time delay neural network Alex Waibel backpropagation backpropagation Yann LeCun recognize handwritten ZIP codes max-pooling 3D object recognition Yann LeCun weight
The time delay neural network (TDNN) of Alex Waibel (1987) combined convolutions and weight sharing and backpropagation.  In 1988, Wei Zhang et al. applied backpropagation to a CNN (a simplified Neocognitron with convolutional interconnections between the image feature layers and the last fully connected layer) for alphabet recognition. In 1989, Yann LeCun et al. trained a CNN to recognize handwritten ZIP codes on mail. 
In 1992, max-pooling for CNNs was introduced by Juan Weng et al. to help with least-shift invariance and tolerance to deformation to aid 3D object recognition. 
LeNet-5 (1998), a 7-level CNN by Yann LeCun et al., that classifies digits, was applied by several banks to recognize hand-written numbers on checks digitized in 32x32 pixel images.
