Apple (AAPL) probably knew that there would be some cannibalization when it released the iPad Mini, but few could have predicted it would lead to a 90% drop in interest for the full-size iPad.

According to Apple's official sales data, all versions of the iPad collectively sold 22.9 million units last quarter. The company did not break down the sales any further, leaving many to question the success of the iPad 4 versus the iPad Mini.

The answer might be found within a new report. According to DigiTimes, LG Display -- which manufactures displays for the iPad -- has reduced its full-size iPad display shipments by 90%.

In January 2012, LG Display shipped six million panels for the iPad. Last month the company shipped six-hundred thousand units.

This is obviously not the same as a sales decline, but it is significant and may point to a decline in interest for the 9.7-inch model.

DigiTimes' sources believe that the drop is "largely due to the growing popularity of the iPad Mini," as well as "increasing demand" for cheaper tablets.

Those tablets include the $169 Slate 7 from Hewlett-Packard (HPQ), along with similarly priced tablets from Google (GOOG), Barnes & Noble (BKS), Amazon (AMZN) and Samsung.

In addition to the rising threat of newer and cheaper competitors, iPad panel shipments may also be hurt by the slow winter production season. According to DigiTimes, January is typically a slow period for panel shipments.

But that seasonal flow changed last year when Apple decided to release the third-generation iPad in March 2012. Instead of waiting a full year to upgrade its tablet, Apple released the fourth-generation model last October. This could have altered the release of the next upgrade, which is now expected to come this summer (if not closer to fall). Consequently, Apple may not currently have the need for six million panels.

It will be interesting to see how the panel shipments compare when the fifth-generation model is about to be released.

Still, when looking at the total number of iPad panels currently being shipped, Apple may not be better off than it was last year.

LG Display is shipping as many as four million iPad Mini panels per month. When combined with the six-hundred thousand panels for the full-size model, that is a maximum of 4.6 million units for the month of January -- 1.4 million less than were shipped during the year ago period.

Shares of Apple are down more than 19% year-to-date. Amazon, one of the firm's emerging competitors, is up roughly one percent during the same period. Barnes & Noble has beaten the odds by gaining more than three percent. Google is up more than nine percent. Hewlett-Packard, a rising star on Wall Street, is up nearly 27%.

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