Around 300 workers are to lose their jobs at two Sony plants in south Wales, the company has announced.
The sales of flat-screen TVs in the UK are rising
The electronics firm announced on Thursday that 220 jobs would be lost at Pencoed and 80 at nearby Bridgend.
The company said the "changing market" for traditional cathode ray tube (CRT) televisions produced at the factories had resulted in the job losses.
Sony said customers had moved towards flat-screen televisions resulting in a lack of demand for the CRT models.
Sony makes cathode ray tubes at its Bridgend factory and the nearby Pencoed plant puts them into TV sets for the UK market. But the company said the accelerating trend to flat-screen televisions had hit demand for the products.
The company said that flat-screen TVs now accounted for half the market in value, with sales of the old-style larger screen TVs falling last year.
Sony said in a statement that this has had "a major impact" on demand for TVs made in south Wales and "we have to reassess the resources we need to deploy to meet market demand."
The statement continued: "We have reluctantly concluded that we will have to reduce the number of people we employ in south Wales to reflect the changing market environment."
Sony said it still expected demand for CRT products to be "significant in the medium term".
The company added that the Bridgend plant supplies cathode ray tubes to all Sony's European TV factories, including eastern Europe, where demand for the products is expected to remain.
But the company added that the Pencoed factory supplies TVs principally to the UK market, where there has been a "significant" growth in sales of flat panel models.
Sony will remain a major employer in the Bridgend area with 1,200 workers remaining at the two factories.
Union official with Amicus, Graham Smith, said: "This is devastating news for the workers and the impact of these job losses will be felt across south Wales.
The Sony factory at Pencoed produces televisions
"It comes as no surprise though as Hitachi, Panasonic and LG Phillips have shed hundreds of jobs in south Wales because of the demand for new technologies.
"We will be talking to Sony about the possibility of expanding the work on the professional broadcast camera and developing flat panel products to try and save jobs at their Pencoed plant."
Welsh Economic Development Minister, Andrew Davies, said help would be provided for the workers affected by the Sony job cuts.
He added: "I have set up a project team to assist the company and meetings have already taken place about the diversification of Sony.
"I am personally committed to doing all I can to help those facing redundancy and help the company remain a key employer in Wales."
Panasonic transferred TV and set-top box production from Cardiff to the Czech Republic in 2004.