Multiple flash array

A multiple flash lamp array having an electrically conductive reflector unit positioned between the flash lamps and a circuit board. A radiation-actuated last-flash indicator switch is positioned on the circuit board behind the last lamp to be flashed and is connected between an electrical ground circuit run and another circuit run. An opening is provided through the reflector at the last-to-flash lamp, in alignment with the last-flash indicator switch, and the rear edge of the opening is shaped to contact the electrical ground circuit run adjacent to the last-flash indicator switch for electrically grounding the reflector.

CROSS-REFERENCES TO RELATED APPLICATIONS 
Ser. No. 655,005, filed Feb. 4, 1976, now abandoned James M. Hanson et al., 
"Photoflash Lamp Array Having Conductive Reflector," assigned the same as 
this invention. 
Ser. No. 702,663, filed July 6, 1976, Paul T. Cote, "Last Flash Indicator 
for Photoflash Array," assigned the same as this invention. 
BACKGROUND OF THE INVENTION 
The invention is in the field of multiple photoflash lamp arrays. 
U.S. Pat. No. 3,935,442 to Hanson describes a flash array of the 
"FlipFlash" type having a plurality of flash lamps connected to a circuit 
board having circuitry for sequentially flashing the lamps. A metal-coated 
plastic reflector unit, shaped to provide individual reflectors for the 
lamps, is positioned between the lamps and the circuit board, and a metal 
clip is clipped to the reflector and rests against an electrical ground 
area of the circuit board so as to electrically ground the reflector and 
thus increase the stray capacitance of the array's electrical ground to 
surrounding space, thereby reducing the possibility of accidental flashing 
of the lamps when electrostatically charged persons or objects touch the 
array. 
The above-referenced Hanson patent application discloses an alternative way 
of connecting the conductive reflector unit to electrical ground of the 
circuit board, comprising one or more openings through the rear of the 
reflector unit aligned with electrical ground pads of the circuit board 
and shaped to bring a metal coating on the front of the reflector unit 
against or near to the electrical ground pads. For the purpose of 
electrically grounding the reflector unit to the circuit board for 
dissipating any electrostatic charges applied to the array, the connection 
therebetween need not be a direct contact because electrostatic charges 
that are likely to cause accidental flashing of the lamps will be about a 
thousand volts or more (at low energy) and can arc across a short gap 
between electrical ground of the circuit board and the metal of the 
reflector unit. 
The above-referenced Cote patent application discloses a last-flash 
indicator arrangement comprising a radiation-actuated switch near the 
last-to-flash lamp and connected electrically across the input terminals 
of the array. When the last lamp flashes, the indicator switch changes the 
resistance across the array's input terminals and actuates a last-flash 
indicator in the camera. 
SUMMARY OF THE INVENTION 
Objects of the invention are to provide an improved construction of a 
FlipFlash type of flash array and to reduce its manufacturing cost. 
The invention comprises, briefly and in a preferred embodiment, a multiple 
flash lamp array having a plurality of flash lamps connected to a circuit 
board carrying circuitry for sequentially flashing the lamps. An 
electrically conductive reflector unit is positioned between the lamps and 
the circuit board, and may be made of plastic with a metal coating on its 
front and/or back surface. A radiation-actuated last-flash indicator 
switch is positioned on the circuit board behind the last lamp to be 
flashed and is connected electrically between circuit runs which are 
connected to connector terminals of the array, one of which is electrical 
ground for the array. An opening is provided through the reflector unit 
between the last-to-flash lamp and the last-flash indicator switch, and 
the rear edge of the opening is contoured to bring the metal coating of 
the reflector against or near to the electrical ground run adjacent to the 
last-flash indicator switch so as to electrically ground the reflector for 
electrostatic charges. The electrical ground run can be widened or shaped 
like a pad in the vicinity of the last-flash indicator switch to 
facilitate the grounding of the reflector. The rear edge of the reflector 
opening can be contoured in the form of a rearwardly extending tab, and 
the inside surface of the tab can be tapered to facilitate its becoming 
metallized when the front surface of the reflector is metal coated such as 
by a vapor deposition technique. For a dual array such as the FlipFlash 
type, similar arrangements of indicator switches, electrical ground 
circuit runs, and reflector openings can be provided behind the 
last-to-flash lamp of each of the two groups of lamps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A multiple flash lamp unit 17 of the planar array type and containing a 
plurality of electrically fired flash lamps is provided with a plug-in 
connector tab 18 at the lower end thereof, adapted to fit into a socket of 
a camera or flash adapter. The lamp array 17 is provided with a second 
plug-in connector tab 18' at the top end thereof, whereby the array 17 is 
adapted to be attached to the camera socket in either of two orientations, 
i.e., with either the tab 18 or the tab 18' plugged into the socket. The 
array 17 is provided with an upper group 21 of flash lamps 22, 23, 24, and 
25, and a lower group 26 of flash lamps 27, 28, 29, and 30, the lamps 
being arranged in a planar configuration. Reflectors 22', etc., are 
disposed behind the respective flash lamps, so that as each lamp is 
flashed, its light is projected forwardly of the array 17. The lamps are 
arranged and connected so that when the array is connected to a camera by 
the connector 18, only the upper group 21 of lamps will be flashed, and 
when the array is turned end for end and connected to the camera by the 
other connector 18', only the then upper group 26 of lamps will be 
flashed. By this arrangement, only lamps relatively far from the lens axis 
are flashable, thus reducing the undesirable red-eye effect. 
