We present the results of UBVJHKLM photometry of R CrB spanning the period from 1976 to 2001 .
Studies of the optical light curve have shown no evidence of any stable harmonics in the variations of the stellar emission .
In the L band we found semi-regular oscillations with the two main periods of \sim 3.3 yr and \sim 11.9 yr and the full amplitude of \sim 0 \aas@@fstack { m } 8 and \sim 0 \aas@@fstack { m } 6 , respectively .
The colors of the warm dust shell ( resolved by Ohnaka et al . [ 2001 ] ) are found to be remarkably stable in contrast to its brightness .
This indicates that the inner radius is a constant , time-independent characteristic of the dust shell .
The observed behavior of the IR light curve is mainly caused by the variation of the optical thickness of the dust shell within the interval \tau ( V ) = 0.2 - 0.4 .
Anticorrelated changes of the optical brightness ( in particular with P \approx 3.3 yr ) have not been found .
Their absence suggests that the stellar wind of R CrB deviates from spherical symmetry .
The light curves suggest that the stellar wind is variable .
The variability of the stellar wind and the creation of dust clouds may be caused by some kind of activity on the stellar surface .
With some time lag , periods of increased mass-loss cause an increase in the dust formation rate at the inner boundary of the extended dust shell and an increase in its IR brightness .
We have derived the following parameters of the dust shell ( at mean brightness ) by radiative transfer modeling : inner dust shell radius r _ { in } \approx 110 R _ { * } , temperature T _ { dust } ( r _ { in } ) \approx 860 K , dust density \rho _ { dust } ( r _ { in } ) \approx 1.1 \times 10 ^ { -20 } { g cm ^ { -3 } } , optical depth \tau ( V ) \approx 0.32 at 0.55 \mu m , mean dust formation rate \dot { M } _ { dust } \approx 3.1 \times 10 ^ { -9 } { M _ { \sun } yr ^ { -1 } } , mass-loss rate \dot { M } _ { gas } \approx 2.1 \times 10 ^ { -7 } { M _ { \sun } yr ^ { -1 } } , size of the amorphous carbon grains \la 0.01 \mu m , and B - V \approx - 0.28 .