pin one's hope on~

「Asahi Weekly」(Sunday,May,6,2012)から英語表現を拾います。
シャープが国内の液晶テレビでは最大サイズとなるなんと80型のアクオスを6月から発売すると発表しました。

Sharp pins hopes on 80-inch 'monster' LCD TV for consumers

OSAKA--Sharp Co. said April 18 it will market a liquid crystal display TV with a screen the size of a tatami mat in Japan from June.

The electronics giant said the 80-inch LCD TV, priced at 950,000 yen ($11,875), will be the biggest of its kind in Japan and sold under the Aquos brand.

Sharp said the screen, 1 meter high and 1.8 meters wide, is best viewed from 3 meters away.

The big TV will have Internet capability.

Sharp, which has sold an 80-inch LCD TV in the United States since last fall, expects sales in Japan to reach 12,000 units a year.

The Japanese LCD TV market has fallen off after a rush for digital due to the termination of analog broadcasts and the end of the government's Eco Point program for environmentally friendly appliances.

The number of units sold in fiscal 2012 that started this month is expected to fall by 7 million from fiscal 2011 to 10 million.

Sharp is pinning its hopes on the novelty of owning a huge TV to make up for the drop in sales.

"The key is whether people are attracted to the idea of a big screen and getting that message across," said Masanobu Tomatsuri, a senior official at Sharp, adding that Sharp expects demand to rise before the London Olympics get under way this summer.

Sharp operates the world’s only factory that can efficiently manufacture 60-inch or larger LCDs. The plant is located in Sakai, Osaka Prefecture. Last autumn, the company started selling a 70-inch Aquos TV, the largest available in the domestic market at that time.

Large-sized TVs are becoming increasingly popular in Japan. According to Sharp’s estimates, the market share of 50-inch or larger TVs almost tripled from 5.1 percent in June 2011 to 15.2 percent in December the same year in terms of sales amount.

pin downという表現をMinnesotaくんが取り上げていましたが（http://d.hatena.ne.jp/A30/20120503/1336047928）
pin one's hope on〜で、「〜に望みをかける」という意味(『ジーニアス英和辞典』、第4版)になります。She pinned her hopes on her son.(彼女は息子に望みをかけていた。)という例文が載っていました。
「〜に希望をピンで止める」=「〜に望みをかける」というイメージでしょうか。
pinにはもちろんの名詞pinは『ピン、留め具』などの意味がありますが、動詞の意味としては、「〜を押しつけて動かないようにする、を[約束・仕事に]縛り付ける、[希望・信頼など]を<人・物に>かけるという意味（『ジーニアス英和辞典』、第4版)もあります。
pinという単語にはなにかある種の必死さや抑制のニュアンスが含まれているのでこの記事で用いられたのではないでしょうか。(EnDough)