TOKYO — A British branch of Pioneer Electronics Corp. will start production of set-top boxes in September that can be used for digital TV systems, and France’s Canal Plus is slated as one of the major customers for the products.Pioneer Electronics Technology (U.K.) Ltd. will make the boxes, which offer features such as Internet access and a variety of interactive services. The new manufacturing line is projected to produce about 500,000 boxes a year, a Pioneer spokesman in Tokyo said. Canal Plus is expected to buy about 200,000 of the boxes next spring. Pioneer did not disclose the value of the deal, but the spokesman did say Canal Plus will set the retail consumer price for the boxes. “We would like to continue our good business relations with Canal Plus,” the spokesman said. Pioneer is using its European set-top box production as a springboard for making boxes for the Japanese consumer market. The electronics firm wants to be the leader in Japan for interactive boxes when the consumer digital TV market expands significantly, the spokesman said. Earlier this year, Pioneer’s rival, Matsushita Electric Industry Co., closed a deal to produce set-top boxes with satcaster BSkyB and two other British firms. The partners agreed to form a new company, called British Interactive Broadcasting Ltd. (BIB). The other venture partners are Midland Bank and British Telecom. Matsushita will invest 15% of the total funding for the venture, with BSkyB and British Telecom holding 32.5% each, and Midland Bank holding the remaining 20%.