The construction of the array comprises front and back housing members 36 
and 37, which preferably are made of plastic and are provided with 
interlocking members 38 which can be molded integrally with the housing 
members and which lock the housing members together in final assembly to 
form a unitary flash array structure. FIG. 2 shows a pair of interlocking 
members 38a carried at the rear of the side of the front housing member 36 
interlocked with a pair of interlocking members 38b of the back housing 
member 37. In the preferred embodiment shown, the front housing member 36 
is a rectangular concavity and the back housing member 37 is substantially 
flat and includes integral extensions 39 and 39' at the ends thereof which 
partly surround and protect the connector tabs 18 and 18' and also 
function to facilitate mechanical attachment to the camera socket. 
Sandwiched between the front and back housing members 36 and 37, in the 
order named, are the flash lamps 22, etc., a unitary reflector unit 41, 
preferably plastic, coated on the front surface with a metal such as 
aluminum and shaped to provide the individual reflectors 22', etc., a 
printed circuit board 42 provided with integral connector tabs 18 and 18', 
and an indicia sheet 43 which may be provided with instructions, 
information, and other indicia such as flash indicators located behind the 
respective lamps. 
The indicia sheet 43 may be of paper or thin cardboard and provided with 
openings where the flash indicators are desired, and covered with flash 
indicator material, such as a sheet-like, heat-sensitive plastic material 
48, for example biaxially oriented polypropylene, which shrinks or melts 
when subjected to heat or radiant energy from an adjacent flashing lamp 
thus effectively changing the color of the openings in the indicia sheet 
43 and indicating which lamps have been flashed. Openings 51 are provided 
through the reflector unit 41 and the circuit board 42 to facilitate 
radiation from flashing lamps reaching and flash indicators. The rear 
housing member 37 is transparent (either of clear material or provided 
with window openings) to permit viewing of the indicia on the indicia 
sheet 43. The front housing member 36 is transparent at least in front of 
the lamps 22, etc., to permit light from flashing lamps to emerge 
frontwardly of the array, and may be tinted to alter the color of light 
from the flash lamps. 
The height and width of the rectangular array are substantially greater 
than its thickness, and the heights and widths of the reflector member 41 
and circuit board 42 are substantially the same as the interior height and 
width of the housing member 36 to facilitate holding the parts in place. 
The tab 18, which is integral with the circuit board 42, is provided with a 
pair of electrical terminals 31 and 32, and similarly the tab 18' is 
provided with a pair of terminals 31' and 32', for contacting terminals of 
a camera socket for applying firing voltage pulses to the array. Each tab 
is provided with a third terminal 33 and 33', respectively, which 
functions to electrically short the circuitry of the inactive lower group 
of lamps when the array is plugged into a socket. The terminals 31 and 31' 
are shown as having a lateral "T-bar" configuration for temporarily 
shorting the socket terminals while the array is being plugged in, to 
discharge any residual voltage charge in the firing pulse source and also 
to reduce the likelihood of lamps being accidentally flashed by 
electrostatic voltage when the array is handled. The latter is achieved 
because the "T-bar" terminal is more readily touched than the other 
terminals by an electrostatically charged person, and, being connected to 
the large-area electrical ground circuitry, the charge tends to become 
dissipated into surrounding space instead of passing through the primers 
of the flash lamps. 
The circuit board 42 has a "printed circuit" thereon, as will be described, 
for causing sequential flashing of the lamps by firing voltage pulses 
applied to the terminals 31, 32 or 31', 32'. The top and bottom halves of 
the printed circuitry preferably are reverse mirror images of each other. 
The lead wires 22a, 22b, etc., of the lamps 22, etc., may be attached to 
the circuit board 42 in various ways, such as by means of metal eyelets 
22a', 22b', etc., placed through openings in the board. The lead wires 
22a, 22b, etc., pass through openings 52 in the reflector member 41 and 
into or through the respective pairs of eyelets 22a', 22b', etc., and the 
ends of the eyelets are crimped or bent to hold the lead wires and make 
electrical contact thereto and also to hold the eyelets in place with 
their heads in electrical contact with the circuit of the circuit board. 
