and receptacle is generally constructed to be compatible with many different components.
Two classes of placement machines are currently available in the surface mounted component placement equipment market. The turret type of placement machine has a rotating turret on which 10-20 placement heads are mounted. The turret rotates about a fixed vertical axis. The printed circuit board is mounted on a moving table on one side of the turret, and there is a moving bank of feeders on the opposite side of the turret. The turret picks components from the feeders on one side, while placing previously picked components on the other side of the turret. In the gantry type of machine, the printed circuit board and the feeders remain stationary during the placement process, and a pick mechanism is moved on an overhead gantry system. The pick mechanism moves between different feeders to pick up components and then place them onto the printed circuit board. Multi-head gantry systems employ ten to twenty gantry pick mechanisms ‘ganged’ together to increase the throughput of the machine.
Some prior art attempts to catch assembly errors on gantry-type machines featured manual scanning by the operator. Scannable bar code labels are placed near each slot on the machine. After selecting the machine placement program and loading the program into the system, and just before putting a feeder onto the placement machine, the operator would scan the component part number from the reel in the feeder and then scan the slot number on the placement machine where the feeder was to be located. The system would compare the part number and slot number with the part numbers and slot numbers in the program, and alert the operator if the scanned information did not match the program. If no error was detected, the operator would be prompted to place the feeder onto the placement machine in the scanned slot. Hopefully, the operator would place the feeder in the same slot as scanned.
To improve on the system with manual scanning of part number and slot number, some systems eliminate scanning of the slot number by incorporating a sensor on the slot to sense the presence and absence of a feeder. Just before putting a feeder onto the placement machine, the operator scans the component part number from the reel in the feeder. Then, within a predetermined period of time (e.g., 20 seconds), the operator must place the feeder onto the placement machine. The sensor triggered by the feeder identifies the slot number on which the feeder is placed. If the slot number and part number pair does not match the slot number and part number pair in the placement program, an alarm sounds. All verification is done right next to the machine, with production stopped while the feeders are individually loaded and verified during setup.
In what is sometimes referred to as the “smart feeder” approach, each feeder is embedded with an erasable, programmable read-only memory (EPROM). As the operator loads a component reel into a feeder, he loads the component's part number (hopefully, matching the part number of the components just loaded onto the feeder) into the feeder's EPROM. The placement machine is built with EPROM readers integrated into each slot. When the feeder is placed into a slot, the machine reads the part number in the EPROM. Since the placement machine knows the slot number location of each part number, the placement program is no longer driven by slot number but is driven by part number. For example, part number “12345” can be placed in any slot on the placement machine and the placement machine will go to the correct slot to pick a component with part number “12345”. If a different component is to be loaded onto the feeder, the feeder EPROM must be reprogrammed.
The physical arrangement of components, feeders and slots must be in accordance with the expected arrangement as programmed in the machine. Any error in the arrangement can cause a corresponding error in the placement of components on the board. In a high volume, low mix manufacturing environment, a component loading error can produce a high number of defective printed circuit boards in a short period of time. In a low volume, high mix environment the chance of component loading error increases because of frequent feeder manipulation for product change over. If a wrong component is loaded onto the feeder, or the feeder is placed into a wrong slot on the machine, an assembly error is introduced. Because a placement machine can assemble thousands of printed circuit boards in a short time period, an assembly error due to wrong component placement can quickly cause major losses of time and money.
SUMMARY
The invention features a system for guarding against some of the typical loading errors that can occur even with the most conscientious machine operators, as well as providing much-needed inventory and maintenance data.
According to one aspect of the invention, an improvement is provided in a machine for placing electronic components on a printed circuit board. The machine has a series of electronic component holder receptacles for storing electronic components, and a movable pick head for picking selected components in a programmed sequence from component holders placed in the holder receptacles, and placing the picked components in designated locations on a circuit board. In my improvement, the component holder receptacles each have an associated, adjacent key receptacle for receiving a machine-readable holder identification key attached to a component holder to be loaded into the key receptacle after the component holder is loaded into the holder receptacle. The machine also has a controller constructed to identify, from identification keys inserted into the identification key receptacles, the loaded component holders to which the keys are attached.
In some embodiments, the identification keys each include a programmable memory containing holder-specific data, such as remaining component inventory.
In a preferred embodiment, the key receptacles of the component holder receptacles are connected serially, for communicating with the controller over a common data path. The key receptacles of the component holder receptacles each sequentially increment and relay downstream a communication received from the controller, and
Accu-Assembly Incorporated
Fish & Richardson P.C.
Picard Leo
Rapp Chad
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