What is that?
And mbarazeen, I need a separate count up and Count down signal, I don't think your circuit does that. And Moreever, By seing your explanation [""...and reset when both sensors are unblocked"" ]
I think that you are supposing that Sesor B should be covered before leaving Sensor A (i.e. the sensors should be placed near enough that a person cant fit in between the two (thereby leaving both sensor unblockde)
But in my actual circuit this may not be the case because my sensor produce signal on 'LEAVE' not on 'OBSTRUCT'.