Keypad Scanner help!

So here is my second attempt. It works better, but the correct values are displayed on the LEDs only when I keep the key pressed down. When I release, the value displayed is the one on the third column again on the same row. Does anyone know where I am still going wrong? Also, are there too many processes here? Could I have designed this a better way? Thanks very much for any help as I am just in the learning phase still with VHDL.

ARCHITECTURE behaviour of KeypadScanner IS
SIGNAL pulse_10us : STD_LOGIC;
SIGNAL count : INTEGER := 0;
SIGNAL Key_write : STD_LOGIC_VECTOR (3 DOWNTO 0) := "0111";
BEGIN
Keypad_write<= Key_write;
----------------------------
PROCESS (clock_50)
BEGIN
If (clock_50'EVENT AND clock_50 = '1' ) THEN
	count<= count + 1;
	If (count = 500) THEN
		count<= 0;
	END IF;
END IF;
END PROCESS;
--------------------------------
PROCESS (clock_50)
BEGIN
If (clock_50'EVENT AND clock_50 = '1' ) THEN
	IF (count = 0) THEN
		pulse_10us<= '1';
	ELSIF (count = 1) THEN
		pulse_10us<= '0';
	END IF;
END IF;
	
END PROCESS;
-------------------------------------
PROCESS (clock_50)
BEGIN
If (clock_50'EVENT AND clock_50 = '1' ) THEN -- clock signal
     IF pulse_10us = '1' THEN -- enable signal
			If (Key_write = "0111") THEN
				Key_write<= "1011";
			ELSIF (Key_write = "1011") THEN
				Key_write<= "1101";
			ELSIF (Key_write = "1101") THEN
				Key_write<= "0111";
			END IF;
     END IF;
END IF;
END PROCESS;
--------------------------------------------
PROCESS (clock_50)
BEGIN
If (clock_50'EVENT AND clock_50 = '1' ) THEN -- clock signal
     IF pulse_10us = '1' THEN -- enable signal
			CASE Key_write IS
			 WHEN "0111" => 
				  If (Keypad_read = "0111" ) THEN
						LED<= "00000001";
				  ELSIf (Keypad_read = "1011") THEN
						LED<= "00000100";
				  ELSIf (Keypad_read = "1101") THEN
						LED<= "00000111";
				  END IF;
			 WHEN "1011" => 
				  If (Keypad_read = "0111" ) THEN
						LED<= "00000010";
				  ELSIf (Keypad_read = "1011") THEN
						LED<= "00000101";
				  ELSIf (Keypad_read = "1101") THEN
						LED<= "00001000";
				  END IF;
			WHEN "1101" => 
				  If (Keypad_read = "0111" ) THEN
						LED<= "00000011";
				  ELSIf (Keypad_read = "1011") THEN
						LED<= "00000110";
				  ELSIf (Keypad_read = "1101") THEN
						LED<= "00001001";
				  END IF;
        WHEN OTHERS => 
					LED<= "11111111";
		END CASE;
    END IF;
END IF;
END PROCESS;
------------------------------------------
END behaviour;