Areas 59 on the transparent front housing member 36 may be made opaque or 
partly opaque, such as by making the surface roughened at these areas, to 
fully or partly conceal the lamp lead-in wires 22a, 22b, etc. and/or the 
lower portions of the lamps, for improved appearance of the array. 
The circuit board terminal 32 is part of a conductor run that is 
electrically connected to lead-in wire 24a of lamp 24 at the eyelet 24a' 
and terminates at radiation switches 61, 62, and 63 respectively 
positioned near lamps 24, 25, and 23. A circuit board conductor run 64 is 
connected electrically to the remaining lead wire of flash lamp 25 at 
eyelet 25a' and terminates at the radiation switch 61. A circuit board 
conductor run 65 is connected to the remaining lead-in wire of flash lamp 
23 at eyelet 23a' and terminates at the radiation switch 62. Similarly, a 
circuit board conductor run 66 is connected to the remaining lead-in wire 
of flash lamp 22 at eyelet 22b' and terminates at radiation switch 63. 
The radiation switches 61, 62, and 63 are respectively in contact with and 
bridge across the circuit runs that are connected to them. The material 
for the radiation switches may be suitable material initially having an 
open circuit or high resistance, the resistance thereof becoming zero or a 
low value when the material receives radiation in the form of heat and/or 
light from a respective adjacent lamp, upon the lamp being flashed. For 
this purpose, each of the radiation switches is respectively positioned 
behind and near to a flash lamp 24, 25, 23. Windows in the form of 
transparent sections or openings 69 may be provided in the reflectors in 
front of the switches as shown in FIG. 3 to facilitate radiation transfer. 
A suitable material for the radiation switches is disclosed in U.S. Pat. 
No. 3,951,582 to Holub et al. Each of these radiation switches, upon 
receiving heat and/or light radiation from the adjacent lamp when it is 
flashed, changes from an open circuit or high resistance to a closed 
circuit or low resistance between its switch terminals on the circuit 
board. 
As has been explained, the lower portion of the circuit board contains a 
substantially reverse mirror image of the same circuit shown in the upper 
part of the circuit board, and therefore will not be described in detail. 
It will be noted that the circuit runs from the plugged-in terminals 31 
and 32 at the lower part of the circuit board extend upwardly so as to 
activate the circuitry in the upper half of the circuit board. Similarly, 
when the unit is turned around and tab 18' is plugged into a socket, the 
circuit board terminals 31' and 32' will be connected to and activate the 
lamps which then will be in the upper half of the circuit board, and hence 
in the upper half of the flash unit 17. This accomplishes, as has been 
stated, the desirable characteristic whereby only the group of lamps 
relatively farthest away from the lens axis will be flashed, thereby 
reducing or eliminating the undesirable red-eye effect. 
The circuit on the circuit board 42 functions as follows. Assuming that 
none of the four lamps in the upper half of the unit 17 have been flashed, 
upon occurrence of a first firing pulse applied across the terminals 31, 
32, this pulse will be directly applied to the lead-in wires of the 
first-connected flash lamp 24, whereupon the lamp 24 flashes and becomes 
an open circuit between its lead-in wires. Heat and/or light radiation 
from the flashing first lamp 24 causes the adjacent radiation switch 61 to 
become a closed circuit (or a low value of resistance), thereby connecting 
the circuit board terminal 32 electrically to the lead-in wire of the 
second lamp 25 at eyelet 25a'. By the time this occurs, the firing pulse 
has diminished to a value insufficient to cause the second lamp 25 to 
flash. When the next firing pulse occurs, it is applied to the lead-in 
wires of the second lamp 25, via the now closed radiation switch 61, 
whereupon the second lamp 25 flashes, thereby causing radiation switch 62 
to assume zero or low resistance, and the second lamp 25 now has an open 
circuit or high resistance between its lead-in wires. When the next firing 
pulse occurs, it is applied via now closed radiation switch 62 to the 
third lamp 23, thereby firing the lamp which becomes an open circuit, and 
the radiation from it causes the radiation switch 63 to become essentially 
a closed circuit across its terminals. Thus, the next firing pulse will be 
applied, via now closed radiation switch 63, to the lead-in wires of the 
fourth flash lamp 22, thereupon causing the lamp to flash. Since this lamp 
is the last lamp in the active circuit, it does not matter whether its 
lead-in wires are an open or closed circuit after flashing. Additional 
flash lamps, radiation switches, and electrical conductors can be 
employed, if desired, using the just described principles. When the flash 
unit is turned around the other connector tab 18' attached to the camera 
socket, the group of lamps that then become uppermost and relatively 
farthest away from the lens axis will be in an active circuit and will be 
flashed in the same manner as has been described. In a preferred 
embodiment, the lamps 22, etc., are high voltage types, requiring up to 
2000 volts for example, at low current, for flashing, and they can be 
fired by impacting or stressing a piezoelectric element in the camera. 
