🚀 go-pugleaf

I just bought a cheap quartz clock with an LCD.  It is one of those
smallish units that you can stick on your refrigerator, desk, or
whatever, and has mode/set buttons.  I have had similar clocks
before - in  a different package - so I assume the internals are
all the same.  I know little of electronics, so here goes the description
of my problem as far as I can see it. 

The clock works fine except that, whenever I place it in direct sunlight
it turns itself off.  I.e. it is not that the display goes blank, but
the clock resets itself too.  This seems equivalent to what happens if
I take the battery off.
The behaviour is reproduceable and it does the same thing
when close to an incandescend (sp?) light bulb.  The battery seems
fine, I had it checked out.  I took the clock appart and it there seems
to be nothing loose.  There is a single board with contacts for the set/mode
buttons, something that has to be the quartz what-ever, and contacts leading
to the upper side of the board, where there is a connecting white plastic bar,
with some black (i guess conducting) inserts going to what seem to be the
"in" contacts in the LCD.  The reaction to the sunlight is pretty fast,
and somewhat cumulative: it takes ~3 secs at the beginning, and later it
can be on 1 sec or less.

Since I wanted the clock to place on the stem of my bicycle, removing
it from direct sunlight is not a solution :-).  Besides, I am pretty curious.

suggestions?-	thanks-
	eduardo

p.s. Sorry for the length of this.