1. Field of the Invention
The present invention relates to a haptic input device used for, for example, car navigation systems etc. and, in particular, to an operability-improving means of an input device having a function of automatically attracting the cursor into an attractive point set on the menu-selection buttons displayed on display means in order to facilitate the selection of a desired button.
2. Description of the Related Art
Input devices are known in which display means displays menu-selection buttons and the cursor, and input means allows an operator to select a desired menu by moving the cursor to the displayed position of the desired button. In addition, some input means have a function that automatically attracts the cursor to an attractive point set on the button to facilitate the movement of the cursor to the displayed position of a desired button.
FIG. 8 is a block diagram of a known input device having an automatic cursor-attracting function. This input device includes an input means 101 which is operated by the operator and detects the amount of movement for itself; a display means 102 which displays a cursor moved by the input means 101 and input points (buttons), position-detecting means 103 which extracts the coordinates of the cursor displayed on the display means 102 from the amount of movement of the input means 101; and a driving means 104 which applies force to the input means 101 in accordance with the coordinates of the cursor. The input means 101 includes a rolling ball 105 which rolls on a desk, and a rotating angle-detecting means 106, 107 disposed in accordance with the x and y-axis of the display means 102 in order to detect the rotating amount of the rolling ball 105 in the x-axis direction and in the y-axis direction. The driving means 104 includes a driving unit 108 composed of motors 108a, 108b to drive the rolling ball 105 and a driving-signal generation unit 109 for generating driving signals of the driving unit 108 in accordance with signals from the position-detecting means 103 (refer to, for example, Japanese Examined Patent Application Publication No. 7-120247)
As shown in the lower part of FIG. 9, the driving signal generation unit 109 pre-stores the relationship among a relative distance between the cursor and the input point, a relative moving direction of the cursor towards the input point, and a driving signal supplied to the driving unit 108. As shown in the upper part of FIG. 9, when the cursor moves towards the input point by the operation of the input means 101 and the cursor enters the range of x1≦x≦x2, the driving signal “+1” shown in the lower part of FIG. 9 is supplied to the driving unit 108 by the driving-signal generation unit 109. Accordingly a driving force is applied to the rolling ball 105 so that such a sensation is provided to the input means 101 that the rolling ball 105 is attracted to the input point, as shown in the middle part of FIG. 9, and the cursor is attracted to the input point. In contrast, when the cursor moves away from the input point by the operation of the input means 101, and the cursor enters the range of x3≦x≦x4, the driving signal “−1” shown in the lower part of FIG. 9 is supplied to the driving unit 108 by the driving signal generation unit 109. Accordingly, a resistive force is applied to the rolling ball 105 so that such a sensation is provided to the input means 101 that the rotating ball 105 is pulled back to the input point.
Therefore, an input device of the above-described structure facilitates the operation with which the cursor moves to the desired input point. For example, this input device facilitates the menu selection displayed on the display means 102.
Meanwhile, as described in Patent Document 1, it is common that a plurality of menu selection buttons (input points) is disposed on the display means in various arrangements. However, the technology described in Patent Document 1 does not suppose the control of the attractive force when a plurality of buttons is displayed on the display means, in particular, when the buttons are closely located to one another. Therefore, if the technology described in Patent Document 1 is applied to an actual device, the input means may be influenced by the attractive force exerted toward the button that the cursor located before when the cursor moves from the displayed position of one button to that of the other, thus the operability of the input means becomes degraded, and the cursor cannot be smoothly moved to the desired button.
Specifically, as shown in the upper part of FIG. 10, if the configuration is such that first to third buttons B1, B2 and B3 are displayed in one line at regular intervals on the display means, and cursor-attractive areas A1, A2 and A3 are separately set up around each button B1, B2 and B3, a given attractive force is applied to the input means 101 in accordance with the distance from the attractive point (in the this case, the center positions O1, O2 and O3 of each button B1, B2 and B3) set in the attractive area where the cursor C enters to the current position of the cursor C when the cursor C is moved to one of the cursor-attractive areas A1, A2 and A3, and when the cursor C crosses the buttons B1, B2 and B3 one after another, the attractive force applied to the input means 101 is changed like the lower part of FIG. 10.
And, when the cursor moves from the attractive point O1 of the first button B1 to the attractive point O2 of the second button B2, an attractive force in accordance with the distance from the attractive point O1 to the current position of the cursor C is applied to the input means 101 while the cursor C moves from the attractive point O1 of the first button B1 to the borderline between the first attractive area A1 and the second attractive area A2, thus the operator exerts a large force on the input means 101 against this attractive force. And as soon as the cursor C crosses the borderline, the attractive force exerted toward the attractive point O1 is removed, and the attractive force in accordance with the distance from the attractive point O2 to the current position of the cursor C is applied to the input means 101. In this case, if the second button B2 is a button desired to select, the operator is required to weaken the force exerted on the input means 101. However, actually, the operator does not stop exerting the force against the attractive force exerted toward the attractive point O1, thus the cursor C can cross the borderline between the second attractive area and the third attractive area and enter the third attractive area A3.
That is, the operator continues to exert force in the moving direction of the cursor even after the attractive force exerted in the direction opposite to the moving direction of the cursor is removed, thus the cursor C can move to the outside of the attractive area of the desired button.
The present invention is devised to solve the afore-mentioned problem. Therefore the objective of the present invention is to provide a haptic input device in which the cursor does not move to the outside of the attractive area of the desired button when it moves among a plurality of buttons having an attractive area formed around each button.