Last-flash indicator radiation switches 70 and 70' are provided on the 
circuit board 42 respectively behind the last-to-flash lamps 22 and 30 of 
each of the groups 21 and 26 of lamps. Openings 71 and 71' are 
respectively provided in the reflectors 22' and 30' between the lamps 22 
and 30 and switches 70 and 70' to facilitate radiation from the lamps when 
flashed reaching the switches. The last-flash indicator switches 70 and 
70' can be the same material, and may also be approximately the same size 
and shape, as the flash-sequencing switches 61, etc. The circuit runs are 
shaped so that the last-flash indicator switch 70 bridges across and 
between the circuit run 72 which terminates at the connector terminals 32 
and 33', and the common electrical ground circuit run 58 which terminates 
at the connector termainals 31 and 31', so that when this switch assumes a 
low or zero value of resistance in response to the flashing of the last 
lamp 22, it will actuate the last-flash indicator circuit in the camera 
via its electrical connection thereto through the connector terminals 31 
and 32 which have previously functioned to connect firing pulses to the 
flash lamps. Similarly, the last-flash indicator switch 70' behind the 
other last-to-flash lamp 30 bridges across and between the common ground 
circuit run 58 and the circuit run 72' which terminates at the connector 
terminals 33 and 32', so that when the connector 18' is plugged into the 
camera the switch 70' will function as has been described for switch 70. 
One or both of the openings 71 and 71' through the reflector unit 41 are 
shaped and contoured so as to bring the metal coating on the front of the 
reflector unit near to or in contact with a portion of the electrical 
ground circuit run 58, adjacent to the respective last-flash indicator 
switch 70 and/or 70', for example as shown in FIG. 4. In the embodiment of 
FIG. 4, the rear edge of the opening 71 (and/or the opening 71') is 
contoured to provide a tab 73 extending rearwardly from the reflector unit 
and positioned to extend against or adjacent to the electrical ground run 
58 near the last-flash indicator switch 70 (and/or switch 70'). The metal 
coating on the front surface of the reflector unit extends rearwardly on 
the inner surface (toward the opening 71) of the tab 73 so as to be 
brought near to or against the electrical ground circuit run 58. The inner 
surface of the tab 73 may be tapered or sloped inwardly toward the 
radiation switch as shown to facilitate the metal coating being applied 
thereon when the front surface of the reflector unit is metallized, such 
as by a metal vapor deposition coating process. The electrical ground 
circuit run 58 may be widened or otherwise shaped to form an electrical 
ground pad area 76 adjacent to the last-flash indicator switch 70 (and/or 
70'). 
The openings 71 and 71' perform dual functions of facilitating radiation 
from the last-to-flash lamps 22 and 30 reaching the last-flash indicator 
switches 70 and 70', and by their rear edge contour, such as the tabs 73, 
extending to an electrical ground run of the circuitry, they effectively 
electrically ground the reflector unit so that any electrostatic charges 
applied to the circuitry or array by a charged person or object are 
dissipated into surrounding space without going through any lamp primers, 
thereby reducing the possiblity of accidental flashing of lamps by the 
electrostatic charge. Thus, an electrostatic charge applied to the "T-bar" 
terminals 31, 31' will become dissipated via the large areas of the 
circuitry ground and the reflector unit, and an electrostatic charge 
applied to the plastic housing 36 will become dissipated via the large 
areas of the reflector unit and the circuitry ground. The metal coating of 
the front surface of the reflector unit can be brought, by means of the 
tabs 73, into contact with the electrical ground run of the circuit board, 
or sufficiently near thereto so that electrostatic charges of sufficient 
voltage to cause lamps to flash (about 1000 volts or more, for example) 
will arc between the electrical ground run and the reflector unit's 
conductive surface and become dissipated into surrounding space. The tab 
73 further functions as a spacer to prevent the reflector metal coating at 
the remaining portion of the rear edges of the openings 71 and 71' from 
short-circuiting the switches 70 and 70' and the adjacent circuit runs, 
and also prevents flash lamp firing pulses from arcing from these switches 
and adjacent circuit runs to the conductive coating on the reflector unit, 
thus preventing malfunctioning of the array. 
The inventive concept of contouring the rear edge of a reflector opening 
for contacting a circuit conductor adjacent to a radiation switch, can be 
embodied with various types of conductive reflector construction, such as 
an all-metal reflector unit, and a reflector unit of electrically 
insulative material coated with metal or other electrically conductive 
material on the front and/or rear surfaces thereof. These various types of 
construction are contemplated by the terminology "conductive reflector" in 
the claims. 
While preferred embodiments of the invention have been shown and described, 
various other embodiments and modifications thereof will become apparent 
to persons skilled in the art, and will fall within the scope of the 
invention as defined in the following claims.